AMR SERIES
Selected Case From the Arkadi M. Rywlin International Pathology Slide Series Mitochondrial Myopathy Presenting With Chronic Progressive External Ophthalmoplegia (CPEO): A Case Report Michele Bisceglia, MD,* Paola Crociani, MD,w Danilo Fogli, MD,w Antonio Centola, MD,z Carlos A. Galliani, MD,y and Gianandrea Pasquinelli, MD8
Abstract: A 43-year-old female patient diagnosed with chronic progressive external ophthalmoplegia (CPEO) because of mitochondrial myopathy documented by muscle biopsy is presented. The chief complaints were represented by blepharoptosis and ophthalmoplegia. The muscle biopsy was evaluated by histology, using the appropriate histochemical and histoenzimological stains. Ragged red fibers with Gomori trichrome stain were seen, which showed cytochrome c oxydase deficiency and abnormal succinate dehydrogenase staining in around 20% of muscle fibres. Electron microscopy was also performed which demonstrated abnormal, hyperplastic, pleomorphic, and hypertrophic mitochondria, characterized by paracrystalline inclusions arranged in parallel rows (“parking-lot” inclusions), consisting of rectangular arrays of mitochondrial membranes in a linear or grid-like pattern. In conclusion, mitochondrial myopathy was definitely diagnosed. Although molecular analysis, which was subsequently carried out, failed to reveal mutations in the mitochondrial DNA or in selected nuclear genes, the pathologic diagnosis was not changed. The differential diagnosis of CPEO with other forms of ocular myopathies as well as the possible association of CPEO with systemic syndromes is discussed. Ophtalmologists and medical internists should always suspect CPEO when dealing with patients affected by ocular myopathy, either in its pure form or in association with other myopathic or systemic signs. Key Words: mitochondria, myopathy, progressive external ophthalmoplegia, ragged-red fiber, intramitochondrial paracrystalline inclusions
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OVERVIEW Diagnosis: Chronic progressive external ophthalmoplegia. Referral source: AMR seminar #61 (case number 5).
CLINICAL HISTORY A 43-year-old female patient presented with a 3-year history of progressive bilateral blepharoptosis, followed by From the *IRCCS, Referral Cancer Center of Basilicata, Rionero in Vulture (PZ); wNeurology Unit, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo (FG); zOphthalmology Unit, “F. Lastaria” Hospital, Lucera, Italy; 8Department of Clinical Pathology, S. Orsola Polyclinic, University of Bologna, Bologna, Italy; and yDepartment of Pathology, Children’s Hospitals and Clinics of Minnesota, Minneapolis, MN. The authors have no NIH funding or conflicts of interest to disclose. Reprints: Michele Bisceglia, MD, Via Santa Chiara 9, Manfredonia (FG) 71043, Italy (e-mail: [email protected]). All figures can be viewed online in color at http://www. anatomicpathology.com. Copyright r 2014 by Lippincott Williams & Wilkins
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arthralgias, mild proximal muscular weakness, and occasional episodes of dysphonia, in the absence of dysphagia, muscle cramps, and myoglobinuria. On the basis of moderately elevated serum levels of creatine phosphokinase (325 to 735 units/L; reference < 170), lactate dehydrogenase (546 to 1820 units/L; reference < 460), and electromyographic disturbances, a diagnosis of polymyositis was made at another institution 2 years earlier, for which she was given corticosteroids. Her serum enzymes normalized after 1 year, so her corticosteroid therapy was discontinued. However, her clinical symptoms persisted. Blepharoptosis was her chief manifestation, to the point that the patient occasionally lifted her eyelids manually. On admission, neurologic examination documented myopathic facies with bilateral nonfluctuant blepharoptosis, ophthalmoplegia with inability to look downward, reactive contraction of the frontal muscle (to help elevate the lids), and bilateral atrophy of both temporalis muscles. The orbicularis oculi muscles were bilaterally normal. Diplopia was not a complaint. Physical examination of the patient also revealed mild weakness of the neck, left pectoralis, and right medium gluteus muscles, in association with slight scoliosis and bilateral winged scapula. Her gate was unaffected, but changing from a sitting to a supine position was impaired. Osteotendinous reflexes were diminished. The patient was nulliparous and nulligravida, nonobese and nondiabetic, and born to healthy nonconsanguinous parents, both originating from the same small town, whose family history included 2 relatives (1 niece and 1 father’s cousin) diagnosed with muscular dystrophy-NOS.
Laboratory and Clinical Investigations CPK, LDH, free T3, free T4, and TSH were within normal range. Anti-acetylcholine receptor and anti-muscle specific tyrosine kinase receptor protein antibodies were nondetectable, thus excluding myasthenia gravis. Liver enzymes were normal. Serology for rheumatoid arthritis and systemic lupus erythematosus as well as for HBsAg and HCV was negative. Chest x-ray was normal; electrocardiogram and electroencephalogram were normal. Ultrasonographic examination of the aortic arch branches was normal. Magnetic resonance imaging of the brain and orbits was normal. Ear, nose, and throat examination including audiometry and vestibulometric tests were normal. Ophthalmologic examination, including fundoscopic www.anatomicpathology.com |
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evaluation for pigmentary retinopathy, was normal except for blepharoptosis and ophthalmoplegia.
SKELETAL MUSCLE BIOPSY With the clinical suspicion of mitochondrial myopathy the patient underwent open biopsy of the deltoid muscle.
Tissue Preparation The skeletal muscle specimen was divided. A main portion of the muscle tissue was appropriately oriented (longitudinally and transversely) and mounted on thin cork discs, using Tissue-Tek as adhesive, and snap-frozen in isopentane, cooled in a metal container suspended in the mouth of a vacuum flask half-filled with liquid nitrogen. The cork disc with the mounted fragment of muscle was then placed on a metal chuck, snap-frozen, and serially sectioned in a cryostat at 201C. A duplicate series of twenty 5-mm-thick transverse tissue sections were obtained for histochemical and histoenzymatic staining. Smaller portions of muscle tissue were snap frozen and others immersed in gluteraldehyde for molecular and ultrastructural analysis, respectively.
Histochemical and Histoenzymatic Stains— Methods and Indications The following histochemical stains were performed: haematoxylin and eosin, modified Gomori trichrome (mitochondria stain red), Verhoeff van Gieson (fibrous tissue), PAS and PAS with diastase digestion for glycogen, oil-red-O and Sudan-black for neutral lipids. The following histoenzymatic stains were performed: myosin adenosine triphosphatase for myofibrils (myosin ATPase), with preincubation at pH 10.0, pH 4.5, and pH 4.28; myophosphorylase, phosphofructokinase, and myoadenylate deaminase for the cytosol intermyofibrillary enzymatic reactivity; and nicotine adenine dinucleotide dehydrogenase tetrazolium reductase, cytochrome c oxydase (COX), and succinate dehydrogenase (SDH) for mitochondrial activity of the muscle fibers. COX and SDH stainings were performed according to a double-staining method. Nonspecific esterase for any possible denervated fiber and acid phosphatase for any autophagic intrafibrillary vacuoles were also performed. COX reflects the activity of complex IV of the mitochondrial respiratory chain and is mainly encoded by mitochondrial DNA (mtDNA), and COX-deficient fibres are considered to be indicative of mitochondrial disorders. SDH evaluates the activity of complex II of the mitochondrial respiratory chain and is encoded exclusively by nuclear DNA (nDNA). Thus, a useful sequential double staining has been devised, the COX-SDH stain, to better assess the muscle fiber mitochondrial content and activity. Normal, positive reacting COX fibers stain light brown, whereas normal SDH fibers are blue. COX deficient fibers fail to stain and appear as gaps in the tissue, which sometimes can be difficult to separate from actually missing fibers. Muscle affected by mitochondriopathies stain with SDH more darkly than normal, reflecting mitochondrial hyperplasia and hypertrophy, consistently associated with and maybe reactive to the COX deficiency. The double COX-SDH staining method stains all the normally reactive fibers grey-brown (a balanced color imparted by the 2 single colors from both methods).
