British Journal of Neurosurgey (1990) 4, 2 11-2 16
ORIGINAL ARTICLE
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid tumours: thirty-seven years of diagnosis and treatment LIANG-FU ZHOU
Institute of Neurology, Department of Neurosurgery, Shanghai Medical University, Shanghai, People’s Republic of China
Abstract The clinical, operative and pathological characteristics of 102 consecutive cases of intracranial epidermoid tumours are reported. These cases constituted 1.1% of all intracranial turnours and 13.5% of congenital neoplasma admitted to our service in the period 1951-88. Of 91 (89.2%) intradural tumours, 74 (72.5%) were in the subarachnoid cisterns, especially in the cerebellopontine angle cistern (31 cases). The tumours were solid in 69 cases (67.6%) and cystic in 26 (25.5%); the remaining 7 cases were not recorded. There were no specific clinical features with which to identify the nature and extent of the tumour. Diagnosis and treatment are described, with an evaluation of CT and MRI. Before 1981, total removal rate of tumour was 29.3%; after that date it was 72.7% with the aid of microsurgery. The overall surgical mortality rate was 4.9% (5 cases), but there were no deaths in the microsurgical group. Follow-up for a period of 0.5-37 years (mean 13 years) was carried out in 68 patients (70.1%). Among 24 patients with incomplete removal, recurrence of tumour was verified in 4 cases; 3 underwent reoperation with excellent or good results. One patient refused operation and died. All the remaining 20 cases, save 3 who died of other diseases, returned to their normal activities without recurrent manifestations. The results suggest that the primary treatment of epidermoid turnours should be surgical removal including the contents and capsule of a tumour. With the aid of microsurgical technique, complete removal is possible. Patients with incomplete removal can also obtain a long-term favourable result. Key words: Intracranial epidermoid tumour, diagnosis treatment.
66 years, mean 38.6 years. The duration of disease up to the time of admission was from 1 month to 15 years, mean 3.5 years. The lesions in all patients were proved histologically and their locations are shown in Table I.
Introduction Epidermoid tumour is a common congenital tumour, and constitutes approximately 0.2-1 % of all intracranial turn our^.*-*^^ During a period of 37 years, 1951-88, 102 patients were admitted to our Institute for treatment. In the present paper, we summarize our experience in the diagnosis, treatment and long-term followup, with a review of the relevant literature.
Symptoms and signs The clinical manifestations in 102 patients are set out in Table 11.
Clinical data Of 102 patients, 64 were males and 38 females, a sex ratio of 1.7:1. Their ages ranged from 7 to
Diagnostic investigations
21 I
Because computed tomography (CT) was not
212
Liang-fu Zhou
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
'TABLE I. T h e location of 102 cases of intracranial epidermoid turnours* (%) Intradural (91 cases)
89.2
Extradural (1 1 cases) anterior cranial fossa (5) middle cranial fossa (5) posterior cranial fossa (1)
10.8
Intraventricular (6 cases) lateral V (1) 3rd V (2) 4th V (3)
5.9
Intracerebral (1 1 cases) supratentorial (4) infratentorial (7)
10.8
Cisternal (74 cases) suprasellar (8) callosal (2) parasello-Sylvian (10) C P angle (3 1 ) parasello-CP angle (8) post-3rd V clivus (9)
72.5
*V, ventricle; CP, cerebello-pontine.
TABLE 11. Clinical manifestations in 102 patients 64 cases Headache or dizziness 8 cases Eye pain 4 cases Anosmia Papilloedema (with or without secondary optic 14 cases atrophy and visual field defect) 2 cases Foster-Kennedy syndrome Proptosis and limitation of extraocular move- 10 cases ment 8 cases Diplopia 16 cases Tic douloureux Trigeminal hypaesthesia 38 cases 12 cases Temporal muscle atrophy IXth-XIIth cranial nerve palsies 24 cases 10 cases Nystagmus 34 cases Ataxia 30 cases Positive pyramidal signs 10 cases Hemiplegia 6 cases Hemidysesthesia 8 cases Disturbances of endocrine function (including sexual inability, amenorrhoea and growth retardation) 12 cases Grand ma1 epilepsy 2 cases Facial pigmentation 1 case Skin neurofibromatosis
used in our Institute until 1980, 51 patients (50%) underwent the following neuroradiological examinations:
Radiology of skull (27 cases). Normal in 11 cases, with signs of intracranial hypertension in 15 cases, dilatation of internal auditory meatus in 1 case. Cerebral angiography (15 cases). Cerebral vessels compressed and shifted with signs of space-occupying lesion were seen in 12 cases. Pneumoencephalography (34 cases) and ventriculography (7 cases). Compression, distortion, shift and obliteration of ventricles or cisterns were noted in 32 and 6 cases respectively. CT (51 cases). In 47 cases, there was a low density lesion with or without calcification around or within the lesion. In the remaining 4, there was a high-density lesion. All of the 51 cases presented no change after enhancement (Figs. 1, 2). I n the past two years, magnetic resonance imaging (MRI) has been used in 6 cases. In all there was a high signal T1- and T 2 image of an extra-axial tumour (Fig. 3). Pathology Macroscopically, all tumours, except seven with insufficient data, can be divided into two groups: Solid tumour (69 cases). These were white in colour, with the lustre of pearls. The walls of the tumours were transparent and fragile. They contained cheesy material made up of desquamated cells and keratin with a small amount of white liquid. Cystic tumour (26 cases). T h e capsules were smooth and transparent, the colour varied with the contents which were white in 2 cases, butter-yellow in 6 cases, brown in 10 cases and ink-green in 8 cases. T h e contents varied from watery to thick material like tar, which quickly coagulated into an agar-like substance when exposed to air. T h e
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid tumours, diagnosis and treatment
2 13
FIG. 1. Pre- (left) and postenhanced (right) C T scans, showing typical unenhanced hypodense lesion of posterior 3rd ventricle.
