Ann 0/01 Rhirwl Laryngol 101:1992

SOLITARY PLASMACYTOMA OF THE SKULL BASE JOE MARAIS, MB,BCH, FRCS EDThffiURGH, SCOTLAND

GERALD B. BROOKES, FRCS

CHIN-CHENG LEE, MD

LONDON, ENGLAND

LONDON, ENGLAND

Plasmacytomas involving the skull base are rare lesions that may be well advanced by the time of diagnosis. Because of their anatomic site they may produce a variety of signs and symptoms, some of which may be vague, often resulting in delays in presentation and in appropriate investigations. We present such a patient, discuss the diagnosis and management, and give a review of the literature.

KEY WORDS - immunocytochemical staining, plasmacytoma, skull base.

rate of 12 mm/h and a normal full blood count. The urea, electrolyte, glucose, and liver functions, as well as the results of the Treponemapallidum hemagglutination assay, were normal. Serum protein electrophoresis showed increased alpha-l , alpha- 2, and beta globulins. Urinalysis was negative for glucose, ketones, and Bence-Jones proteins. A bone marrow aspirate revealed only normal elements.

Plasma cell tumors occurring in the head and neck may be solitary or multifocal, and Batsakis! classified them in the following manner: 1) a manifestation of multiple myeloma, 2) a manifestation of plasma cell myelomatosis, 3) solitary plasmacytoma of the bone, or 4) extramedullary plasmacytoma (primary plasmacytoma of soft tissues). The incidence of multiple myeloma greatly exceeds that ofextramedullary plasma cell tumors, I and tumors of this nature localized to the skull base are extremely rare. 2,3 Although 80% of these tumors are found in the head and neck, they more commonly occur in the nose, paranasal sinuses, nasopharynx, and tonsils. I

The chest radiograph was normal, but plain skull films showed areas of lucency in the skull base. A computed tomogram of the skull base (see Figure, A) showed a large mass arising from the region of the basisphenoid and extending forward into the sphenoid sinuses and superiorly up through the pituitary fossa to involve the parasellar regions and both the cavernous sinuses. Some extension backward along the tentorial margin on the left was noted, where a large nodule of tissue could be seen projecting toward the left side of the brain stem. Considerable bone destruction was observed. The lesion was predominantly hyperdense, but some enhancement with contrast was noted. A whole body bone scan revealed no other site of bony involvement.

CASE REPORT

The patient, a 64-year-old man, presented with an 18-month history of intermittent horizontal diplopia and a 6-month history of severe right frontal headache. He was assessed at an optometry clinic, where he was fitted with a lens for the right eye, and the diplopia resolved. The headaches, however, became increasingly severe over the ensuing 6 to 8 months and he consulted his general practitioner, who referred him for a neurologic opinion.

The patient underwent a transsphenoidal biopsy of the mass and made an uneventful recovery. Histologic examination showed a tumor consisting of aggregates ofplasma cells separated by thin fibrovascular septa (see Figure, B). Tumor cells were welldifferentiated, mature cells with eccentric nuclei and showed the characteristic cartwheel arrangement of nuclear chromatin. There was some degree of nuclear pleomorphism, and a number of cells were binucleated or multinucleated, although mitotic activity was not a feature. No Russell bodies were observed. Methyl green pyronin staining demonstrated strongly pyroninophilic cytoplasm in most tumor cells, but Congo

On examination, the patient was generally well. His speech, gait, and musculoskeletal systems were normal and there was no loss of weight. His visual fields, fundi, eye movements, and pupillary reactions were normal. No diplopia could be demonstrated. The rest of the cranial nerves were also normal. Findings on indirect nasopharyngoscopy were normal and no cervical lymphadenopathy was noted. The rest ofthe otolaryngologic, neurologic, and cardiorespiratory examination revealed no abnormality. Blood tests showed an erythrocyte sedimentation

From The Royal National Throat, Nose and Ear Hospital, London, England. Dr Marais is now in the Department of Otolaryngology, The Royal Infirmary, Edinburgh, Scotland.

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Solitaryplasmacytoma of skullbase. A) High-resolutioncomputed tomogram of skull base demonstrating large space-occupying lesion that can be seen projecting posteriorly toward brain stem. B) Photomicrograph of ~u~or showing aggregates of well-differentiated plasma cells (H & E, original x33). C) Photomicrograph of immunocytochemically stained tumor demonstrating cells with thin rim of cytoplasm positive for L-26 (arrows) specific for B-celllymphocytes (original x33).