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Note Regarding the Glass Slides Circulated in the Club Each AMR member received only 1 slide which was labeled either “A,” corresponding to Gomori stain, assessing raw mitochondrial content, or “B” corresponding to COX-SDH stain, assessing both complex IV and complex II activities. The results of both these main stains for mitochondrial myopathies were photographed and appended in the AMR Web site and could be viewed at http://www.amr-seminar.org/seminar/61/images.php.
Histopathologic Features On haematoxylin and eosin, the muscle exhibited a normal architecture. The myocytes were mostly uniform in size, had polygonal contours, and normally placed peripheral nuclei. However, on this apparent normal background a few scattered abnormally stained myocytes with irregular cell contours could also be seen (Fig. 1A). No necrotic fibers or inflammatory infiltrates were seen. Verhoeff van Gieson stain showed physiologic amounts of interstitial collagen, and PAS with and without diastase digestion showed no significant increased glycogen content. Gomori trichrome highlighted patchily distributed ragged-red fibers (10% of the total), that is, fibers with irregular subsarcolemmal rims of reddish material, indicating subsarcolemmal accumulation of mitochondria (Figs. 1B–F). The sequential COX-SDH stained sections showed scattered hyper-reactive dark-blue fibers (20% of the total), corresponding to those fibers with mitochondrial hyperplasia and COX activity deficiency, on a background of grey-brown fibers (Fig. 2). Nicotine adenine dinucleotide dehydrogenase tetrazolium reductase stain, which evaluates the activity of complex I (encoded by both nuclear and mitochondrial DNA), revealed some hyper-reactive dark fibers (10% of the total). Myosin ATPase reactions showed normal type I and type II fibers, predominately slow-twitch type I fibers, in accordance with the biopsy site (deltoid muscle). The rest of the enzymatic stains highlighted a normal activity of the intermyofibrillary network. Oil-red-O and Sudan black stains revealed slight increased neutral lipid droplets in the myocytes.
Ultrastructural Features The salient finding was supernumerary subsarcolemmal and intermyofibrillar collections of mitochondria. These organelles were unduly large and pleomorphic and often contained paracrystalline inclusions between the inner and outer membranes of the mitochondrial walls, replacing the cristae. These paracrystalline inclusions were frequently multiple and arranged in parallel rows (parking-lot inclusions) and consisted of rectangular arrays of mitochondrial membranes in a linear or grid-like pattern. Occasionally the mitochondrial membranes were arranged in whorls. A few intramitochondrial osmiophilic dense bodies in the matrix were also seen (Figs. 3, 4). Other pathologic findings were focal and moderate lysis of the sarcolemmal myofibrils as well as focal and moderate increase of the cytoplasmic lipid and glycogen content.
Clinicopathologic Diagnosis On the basis of clinical, histologic, histoenzymatic, and ultrastructural findings the diagnosis of mitochondrial myopathy presenting with chronic progressive external ophthalmoplegia (CPEO) in association with moderate proximal myopathy was made. r
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Progressive External Ophthalmoplegia
FIGURE 1. Deltoid muscle, cross section. (A, hematoxylin and eosin; B–F, Gomori trichrome stain). (A) Well-preserved striated muscle architecture. Three myocytes with irregular structure and/or abnormal staining (arrows) among the normal ones. (B–F) Patchy distribution of ragged-red fibers. Subsarcolemmal rims of bright red or red-blue material, which correspond to accumulated hypertrophic and hyperplastic mitochondria: Inset in (F): ragged-red fiber at higher magnification.
AUTHOR’S COMMENT Mitochondria are the main source of energy production in mammalian cells and accordingly primary mitochondrial disorders, affecting the respiratory chain’s ability to undergo oxidative phosphorylation and leading to r
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decreased production of ATP, clinically involve tissues with the highest energy requirements, such as the nervous, muscular, cardiac, and endocrine systems. Mitochondrial myopathies (MM) are mitochondrial disorders, caused by mutations in both the nuclear and www.anatomicpathology.com |
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FIGURE 2. (A–F) COX-SDH double-staining method. Cross-section of striated muscle with many grey-blue affected myocytes, showing a mosaic pattern as seen in patients with mtDNA disorders. These grey-blue fibers are COX negative and correspond to the ragged-red fibers seen in Figure 1. The grey-blue staining tinctorial appearance is because of preserved enzymatic reactivity of supernumerary mitochondria for SDH. COX-SDH indicates cytochrome c oxydase-succinate dehydrogenase.
mitochondrial genomes, featuring myopathy, which may occur at any age with a prevalence of approximately 1 in 10,000 people.1 Involvement of the external ocular muscles (ocular myopathy), including levator palpebrae and extrinsic eye
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muscles, and manifesting as symmetric, bilateral palpebral ptosis and ophthalmoparesis, is a main feature of various MM, and is the dominant symptom in CPEO, a condition, also known as progressive external ophthalmoplegia (PEO), which may present from childhood up to late adulthood.2 r
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FIGURE 3. Ragged-red fiber. Electron microscopical analysis. (A) Moderate lysis of contractile elements and an osmiophilic dense body ( 3000). (B) The sarcoplasm contains pleomorphic mitochondria, some smaller than normal (arrowheads) and others large and emptyappearing with degraded cristae ( 6000). (C) Subsarcolemmal accumulation of mitochondria with scattered, rectangular electron dense material (arrows) and a few large lipid droplets (asterisks). ( 6000) (D) The dense material in the mitochondrial matrix are paracrystalline inclusions ( 18,000).