FIG. 2. Pre- (left) and postoperative (right) C T scans of a non-enhancing hyperdense lesion of posterior 3rd ventricle.
FIG. 3. T1- (left) and T2-image (right) of MRI showing a high signal clival epidermoid with symmetrical growth.
214
Liang-fu Zhou
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
volume of cyst liquid ranged from several to scores or more millilitres. There were often some white coloured keratin or cholesterol crystals drifting in the fluid. Microscopically, the walls (capsules) were made up of stratified squamous epithelium attached to fibrous tissue. Proliferated, keratinized and desquamated epithelium formed the central bulk of tumour. Sometimes leakage of the contents had led to irritation in the adjacent tissue, resulting in inflammation and granulation. Thus the arachnoid membrane in contact with the tumour often became thick, fibrous and hyalinized, sometimes with infiltration of lymphocytes, histocytes and giant cells. Haemorrhage, necrosis and haemosiderosis or giant cells phagocytizing haemosiderin in the cyst capsules were found in nine cases.
The operative treatment The patients can be divided into two groups: group A (58 patients), patients treated, mostly before 1981, without microsurgical technique; group B (44 patients), patients treated with operative microscope or loupe. Total removal of tumour was achieved in 17 (29.3%) and 32 (72.7%) respectively in groups A and B. Subtotal removal (with only a small piece of capsule left) was achieved in 8 cases in group A and 6 cases in group B; major removal (removal of the tumour contents and a part of capsule) in 26 cases in group A and 6 cases in group B; partial removal (with part of tumour
content and large portion of capsule left) in 4 in group A and none in group B; a shunting procedure was performed in only one case and it was not stated whether or not a shunting proceedure was performed in two cases in group A. Five patients in group A died after operation. The surgical mortality rates were 4.9% overall and 8.6% in group A. Causes of death were as follows: purulent meningitis resulting from CSF leakage (2), intracranial haematoma ( l ) , acute hepatitis (l), and pneumonia (1). Of the remaining 97 patients, 20 (20.6%) suffered from aseptic meningitis with a fever lasting 1-3 weeks. Sixty-eight patients (70.1%) underwent a follow-up study with a time range from 1-37 years (mean 13 years). The results are shown in Table 111. Four patients experienced recurrence of tumour verified by CT at 20 years (1 case), 12 years ( 1 case), 8 years (1 case) and 5 years (1 case) from the initial surgery to appearance of recurring symptoms. All but one underwent second operations with excellent or good results. In the follow-up study prognosis was evaluated as follows: excellent (full recovery to normal activities without or with mild neurological deficits); good (able to take care or him or herself at home with moderate neurological deficits); poor (dependent on help with severe neurological deficits); and dead.
Discussion
Based on the pathogenesis, intracranial epidermoid tumours can be divided into two categorie~:~.~ TABLE 111. Results of follow-up study Congenital inclusion epidermoid t u mour. The tumour results from incluSurgical procedure *N E G P D sion of squamous epithelial remnants in the neural tube when the neural tube Total removal 44 41 3 (stroke) Subtotal removal 8 5 3 separates from the ectoderm between Large removal 15 11 4** the third and fifth weeks of embryonic Partial removal 1 1 life. Total 68 57 4 7 Acquired implantation epidermoid tumour. The origin is ectopic skin ele*N, Number of cases; E, excellent; G, good; P, poor; D, ments which are brought into the crandeath. ium by some trauma, puncture or surgi**Head trauma in 1 case, stroke in 1 case, tumour recurrence in 1 case, metastatic lung cancer in 1 case. cal operation.