B red staining did not reveal any amyloid. Immunohistochemical techniques were applied by using the following antibodies and the avidin-biotin complex method": cytokeratin, Becton Dickinson dcsmin, L-26, UCHLI, common leukocyte antibody, and K and A light chain (all Dako, United Kingdom). They showed tumor cells reacting positively to antibodies to common leukocyte antigen, L-26, and K light chain. The patient was treated by radiotherapy with 44 Gy in 22 fractions and, after 18 months of follow-up, remains symptom-free with no sign of multiple myeloma. DISCUSSION

The diagnosis of solitary plasmacytoma of bone can never be absolutely certain on the basis of pathologic examination of marrow aspirates, as in-

volvement of marrow may be patchy. It is therefore possible that some patients with an apparently solitary lesion actually have occult multiple myeloma. Patients with solitary lesions on presentation must therefore have lifelong follow-up to detect the manifestations of occult disease. As noted by Woodruff et al,5 the very long survival of some individuals with solitary lesions in bone implies that these lesions are indeed solitary. Extramedullary lesions are more commonly solitary, and three quarters of these lesions occur in patients between 40 and 70 years of age, with a male to female ratio of 4: 1. Clarke" has offered a clinical classification of cranial and extracranial plasmacytomas as follows: 1) syndromes of cranial nerve palsy, 2) intracranial tumor syndromes, and 3) intraorbital tumor syndromes. Clarke has also noted that the most commonly involved cranial nerves are the abducent and the

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Marais et al, Skull Base Plasmacytoma

vestibulocochlear nerves. Clearly, this classification does not allow for small tumors that have not resulted in the development of such syndromes, but which are currently easily visualized by high-resolution tomography and magnetic resonance imaging. Solitary plasmacytomas are macroscopically variable in appearance, ranging from tannish pink to deep red in color, and may be polypoidal or sessile, becoming lobulated as size increases. I Histologically they must be differentiated from plasma cell granulomas and meningiomas with plasma cell infiltrations. Plasmacytomas are virtually monomorphic and only very rarely contain Russell bodies. These are intracytoplasmic accumulations ofstrongly eosinophilic, periodic acid-Schiff-positive material. These structures are more common in plasma cell aggregates associated with chronic inflammation, and their absence is therefore an important negative observation in the presented case. Immunocytochemical study with antibodies to K and A chains is an important approach to the evaluation of a suspected plasmacytoma." Monoclonality, as evidenced by a predominant population of cells with cytoplasmic K or A chain reactivity, confirms a plasmacytoma. In lesions involving the skull base this is particularly helpful, as local inflammatory responses may otherwise result in errors in diagnosis. This technique has quite clearly demonstrated the nature of the lesion in the presented case (see Figure, C). Amyloid has been shown to occur in some plasmacytomas, but was not found in the current case. In the 10 cases of solitary intracranial plasmacytoma (SIP) involving the skull base reviewed by Mancardi and Mandybur.f its presence was not reported, and it was noted in only 4 of the 15 recorded cases of SIP involving the meninges or parenchymal nervous tissue. The significance of amyloid in these lesions is unclear, and although it occurs in 20% of solitary plasmacytomas of the respiratory tract.? it does not appear to affect the outcome of intracranial or skull base lesions. I None of the 10 skull base SIPs reviewed by Mancardi and Mandybur had been studied immunohistochemically, and only three of the meningeal or parenchymatous lesions, 8.10, II including their reported case, were examined by this technique, confirming the monoclonal nature of the lesion. Toland and Phelps.l- reporting one of the cases reviewed by Mancardi and Mandybur, have outlined the radiographic features of skull base SIPs. They are usually large and osteolytic and may be one of two varieties: 1) multicystic areas of rarefaction with

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sharply defined margins and irregular and sometimes thick trabeculae or 2) destructive, nontrabeculated areas that closely resemble metastatic disease. Despite the above observations, there are no diagnostic radiographic features of these tumors, as the above findings may be produced by other lesions involving the skull base, including chordomas. metastases, nasopharyngeal tumors. eosinophilic granulomas. glomus tumors, meningiomas, and epidermoid tumors. In the presented case, the pattern ofdestruction most closely resembled that described in the second category, and a preoperative radiologic diagnosis of chordoma was made, emphasizing this point. It is generally accepted by many authors that precise localization of the primary site may be difficult because of the size of the lesion and the destructive changes present, and this is clearly the situation in the presented case. Toland and Phelps 12 have noted that tumors involving the bones of the skull base only rarely invade the dura and that extension into parenchymal brain has not been seen.