PEO is a relatively mild form of MM, characterized by blepharoptosis and ophthalmoplegia, almost always in the absence of diplopia, pain, proptosis, and pupil involvement, which may clinically manifest in a pure form or in association with proximal myopathy.2–4 In either case PEO is always a systemic disease as is attested to by the presence of mitochondrial abnormalities seen in biopsies, taken from muscle other than the extrinsic eye muscle (usually the deltoid or quadriceps muscle). In our patient the MM involved exclusively the muscular system and manifested with PEO, as the most important symptom, in association with moderate proximal myopathy. r
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PEO can either be maternally inherited, both from asymptomatic or clinically affected mothers, or arise de novo in the proband. Other symptoms deriving from the multisystem mitochondrial involvement may be either absent in PEO or variably present to a mild degree. PEO can also be part of other more complex mitochondrial syndromes with severe multi-organ dysfunction, such as Kearns-Sayre syndrome (occurring in the young mainly in association with pigmentary retinopathy, cardiac conduction disorders, and diabetes mellitus), sensory ataxic neuropathy, dysarthria, and ophtalmoparesis, various forms of ataxia neuropathy syndromes, and mitochondrial www.anatomicpathology.com |
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FIGURE 4. Ragged-red fiber. Electron microscopical analysis. (A–C) Intramitochondrial crystal-like inclusions arranged in parallel rows within the intermembrane compartment (“parking lot” inclusions). The mitochondria containing paracrystalline inclusions are devoid of cristae. The myofibrillar architecture in (A) is still relatively preserved, whereas in (B and C) is severely altered with disarray and fragmentation of myofibrils. Prominent lipid droplets are also seen in (A and B). In the right lower corner of (C) is a cell membrane (sarcolemma) of a myocyte with a small portion of the endomysium. [magnifications: A, ( 9000); B, ( 12,000); C, ( 23,000)] Inset in (B): paracrystalline inclusion with arrays of mitochondrial cristal membranes in a linear pattern. Inset in (C): higher magnification of the crystal-like inclusions indicated with arrow, showing rectangular arrays of mitochondrial membranes arranged in a grid-like pattern (original magnification 12,000, and 18,000, respectively) (D) Subsarcolemmal accumulation of mitochondria with thin curvilinear arrays of paracrystalline membranes, visible in the outer compartment space between the inner and outer mitochondrial membrane. The cell membrane, endomysium, and an adjacent portion of an apparently preserved muscle fiber are seen at the upper left part of the picture ( 18,000). Inset in (D): mitochondrial cristae arranged in a whorl of parallel membranes (original magnification 18,000).
neurogastrointestinal encephalopathy, which are all diagnosed on skeletal muscle biopsy.2 Incidentally, mitochondrial neurogastrointestinal encephalopathy can also be diagnosed or suspected with gastrointestinal biopsy, as characteristic megamitochondria have been reported in gastrointestinal ganglion and smooth muscle cells.5
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Mitochondrial disorders occasionally manifest as polyneuropathy either as the dominant feature or as one of many other manifestations (inherited mitochondrial neuropathy).6 Mitochondrial disorders, in which polyneuropathy is the dominant feature, include a syndromic form (socalled NARP, neuropathy, ataxia, retinitis r
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pigmentosa) and a few other inherited mitochondrial neuropathies, one of which manifests in association with PEO (mixed axonal and demyelinating sensori-motor neuropathy with PEO).6 However, some MM (around a third of the total) do not typically present with ocular myopathy, such as myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS) and myoclonus, epilepsy, and ragged-red fibers (MERFF), the 2 best known clinically systemic MM, which may also be associated with additional symptoms (ie, ataxia and cardiomyopathy in both, and deafness and endocrinopathy in the former).2 Other MM not associated with ocular myopathy are some forms of ataxia neuropathy syndromes, some forms of isolated MM, and some forms of infantile MM.2 MM have diverse genetic etiologies with a poor genotype-phenotype correlation, with the same mutation presenting highly variable phenotypes both within and between families (this is because of heteroplasmy). MM also exhibits a highly variable pattern of inheritance. Molecular analysis of mtDNA may either show point mutations and single large-scale deletions or depletions and multiple deletions, the latter as secondary effects of mutations involving nuclear genes encoding subunits of the mitochondrial respiratory chain, structural mitochondrial proteins, proteins for mitochondrial maintance, and/or proteins for intergenomic communication.2,7–13 Regarding the clinical approach to ocular myopathy there are a few considerations to be taken into account: (1) ocular myopathy, mainly palpebral ptosis can be of various origins14; (2) all patients with ocular myopathy should be suspected to harbour MM; (3) in some of these patients myopathy can be overshadowed by other clinical manifestations; (4) ocular myopathy in MM is of long-standing duration (this excludes some forms of eye muscle paresis of acute onset, such as botulism); (5) all patients with suspected MM should undergo cardiac, endocrine, auditory, and visual investigations; (6) some patients who present with mitochondrial symptoms, including ocular myopathy, may not have a primary mitochondrial disease (as occurs with exposure to toxins, including some medications that affect mitochondrial function).7 Extrinsic eye muscles have fundamentally distinct properties that make them selectively vulnerable to certain neuromuscular disorders.15,16 These muscles contain a much greater volume of mitochondria than any other muscle group, and this results in their preferential clinical involvement in MM, which occurs in around two thirds of affected patients. The clinical differential diagnosis of PEO includes several diseases, such as myastenic syndromes, ocular myositis, thyroid associated orbitopathy, and a few primary dystrophic myopathies, such as oculopharyngeal muscular dystrophy16–18 and myotonic dystrophy,16,18,19 and occasionally also facioscapulohumeral dystrophy16 and limb girdle muscular dystrophy.20 Myasthenia gravis is the main differential diagnostic consideration of all: in fact, although this disease has specific clinical distinguishing features (eg, fluctuant ophthalmoplegia, asymmetrical palpebral ptosis, diplopia, and weakness of the orbicularis oculi muscles) and its diagnosis is confirmed by the presence of anti-acetylcholine receptor and/or anti-muscle specific tyrosine kinase receptor antibodies, patients presenting with atypical forms of PEO may still be misdiagnosed with myasthenia gravis21–24 and r
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undergo unnecessary thymectomy.22 Eye muscle involvement is uncommon but may also occur in Lambert-Eaton syndrome, which is another myasthenic disorder, often of paraneoplastic origin (small cell carcinoma of lung), to be considered in adults, which is caused by antibodies directed to the voltage-gated calcium channels at the neuromuscular junctions. Muscle biopsy is the main diagnostic tool to correctly diagnose MM, including PEO. Of note, 2 relatives in our patient’s family, who were likely affected by MM and did not undergo muscle biopsy, had previously been clinically diagnosed with muscular dystrophy-NOS. The major diagnostic features of mitochondrial myopathy are: (I) the presence of a substantial number of COXnegative fibers (> 5% of the total muscle fibers) as seen by histoenzymatic analysis and/or by the equivalent raggedred fibers as seen with Gomori stain, and (II) the ultrastructural detection of hyperplastic and abnormal mitochondria with characteristic paracrystalline inclusions. Histologically, there are 2 main patterns of morphologic changes suggesting to the pathologist whether the molecular etiology is a primary defect of mtDNA or a primary defect of nDNA: as a general rule, when COX-deficient fibers are scattered in a mosaic-pattern, mtDNA mutation is suggested, whereas when COX is uniformly decreased in muscle fibers a nDNA mutation is likely. However, the pathologist should be aware of the rare occurrence in which the biochemical defect of MM does not involve complex IV/COX, and in these cases the histoenzymatic analysis is normal. Electron microscopy is fundamental, both as a confirmatory and a complementary diagnostic tool in these diseases. Medical treatment is limited, including administration of vitamins and cofactors, but newer therapies are being investigated.2,9,11,25,26 Plastic surgery aiming to correct palpebral ptosis can be suggested in the most severe forms, although postoperative complications (mainly corneal exposure and ulceration) have also been recorded.18,24,27,28
Follow-up In this case the molecular analysis of mtDNA, which was performed for MERFF, MELAS, NARP, and KearnsSayre syndromes, and the direct sequencing of tRNAleuc and tRNAlys nuclear genes did not disclose any mutation. Because a negative molecular analysis does not exclude MM, our diagnosis remains unchanged. The patient was given supplementation therapy with Lcarnitine29,30 and coenzyme Q10.31 At present, 8 years after diagnosis, the disease is stable. Now, we cannot exclude the possibility that her MM was due to primary Co Q10 deficiency.
CLUB’S OPINIONS Beautiful case, thanks for giving us the opportunity to see this rare type of myopathy. The stain is fascinating. Mitochondrial myopathy associated with progressive external ophthalmoplegia. Thanks for the encyclopaedic discussion. Thanks for the case with such incredible discussion. I have the Gomori stained slide (marked A underneath the label) and seen many small red specks which remind me of AFB seen with Z-N. Can neither agree nor disagree with the diagnosis since it will be a cold day in hell when I am able to interpret www.anatomicpathology.com |
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frozen sections of muscle. This appears to be a beautiful discussion although I must admit I am not confident enough to understand half of it. “Ragged-red fibers” and “parking lot bodies” takes me many years back. Lovely stain! Our specialist for EM & muscle biopsies agrees that on the basis of the case history, HC and EM this is a classical example of mitochondrial myopathy with PEO. Wow! How very interesting! No wonder the neurologists keep that area for themselves at our hospital. Mitochondrial myopathy presenting with progressive external ophthalmoplegia (PEO). This is a typical case of neuromuscular disease of which I have just elementary education. This area of pathology is currently managed by neurologists. Still I appreciated very much receiving your slide and seeing in AMR website the pictures of both stains (Gomori stain as well as COX-SDH stain), which clearly shows the enzymatic mitochondrial defect, underlying this type of primary myopathy. Mitochondrial myopathy, very informative account— thank you. Typical case of mitochondrial myopathy. Thank you for such a good documented case. I appreciate your endless (and fruitless, sadly to say) efforts to educate people like me. Is there any field of pathology you have no expertise on? Highly educational case. Great discussion. Thank you very much. Interesting case of mitocondrial myopathy, and nice discussion, thank you. No comments, extraordinary documentation. Thank you for this treatise on mitochondrial myopathies. I have no experience with muscle biopsy interpretation. This brings back memories of muscle biopsy days and looking at the ultrastructure of these cases of mitochondrial myopathy. It must be at least 20 years since I have seen a muscle biopsy now. Thanks for the encyclopaedic review. It was clear in reading your dissertation that this field has well and truly passed me by! REFERENCES
1. Schaefer AM, McFarland R, Blakely EL, et al. Prevalence of mitochondrial DNA disease in adults. Ann Neurol. 2008;63: 35–39. 2. Pfeffer G, Chinnery PF. Diagnosis and treatment of mitochondrial myopathies. Ann Med. 2013;45:4–16. 3. Serratrice G, Pellissier JF. [Ocular myopathies. Nosological study of 49 cases]. Presse Med. 1987;16:1969–1974. 4. Serratrice G, Pellissier JF, Desnuelle C, et al. Mitochondrial and ocular myopathies (62 cases). Rev Neurol (Paris). 1991;147:474–475. 5. Perez-Atayde AR. Diagnosis of mitochondrial neurogastrointestinal encephalopathy disease in gastrointestinal biopsies. Hum Pathol. 2013;44:1440–1446. 6. Finsterer J. Inherited mitochondrial neuropathies. J Neurol Sci. 2011;304:9–16. 7. Cohen BH. Neuromuscular and systemic presentations in adults: diagnoses beyond MERRF and MELAS. Neurotherapeutics. 2013;10:227–242.
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8. DiMauro S, Hirano M. Mitochondrial encephalomyopathies: an update. Neuromuscul Disord. 2005;15:276–286. 9. DiMauro S. Pathogenesis and treatment of mitochondrial myopathies: recent advances. Acta Myol. 2010;29:333–338. 10. DiMauro S. Mitochondrial encephalomyopathies—fifty years on: the Robert Wartenberg Lecture. Neurology. 2013;81: 281–291. 11. DiMauro S, Schon EA, Carelli V, et al. The clinical maze of mitochondrial neurology. Nat Rev Neurol. 2013;9:429–444. 12. Goldstein AC, Bhatia P, Vento JM. Mitochondrial disease in childhood: nuclear encoded. Neurotherapeutics. 2013;10: 212–226. 13. Servidei S. Mitochondrial encephalomyopathies: gene mutation. Neuromuscul Disord. 2004;14:107–116. 14. Clauser L, Tieghi R, Galie` M. Palpebral ptosis: clinical classification, differential diagnosis, and surgical guidelines: an overview. J Craniofac Surg. 2006;17:246–254. 15. Farrugia ME. Myasthenic syndromes. J R Coll Physicians Edinb. 2011;41:43–47. 16. Pe´nisson-Besnier I, Lamirel C. Ocular disturbances in neuromuscular disorders. Rev Neurol (Paris). 2008;164:902–911. 17. Gautier D, Pe´nisson-Besnier I, Rivaud-Pe´choux S, et al. Ocular motor deficits in oculopharyngeal muscular dystrophy. Eur J Neurol. 2012;19:e38. 18. Doherty M, Winterton R, Griffiths PG. Eyelid surgery in ocular myopathies. Orbit. 2013;32:12–15. 19. Thiriez C, Vignal C, Papeix C, et al. Ophthalmoplegia as the presenting muscle-related manifestation of myotonic dystrophy. Rev Neurol (Paris). 2010;166:538–541. 20. Filosto M, Tonin P, Vattemi G, et al. Chronic ophthalmoparesis in limb girdle muscular dystrophy 1C. J Neurol Neurosurg Psychiatry. 2009;80:448–449. 21. Barton JJ, Maguire J, Mezei M, et al. Mitochondrial pseudomyasthenia. J Neuro Ophthalmol. 2010;30:248–251. 22. Ben Yaou R, Laforeˆt P, Be´cane HM, et al. Misdiagnosis of mitochondrial myopathies: a study of 12 thymectomized patients. Rev Neurol (Paris). 2006;162:339–346. 23. Owens WE, Gupta D, Bertorini T. Enhancement of contralateral ptosis on passively holding an eyelid in mitochondrial myopathy resembling myasthenia gravis. J Clin Neuromuscul Dis. 2005;6:188–190. 24. Schoser BG, Pongratz D. Extraocular mitochondrial myopathies and their differential diagnoses. Strabismus. 2006;14: 107–113. 25. Lee AG, Brazis PW. Chronic progressive external ophthalmoplegia. Curr Neurol Neurosci Rep. 2002;2:413–417. 26. Scarpelli M, Cotelli MS, Mancuso M, et al. Current options in the treatment of mitochondrial diseases. Recent Pat CNS Drug Discov. 2010;5:203–210. 27. Lucci LM, Fonseca Junior NL, Sugano DM, et al. Tarsal switch levator for mitochondrial myogenic ptosis. Arq Bras Oftalmol. 2009;72:159–163. 28. Soejima K, Sakurai H, Nozaki M, et al. Surgical treatment of blepharoptosis caused by chronic progressive external ophthalmoplegia. Ann Plast Surg. 2006;56:439–442. 29. Gimenes AC, Napolis LM, Silva NL, et al. The effect of Lcarnitine supplementation on respiratory muscle strength and exercise tolerance in patients with mitochondrial myopathies. [Abstract]. Eur Respir J. 2007;51(suppl):21S[E297]. 30. Gallagher CL, Waclawik AJ, Beinlich BR, et al. Friedreich’s ataxia associated with mitochondrial myopathy: clinicopathologic report. J Child Neurol. 2002;17:453–456. 31. Montini G, Malaventura C, Salviati L. Early coenzyme Q10 supplementation in primary coenzyme Q10 defi ciency. N Engl J Med. 2008;358:2849–2850.