The assessment of the aggressiveness of solitary extramedullary plasmacytomas must be cautious, as the cytoplasmic indices normally used do not correlate with biologic tumor behavior. I Bony erosion is a characteristic of more aggressive tumors, and patients who suffer recurrence or persistence of their primary tumor after treatment tend to do worse than those who have no bone destruction. Regional lymphadenopathy does not seem to imply a worse prognosis. Woodruff et al'' have reported their follow-up of 16 patients with extramedullary solitary plasmacytomas involving the head and neck, collected over a 21-year period. Their follow-up periods extended up to 16 years, and 8 patients were followed up for at least 2 years. Patients all received radiotherapy with doses between 25 and 50 Gy. Only 1 patient developed local recurrence, and another developed disseminated disease. They therefore recommend radiotherapy as the treatment of choice and highlight the favorable prognosis in patients with head or neck lesions as opposed to those with plasmacytomas in other sites. Batsakis, I however, states that radiosensitivity of such tumors is not a uniform characteristic and points out that there is no clear evidence of superiority ofone form of treatment over another. Treatment should therefore be individualized by taking into account locally available facilities as well as the size and site of the tumor and patient factors. The subtyping of extramedullary plasmacytomas by immunohistochemical techniques and extended follow-up of patients treated by various modalities may allow correlation between tumor types and out-

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come once sufficient cases have been analyzed. It is therefore suggested that these techniques should be routinely employed in all tumors of this nature. SUMMARY

Solitary extramedullary plasmacytomas ofthe skull ACKNOWLEDGMENTS -

base are a rare clinical entity, and little is known of their biologic behavior. We present a patient with a large lesion ofthis type involving the skull base who remains well 18 months after treatment with radiotherapy. A review of the diagnosis and management of the condition is discussed.

The authors thank F. Scaravilli, MD, PhD, G. Gould, and Anne White for their help in the preparation of this report.

REFERENCES 1. Batsakis JG. Tumors of the head and neck. 2nd ed. Baltimore, Md: Williams & Wilkins, 1979:471-5. 2. Russell DS, Rubenstein U. Pathology of tumours of the nervous system. 2nd ed. London, England: Edward Arnold, 1969:111-2. 3. Henson RA, Urich H. Cancer and the nervous system. Oxford, England: Blackwell Scientific, 1982:184-95. 4. Sobel RA, Blanchette GW, Bhaw AK, Colvin RB. The immunopathology of experimental allergic encephalomyelitis I. Quantitative analysis of inflammatory cells in situ. J Immunol 1984;132:2393-401. 5. Woodruff RK, Whittle 1M, Malpes JS. Solitary plasmacytoma I: Extramedullary soft tissue plasmacytoma and II: Solitary plasmacytoma of bone. Cancer 1979;43:2340-7. 6. Clarke E. Cranial and intracranial myelomas. Brain 1954;

77:61-72. 7. Rosai 1. Tumors of the lymphoreticular system. In: Rosai J, ed. Ackerman's Surgical pathology. Vol 2. 6th ed. St Louis, Mo: CV Mosby, 1981:1555-636. 8. Mancardi GL, Mandybur TI. Solitary intracranial plasmacytoma. Cancer 1983;51:2226-33. 9. Michaels L, Hyams V1. Amyloid in localised deposits and plasmacytomas of the respiratory tract. J Patho11979; 128:29-38. 10. Case records of the Massachusetts General Hospital(1973). N Engl J Med 1973;288: 150-6. 11. Mancilla-Jimenez R, Tavassoli FA. Solitary meningeal plasmacytoma: report of a case with electron microscopic and immunohistologic observations. Cancer 1976;38:798-806. 12. Toland J, Phelps PD. Plasmacytoma of the skull base. Clin RadioI1971;22:93-6.

FIRST INTERNATIONAL CONFERENCE ON ELECTROCOCHLEOGRAPHY AND MONITORING The First International Conference on Electrocochleography and Monitoring will be held Sept 20-24, 1992, in Wurzburg, Germany. For further information, contact Program Chairman, Dr. Dirk Hoehmann, Dept of Otolaryngology, University of Wurzburg Medical School, Josef-Schneider-Str 11, D-8700, Wurzburg, Germany; telephone 49-931-201-2323, or fax 49-931-201-2248.

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Solitary plasmacytoma of the skull base.

Plasmacytomas involving the skull base are rare lesions that may be well advanced by the time of diagnosis. Because of their anatomic site they may pr...
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