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Selected Case From the Arkadi M. Rywlin International Pathology Slide Series Mitochondrial Myopathy Presenting With Chronic Progressive External Ophthalmoplegia (CPEO): A Case Report Michele Bisceglia, MD,* Paola Crociani, MD,w Danilo Fogli, MD,w Antonio Centola, MD,z Carlos A. Galliani, MD,y and Gianandrea Pasquinelli, MD8
Abstract: A 43-year-old female patient diagnosed with chronic progressive external ophthalmoplegia (CPEO) because of mitochondrial myopathy documented by muscle biopsy is presented. The chief complaints were represented by blepharoptosis and ophthalmoplegia. The muscle biopsy was evaluated by histology, using the appropriate histochemical and histoenzimological stains. Ragged red fibers with Gomori trichrome stain were seen, which showed cytochrome c oxydase deficiency and abnormal succinate dehydrogenase staining in around 20% of muscle fibres. Electron microscopy was also performed which demonstrated abnormal, hyperplastic, pleomorphic, and hypertrophic mitochondria, characterized by paracrystalline inclusions arranged in parallel rows (“parking-lot” inclusions), consisting of rectangular arrays of mitochondrial membranes in a linear or grid-like pattern. In conclusion, mitochondrial myopathy was definitely diagnosed. Although molecular analysis, which was subsequently carried out, failed to reveal mutations in the mitochondrial DNA or in selected nuclear genes, the pathologic diagnosis was not changed. The differential diagnosis of CPEO with other forms of ocular myopathies as well as the possible association of CPEO with systemic syndromes is discussed. Ophtalmologists and medical internists should always suspect CPEO when dealing with patients affected by ocular myopathy, either in its pure form or in association with other myopathic or systemic signs. Key Words: mitochondria, myopathy, progressive external ophthalmoplegia, ragged-red fiber, intramitochondrial paracrystalline inclusions
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OVERVIEW Diagnosis: Chronic progressive external ophthalmoplegia. Referral source: AMR seminar #61 (case number 5).
CLINICAL HISTORY A 43-year-old female patient presented with a 3-year history of progressive bilateral blepharoptosis, followed by From the *IRCCS, Referral Cancer Center of Basilicata, Rionero in Vulture (PZ); wNeurology Unit, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo (FG); zOphthalmology Unit, “F. Lastaria” Hospital, Lucera, Italy; 8Department of Clinical Pathology, S. Orsola Polyclinic, University of Bologna, Bologna, Italy; and yDepartment of Pathology, Children’s Hospitals and Clinics of Minnesota, Minneapolis, MN. The authors have no NIH funding or conflicts of interest to disclose. Reprints: Michele Bisceglia, MD, Via Santa Chiara 9, Manfredonia (FG) 71043, Italy (e-mail: [email protected]). All figures can be viewed online in color at http://www. anatomicpathology.com. Copyright r 2014 by Lippincott Williams & Wilkins
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arthralgias, mild proximal muscular weakness, and occasional episodes of dysphonia, in the absence of dysphagia, muscle cramps, and myoglobinuria. On the basis of moderately elevated serum levels of creatine phosphokinase (325 to 735 units/L; reference < 170), lactate dehydrogenase (546 to 1820 units/L; reference < 460), and electromyographic disturbances, a diagnosis of polymyositis was made at another institution 2 years earlier, for which she was given corticosteroids. Her serum enzymes normalized after 1 year, so her corticosteroid therapy was discontinued. However, her clinical symptoms persisted. Blepharoptosis was her chief manifestation, to the point that the patient occasionally lifted her eyelids manually. On admission, neurologic examination documented myopathic facies with bilateral nonfluctuant blepharoptosis, ophthalmoplegia with inability to look downward, reactive contraction of the frontal muscle (to help elevate the lids), and bilateral atrophy of both temporalis muscles. The orbicularis oculi muscles were bilaterally normal. Diplopia was not a complaint. Physical examination of the patient also revealed mild weakness of the neck, left pectoralis, and right medium gluteus muscles, in association with slight scoliosis and bilateral winged scapula. Her gate was unaffected, but changing from a sitting to a supine position was impaired. Osteotendinous reflexes were diminished. The patient was nulliparous and nulligravida, nonobese and nondiabetic, and born to healthy nonconsanguinous parents, both originating from the same small town, whose family history included 2 relatives (1 niece and 1 father’s cousin) diagnosed with muscular dystrophy-NOS.
Laboratory and Clinical Investigations CPK, LDH, free T3, free T4, and TSH were within normal range. Anti-acetylcholine receptor and anti-muscle specific tyrosine kinase receptor protein antibodies were nondetectable, thus excluding myasthenia gravis. Liver enzymes were normal. Serology for rheumatoid arthritis and systemic lupus erythematosus as well as for HBsAg and HCV was negative. Chest x-ray was normal; electrocardiogram and electroencephalogram were normal. Ultrasonographic examination of the aortic arch branches was normal. Magnetic resonance imaging of the brain and orbits was normal. Ear, nose, and throat examination including audiometry and vestibulometric tests were normal. Ophthalmologic examination, including fundoscopic www.anatomicpathology.com |
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evaluation for pigmentary retinopathy, was normal except for blepharoptosis and ophthalmoplegia.
SKELETAL MUSCLE BIOPSY With the clinical suspicion of mitochondrial myopathy the patient underwent open biopsy of the deltoid muscle.
Tissue Preparation The skeletal muscle specimen was divided. A main portion of the muscle tissue was appropriately oriented (longitudinally and transversely) and mounted on thin cork discs, using Tissue-Tek as adhesive, and snap-frozen in isopentane, cooled in a metal container suspended in the mouth of a vacuum flask half-filled with liquid nitrogen. The cork disc with the mounted fragment of muscle was then placed on a metal chuck, snap-frozen, and serially sectioned in a cryostat at 201C. A duplicate series of twenty 5-mm-thick transverse tissue sections were obtained for histochemical and histoenzymatic staining. Smaller portions of muscle tissue were snap frozen and others immersed in gluteraldehyde for molecular and ultrastructural analysis, respectively.
Histochemical and Histoenzymatic Stains— Methods and Indications The following histochemical stains were performed: haematoxylin and eosin, modified Gomori trichrome (mitochondria stain red), Verhoeff van Gieson (fibrous tissue), PAS and PAS with diastase digestion for glycogen, oil-red-O and Sudan-black for neutral lipids. The following histoenzymatic stains were performed: myosin adenosine triphosphatase for myofibrils (myosin ATPase), with preincubation at pH 10.0, pH 4.5, and pH 4.28; myophosphorylase, phosphofructokinase, and myoadenylate deaminase for the cytosol intermyofibrillary enzymatic reactivity; and nicotine adenine dinucleotide dehydrogenase tetrazolium reductase, cytochrome c oxydase (COX), and succinate dehydrogenase (SDH) for mitochondrial activity of the muscle fibers. COX and SDH stainings were performed according to a double-staining method. Nonspecific esterase for any possible denervated fiber and acid phosphatase for any autophagic intrafibrillary vacuoles were also performed. COX reflects the activity of complex IV of the mitochondrial respiratory chain and is mainly encoded by mitochondrial DNA (mtDNA), and COX-deficient fibres are considered to be indicative of mitochondrial disorders. SDH evaluates the activity of complex II of the mitochondrial respiratory chain and is encoded exclusively by nuclear DNA (nDNA). Thus, a useful sequential double staining has been devised, the COX-SDH stain, to better assess the muscle fiber mitochondrial content and activity. Normal, positive reacting COX fibers stain light brown, whereas normal SDH fibers are blue. COX deficient fibers fail to stain and appear as gaps in the tissue, which sometimes can be difficult to separate from actually missing fibers. Muscle affected by mitochondriopathies stain with SDH more darkly than normal, reflecting mitochondrial hyperplasia and hypertrophy, consistently associated with and maybe reactive to the COX deficiency. The double COX-SDH staining method stains all the normally reactive fibers grey-brown (a balanced color imparted by the 2 single colors from both methods).
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Note Regarding the Glass Slides Circulated in the Club Each AMR member received only 1 slide which was labeled either “A,” corresponding to Gomori stain, assessing raw mitochondrial content, or “B” corresponding to COX-SDH stain, assessing both complex IV and complex II activities. The results of both these main stains for mitochondrial myopathies were photographed and appended in the AMR Web site and could be viewed at http://www.amr-seminar.org/seminar/61/images.php.
Histopathologic Features On haematoxylin and eosin, the muscle exhibited a normal architecture. The myocytes were mostly uniform in size, had polygonal contours, and normally placed peripheral nuclei. However, on this apparent normal background a few scattered abnormally stained myocytes with irregular cell contours could also be seen (Fig. 1A). No necrotic fibers or inflammatory infiltrates were seen. Verhoeff van Gieson stain showed physiologic amounts of interstitial collagen, and PAS with and without diastase digestion showed no significant increased glycogen content. Gomori trichrome highlighted patchily distributed ragged-red fibers (10% of the total), that is, fibers with irregular subsarcolemmal rims of reddish material, indicating subsarcolemmal accumulation of mitochondria (Figs. 1B–F). The sequential COX-SDH stained sections showed scattered hyper-reactive dark-blue fibers (20% of the total), corresponding to those fibers with mitochondrial hyperplasia and COX activity deficiency, on a background of grey-brown fibers (Fig. 2). Nicotine adenine dinucleotide dehydrogenase tetrazolium reductase stain, which evaluates the activity of complex I (encoded by both nuclear and mitochondrial DNA), revealed some hyper-reactive dark fibers (10% of the total). Myosin ATPase reactions showed normal type I and type II fibers, predominately slow-twitch type I fibers, in accordance with the biopsy site (deltoid muscle). The rest of the enzymatic stains highlighted a normal activity of the intermyofibrillary network. Oil-red-O and Sudan black stains revealed slight increased neutral lipid droplets in the myocytes.
Ultrastructural Features The salient finding was supernumerary subsarcolemmal and intermyofibrillar collections of mitochondria. These organelles were unduly large and pleomorphic and often contained paracrystalline inclusions between the inner and outer membranes of the mitochondrial walls, replacing the cristae. These paracrystalline inclusions were frequently multiple and arranged in parallel rows (parking-lot inclusions) and consisted of rectangular arrays of mitochondrial membranes in a linear or grid-like pattern. Occasionally the mitochondrial membranes were arranged in whorls. A few intramitochondrial osmiophilic dense bodies in the matrix were also seen (Figs. 3, 4). Other pathologic findings were focal and moderate lysis of the sarcolemmal myofibrils as well as focal and moderate increase of the cytoplasmic lipid and glycogen content.
Clinicopathologic Diagnosis On the basis of clinical, histologic, histoenzymatic, and ultrastructural findings the diagnosis of mitochondrial myopathy presenting with chronic progressive external ophthalmoplegia (CPEO) in association with moderate proximal myopathy was made. r
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Progressive External Ophthalmoplegia
FIGURE 1. Deltoid muscle, cross section. (A, hematoxylin and eosin; B–F, Gomori trichrome stain). (A) Well-preserved striated muscle architecture. Three myocytes with irregular structure and/or abnormal staining (arrows) among the normal ones. (B–F) Patchy distribution of ragged-red fibers. Subsarcolemmal rims of bright red or red-blue material, which correspond to accumulated hypertrophic and hyperplastic mitochondria: Inset in (F): ragged-red fiber at higher magnification.
AUTHOR’S COMMENT Mitochondria are the main source of energy production in mammalian cells and accordingly primary mitochondrial disorders, affecting the respiratory chain’s ability to undergo oxidative phosphorylation and leading to r
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decreased production of ATP, clinically involve tissues with the highest energy requirements, such as the nervous, muscular, cardiac, and endocrine systems. Mitochondrial myopathies (MM) are mitochondrial disorders, caused by mutations in both the nuclear and www.anatomicpathology.com |
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FIGURE 2. (A–F) COX-SDH double-staining method. Cross-section of striated muscle with many grey-blue affected myocytes, showing a mosaic pattern as seen in patients with mtDNA disorders. These grey-blue fibers are COX negative and correspond to the ragged-red fibers seen in Figure 1. The grey-blue staining tinctorial appearance is because of preserved enzymatic reactivity of supernumerary mitochondria for SDH. COX-SDH indicates cytochrome c oxydase-succinate dehydrogenase.
mitochondrial genomes, featuring myopathy, which may occur at any age with a prevalence of approximately 1 in 10,000 people.1 Involvement of the external ocular muscles (ocular myopathy), including levator palpebrae and extrinsic eye
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muscles, and manifesting as symmetric, bilateral palpebral ptosis and ophthalmoparesis, is a main feature of various MM, and is the dominant symptom in CPEO, a condition, also known as progressive external ophthalmoplegia (PEO), which may present from childhood up to late adulthood.2 r
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Progressive External Ophthalmoplegia
FIGURE 3. Ragged-red fiber. Electron microscopical analysis. (A) Moderate lysis of contractile elements and an osmiophilic dense body ( 3000). (B) The sarcoplasm contains pleomorphic mitochondria, some smaller than normal (arrowheads) and others large and emptyappearing with degraded cristae ( 6000). (C) Subsarcolemmal accumulation of mitochondria with scattered, rectangular electron dense material (arrows) and a few large lipid droplets (asterisks). ( 6000) (D) The dense material in the mitochondrial matrix are paracrystalline inclusions ( 18,000).
PEO is a relatively mild form of MM, characterized by blepharoptosis and ophthalmoplegia, almost always in the absence of diplopia, pain, proptosis, and pupil involvement, which may clinically manifest in a pure form or in association with proximal myopathy.2–4 In either case PEO is always a systemic disease as is attested to by the presence of mitochondrial abnormalities seen in biopsies, taken from muscle other than the extrinsic eye muscle (usually the deltoid or quadriceps muscle). In our patient the MM involved exclusively the muscular system and manifested with PEO, as the most important symptom, in association with moderate proximal myopathy. r
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PEO can either be maternally inherited, both from asymptomatic or clinically affected mothers, or arise de novo in the proband. Other symptoms deriving from the multisystem mitochondrial involvement may be either absent in PEO or variably present to a mild degree. PEO can also be part of other more complex mitochondrial syndromes with severe multi-organ dysfunction, such as Kearns-Sayre syndrome (occurring in the young mainly in association with pigmentary retinopathy, cardiac conduction disorders, and diabetes mellitus), sensory ataxic neuropathy, dysarthria, and ophtalmoparesis, various forms of ataxia neuropathy syndromes, and mitochondrial www.anatomicpathology.com |
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FIGURE 4. Ragged-red fiber. Electron microscopical analysis. (A–C) Intramitochondrial crystal-like inclusions arranged in parallel rows within the intermembrane compartment (“parking lot” inclusions). The mitochondria containing paracrystalline inclusions are devoid of cristae. The myofibrillar architecture in (A) is still relatively preserved, whereas in (B and C) is severely altered with disarray and fragmentation of myofibrils. Prominent lipid droplets are also seen in (A and B). In the right lower corner of (C) is a cell membrane (sarcolemma) of a myocyte with a small portion of the endomysium. [magnifications: A, ( 9000); B, ( 12,000); C, ( 23,000)] Inset in (B): paracrystalline inclusion with arrays of mitochondrial cristal membranes in a linear pattern. Inset in (C): higher magnification of the crystal-like inclusions indicated with arrow, showing rectangular arrays of mitochondrial membranes arranged in a grid-like pattern (original magnification 12,000, and 18,000, respectively) (D) Subsarcolemmal accumulation of mitochondria with thin curvilinear arrays of paracrystalline membranes, visible in the outer compartment space between the inner and outer mitochondrial membrane. The cell membrane, endomysium, and an adjacent portion of an apparently preserved muscle fiber are seen at the upper left part of the picture ( 18,000). Inset in (D): mitochondrial cristae arranged in a whorl of parallel membranes (original magnification 18,000).
neurogastrointestinal encephalopathy, which are all diagnosed on skeletal muscle biopsy.2 Incidentally, mitochondrial neurogastrointestinal encephalopathy can also be diagnosed or suspected with gastrointestinal biopsy, as characteristic megamitochondria have been reported in gastrointestinal ganglion and smooth muscle cells.5
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Mitochondrial disorders occasionally manifest as polyneuropathy either as the dominant feature or as one of many other manifestations (inherited mitochondrial neuropathy).6 Mitochondrial disorders, in which polyneuropathy is the dominant feature, include a syndromic form (socalled NARP, neuropathy, ataxia, retinitis r
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pigmentosa) and a few other inherited mitochondrial neuropathies, one of which manifests in association with PEO (mixed axonal and demyelinating sensori-motor neuropathy with PEO).6 However, some MM (around a third of the total) do not typically present with ocular myopathy, such as myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS) and myoclonus, epilepsy, and ragged-red fibers (MERFF), the 2 best known clinically systemic MM, which may also be associated with additional symptoms (ie, ataxia and cardiomyopathy in both, and deafness and endocrinopathy in the former).2 Other MM not associated with ocular myopathy are some forms of ataxia neuropathy syndromes, some forms of isolated MM, and some forms of infantile MM.2 MM have diverse genetic etiologies with a poor genotype-phenotype correlation, with the same mutation presenting highly variable phenotypes both within and between families (this is because of heteroplasmy). MM also exhibits a highly variable pattern of inheritance. Molecular analysis of mtDNA may either show point mutations and single large-scale deletions or depletions and multiple deletions, the latter as secondary effects of mutations involving nuclear genes encoding subunits of the mitochondrial respiratory chain, structural mitochondrial proteins, proteins for mitochondrial maintance, and/or proteins for intergenomic communication.2,7–13 Regarding the clinical approach to ocular myopathy there are a few considerations to be taken into account: (1) ocular myopathy, mainly palpebral ptosis can be of various origins14; (2) all patients with ocular myopathy should be suspected to harbour MM; (3) in some of these patients myopathy can be overshadowed by other clinical manifestations; (4) ocular myopathy in MM is of long-standing duration (this excludes some forms of eye muscle paresis of acute onset, such as botulism); (5) all patients with suspected MM should undergo cardiac, endocrine, auditory, and visual investigations; (6) some patients who present with mitochondrial symptoms, including ocular myopathy, may not have a primary mitochondrial disease (as occurs with exposure to toxins, including some medications that affect mitochondrial function).7 Extrinsic eye muscles have fundamentally distinct properties that make them selectively vulnerable to certain neuromuscular disorders.15,16 These muscles contain a much greater volume of mitochondria than any other muscle group, and this results in their preferential clinical involvement in MM, which occurs in around two thirds of affected patients. The clinical differential diagnosis of PEO includes several diseases, such as myastenic syndromes, ocular myositis, thyroid associated orbitopathy, and a few primary dystrophic myopathies, such as oculopharyngeal muscular dystrophy16–18 and myotonic dystrophy,16,18,19 and occasionally also facioscapulohumeral dystrophy16 and limb girdle muscular dystrophy.20 Myasthenia gravis is the main differential diagnostic consideration of all: in fact, although this disease has specific clinical distinguishing features (eg, fluctuant ophthalmoplegia, asymmetrical palpebral ptosis, diplopia, and weakness of the orbicularis oculi muscles) and its diagnosis is confirmed by the presence of anti-acetylcholine receptor and/or anti-muscle specific tyrosine kinase receptor antibodies, patients presenting with atypical forms of PEO may still be misdiagnosed with myasthenia gravis21–24 and r
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Progressive External Ophthalmoplegia
undergo unnecessary thymectomy.22 Eye muscle involvement is uncommon but may also occur in Lambert-Eaton syndrome, which is another myasthenic disorder, often of paraneoplastic origin (small cell carcinoma of lung), to be considered in adults, which is caused by antibodies directed to the voltage-gated calcium channels at the neuromuscular junctions. Muscle biopsy is the main diagnostic tool to correctly diagnose MM, including PEO. Of note, 2 relatives in our patient’s family, who were likely affected by MM and did not undergo muscle biopsy, had previously been clinically diagnosed with muscular dystrophy-NOS. The major diagnostic features of mitochondrial myopathy are: (I) the presence of a substantial number of COXnegative fibers (> 5% of the total muscle fibers) as seen by histoenzymatic analysis and/or by the equivalent raggedred fibers as seen with Gomori stain, and (II) the ultrastructural detection of hyperplastic and abnormal mitochondria with characteristic paracrystalline inclusions. Histologically, there are 2 main patterns of morphologic changes suggesting to the pathologist whether the molecular etiology is a primary defect of mtDNA or a primary defect of nDNA: as a general rule, when COX-deficient fibers are scattered in a mosaic-pattern, mtDNA mutation is suggested, whereas when COX is uniformly decreased in muscle fibers a nDNA mutation is likely. However, the pathologist should be aware of the rare occurrence in which the biochemical defect of MM does not involve complex IV/COX, and in these cases the histoenzymatic analysis is normal. Electron microscopy is fundamental, both as a confirmatory and a complementary diagnostic tool in these diseases. Medical treatment is limited, including administration of vitamins and cofactors, but newer therapies are being investigated.2,9,11,25,26 Plastic surgery aiming to correct palpebral ptosis can be suggested in the most severe forms, although postoperative complications (mainly corneal exposure and ulceration) have also been recorded.18,24,27,28
Follow-up In this case the molecular analysis of mtDNA, which was performed for MERFF, MELAS, NARP, and KearnsSayre syndromes, and the direct sequencing of tRNAleuc and tRNAlys nuclear genes did not disclose any mutation. Because a negative molecular analysis does not exclude MM, our diagnosis remains unchanged. The patient was given supplementation therapy with Lcarnitine29,30 and coenzyme Q10.31 At present, 8 years after diagnosis, the disease is stable. Now, we cannot exclude the possibility that her MM was due to primary Co Q10 deficiency.
CLUB’S OPINIONS Beautiful case, thanks for giving us the opportunity to see this rare type of myopathy. The stain is fascinating. Mitochondrial myopathy associated with progressive external ophthalmoplegia. Thanks for the encyclopaedic discussion. Thanks for the case with such incredible discussion. I have the Gomori stained slide (marked A underneath the label) and seen many small red specks which remind me of AFB seen with Z-N. Can neither agree nor disagree with the diagnosis since it will be a cold day in hell when I am able to interpret www.anatomicpathology.com |
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frozen sections of muscle. This appears to be a beautiful discussion although I must admit I am not confident enough to understand half of it. “Ragged-red fibers” and “parking lot bodies” takes me many years back. Lovely stain! Our specialist for EM & muscle biopsies agrees that on the basis of the case history, HC and EM this is a classical example of mitochondrial myopathy with PEO. Wow! How very interesting! No wonder the neurologists keep that area for themselves at our hospital. Mitochondrial myopathy presenting with progressive external ophthalmoplegia (PEO). This is a typical case of neuromuscular disease of which I have just elementary education. This area of pathology is currently managed by neurologists. Still I appreciated very much receiving your slide and seeing in AMR website the pictures of both stains (Gomori stain as well as COX-SDH stain), which clearly shows the enzymatic mitochondrial defect, underlying this type of primary myopathy. Mitochondrial myopathy, very informative account— thank you. Typical case of mitochondrial myopathy. Thank you for such a good documented case. I appreciate your endless (and fruitless, sadly to say) efforts to educate people like me. Is there any field of pathology you have no expertise on? Highly educational case. Great discussion. Thank you very much. Interesting case of mitocondrial myopathy, and nice discussion, thank you. No comments, extraordinary documentation. Thank you for this treatise on mitochondrial myopathies. I have no experience with muscle biopsy interpretation. This brings back memories of muscle biopsy days and looking at the ultrastructure of these cases of mitochondrial myopathy. It must be at least 20 years since I have seen a muscle biopsy now. Thanks for the encyclopaedic review. It was clear in reading your dissertation that this field has well and truly passed me by! REFERENCES
1. Schaefer AM, McFarland R, Blakely EL, et al. Prevalence of mitochondrial DNA disease in adults. Ann Neurol. 2008;63: 35–39. 2. Pfeffer G, Chinnery PF. Diagnosis and treatment of mitochondrial myopathies. Ann Med. 2013;45:4–16. 3. Serratrice G, Pellissier JF. [Ocular myopathies. Nosological study of 49 cases]. Presse Med. 1987;16:1969–1974. 4. Serratrice G, Pellissier JF, Desnuelle C, et al. Mitochondrial and ocular myopathies (62 cases). Rev Neurol (Paris). 1991;147:474–475. 5. Perez-Atayde AR. Diagnosis of mitochondrial neurogastrointestinal encephalopathy disease in gastrointestinal biopsies. Hum Pathol. 2013;44:1440–1446. 6. Finsterer J. Inherited mitochondrial neuropathies. J Neurol Sci. 2011;304:9–16. 7. Cohen BH. Neuromuscular and systemic presentations in adults: diagnoses beyond MERRF and MELAS. Neurotherapeutics. 2013;10:227–242.
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8. DiMauro S, Hirano M. Mitochondrial encephalomyopathies: an update. Neuromuscul Disord. 2005;15:276–286. 9. DiMauro S. Pathogenesis and treatment of mitochondrial myopathies: recent advances. Acta Myol. 2010;29:333–338. 10. DiMauro S. Mitochondrial encephalomyopathies—fifty years on: the Robert Wartenberg Lecture. Neurology. 2013;81: 281–291. 11. DiMauro S, Schon EA, Carelli V, et al. The clinical maze of mitochondrial neurology. Nat Rev Neurol. 2013;9:429–444. 12. Goldstein AC, Bhatia P, Vento JM. Mitochondrial disease in childhood: nuclear encoded. Neurotherapeutics. 2013;10: 212–226. 13. Servidei S. Mitochondrial encephalomyopathies: gene mutation. Neuromuscul Disord. 2004;14:107–116. 14. Clauser L, Tieghi R, Galie` M. Palpebral ptosis: clinical classification, differential diagnosis, and surgical guidelines: an overview. J Craniofac Surg. 2006;17:246–254. 15. Farrugia ME. Myasthenic syndromes. J R Coll Physicians Edinb. 2011;41:43–47. 16. Pe´nisson-Besnier I, Lamirel C. Ocular disturbances in neuromuscular disorders. Rev Neurol (Paris). 2008;164:902–911. 17. Gautier D, Pe´nisson-Besnier I, Rivaud-Pe´choux S, et al. Ocular motor deficits in oculopharyngeal muscular dystrophy. Eur J Neurol. 2012;19:e38. 18. Doherty M, Winterton R, Griffiths PG. Eyelid surgery in ocular myopathies. Orbit. 2013;32:12–15. 19. Thiriez C, Vignal C, Papeix C, et al. Ophthalmoplegia as the presenting muscle-related manifestation of myotonic dystrophy. Rev Neurol (Paris). 2010;166:538–541. 20. Filosto M, Tonin P, Vattemi G, et al. Chronic ophthalmoparesis in limb girdle muscular dystrophy 1C. J Neurol Neurosurg Psychiatry. 2009;80:448–449. 21. Barton JJ, Maguire J, Mezei M, et al. Mitochondrial pseudomyasthenia. J Neuro Ophthalmol. 2010;30:248–251. 22. Ben Yaou R, Laforeˆt P, Be´cane HM, et al. Misdiagnosis of mitochondrial myopathies: a study of 12 thymectomized patients. Rev Neurol (Paris). 2006;162:339–346. 23. Owens WE, Gupta D, Bertorini T. Enhancement of contralateral ptosis on passively holding an eyelid in mitochondrial myopathy resembling myasthenia gravis. J Clin Neuromuscul Dis. 2005;6:188–190. 24. Schoser BG, Pongratz D. Extraocular mitochondrial myopathies and their differential diagnoses. Strabismus. 2006;14: 107–113. 25. Lee AG, Brazis PW. Chronic progressive external ophthalmoplegia. Curr Neurol Neurosci Rep. 2002;2:413–417. 26. Scarpelli M, Cotelli MS, Mancuso M, et al. Current options in the treatment of mitochondrial diseases. Recent Pat CNS Drug Discov. 2010;5:203–210. 27. Lucci LM, Fonseca Junior NL, Sugano DM, et al. Tarsal switch levator for mitochondrial myogenic ptosis. Arq Bras Oftalmol. 2009;72:159–163. 28. Soejima K, Sakurai H, Nozaki M, et al. Surgical treatment of blepharoptosis caused by chronic progressive external ophthalmoplegia. Ann Plast Surg. 2006;56:439–442. 29. Gimenes AC, Napolis LM, Silva NL, et al. The effect of Lcarnitine supplementation on respiratory muscle strength and exercise tolerance in patients with mitochondrial myopathies. [Abstract]. Eur Respir J. 2007;51(suppl):21S[E297]. 30. Gallagher CL, Waclawik AJ, Beinlich BR, et al. Friedreich’s ataxia associated with mitochondrial myopathy: clinicopathologic report. J Child Neurol. 2002;17:453–456. 31. Montini G, Malaventura C, Salviati L. Early coenzyme Q10 supplementation in primary coenzyme Q10 defi ciency. N Engl J Med. 2008;358:2849–2850.
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