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid turnours, diagnosis and treatment In the present paper, all our patients' tumours were of congenital origin, and they constituted 1 . 1 % of all intracranial tumours and 13.5% of all congenital neoplasms seen in our Institute. The ages at onset of symptoms were between 20 and 50 years. Most of the tumours were located in the subarachnoid space or cisterns and the duration of symptoms was often over three years. All of these data are similar to those reported in the literature.'q3 Generally epidermoid tumour is a benign neoplasm growing so slowly and extending along vascular trees, cranial nerves and brainstem that it does not shift or compress these structures, nor does it block the CSF circula.~ to tion at an early stage of d i ~ e a s eAccording the anatomical location, the clinical manifestations can be divided into several syndromes,' but the tumour often extends along the base of the brain, growing from supratentorial to infratentorial region or vice versa without specific localizing symptoms. We believe that syndromes only indicate the location of the major part of the tumour and do not represent its extent. Trigeminal neuralgia was once considered a common symptom of the epidermoid tumour of C P angle, especially in young persons, but it only occurred in onethird of cases in our series and 10-20% of cases reported in the literat~re.'-~ Therefore it is difficult to identify the nature and extent of the tumour only from the clinical manifestations.1° In the pre-CT era, the main diagnostic means for epidermoid tumour were pneumoencephalography, ventriculography and angiography, which shared an SO-90% of diagnostic rate, but they were only for rather large tumours and merely showed signs of an intracranial space-occupying lesion. On the contrary, C T and MRI have the advantages of speed of diagnosis and convenience and are almost painless. C T can reveal the special features of epidermoid tumours by which a diagnosis can be made." Typically, epidermoid tumour absorption values are low, ranging from -22 to 32 HU, and do not increase following intravenous injection of contrast material. These characteristic features are
21 5
attributed to the admixture of keratinized desquamated epithelium and cholesterol with a thin and avascular wall. A small calcified area of high density can sometimes be found within or around the tumour. Some epidermoid tumours may have a non-enhancing dense image (measuring 80-120 HU) with a low-density nodule; this was found in four cases in this series. The cause of high density may be a haemorrhage or highly concentrated protein within the turnour.'* A few epidermoid tumours may show iso-density or slight high density lesions with increasing density irregularly after injection of contrast. This phenomenon usually indicates a malignant degeneration of the l e ~ i o n . ' ~CJT~ scan, however, has its limits in diagnosis, especially for lesions located in the posterior fossa in which the lesion is often confused with the adjacent bones, so that CT metrizamide cisternography is sometimes needed;15 also, the typical CT appearance of epidermoids is not specific and may be imitated by other cystic lesions. Recently, MRI has been used in our service, and we found that it is helpful in diagnosis and in delineating the extent of an epidermoid tumour, especially as a complement to CT.I6 The primary treatment for epidermoid tumour should be surgical removal. With the aid of microsurgical technique, the likelihood of complete removal of tumour is increasing, rising from 29.3% (before 1981) to 72.7% (after 1981) in this series. As the tumour wall is so thin and adherent to some important structures, it is sometimes difficult to obtain complete removal without increasing neurological deficits. Even then, many patients gain long-term relief. As shown in Table 111, of 24 patients with incomplete removal, 1 died of recurrence, 3 died of other diseases, 3 underwent reoperation with excellent or good results and the remaining 17 patients returned to their normal activities without recurrent manifestations. We believe, therefore, that the contents and the capsule of an epidermoid tumour should be removed as completely as possible, provided that no additional neurological intereference is inflicted.
216
Liang-fu Zhou
Acknowledgements
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Thanks are due to Professor Donald Simpson, Department of Neurosurgery, Adelaide Children’s Hospital, North Adelaide, South Australia, for reading the manuscript and giving valuable advice.
Address for requests for offprints: Liang-fu Zhou, MD, Department of Neurosurgery, Institute of Neurology, S.M.U., 12 Wulumiqi Zhong Road, Shanghai 200040, China.
References 1 Obrador S, Lopoz-Zafra JJ. Clinical features of the
2
3 4 5
epidermoids of the basal cisterns of the brain. J Neurol Neurosurg Psychiat 1969; 32:450-4. Russell DS, Rubinstein LJ. Congenital tumours of maldevelopmental origin. In: Pathology of Tumours of the Nervous System. 4th edn. London: Edward Arnold, 1977; 24-64. Tytus TS, Pennybacker J. Pearly tumours in relation to the nervous system. J Neurol Neurosurg Psychiat 1956; 19:241-59. Gutin PH, et al. Cerebral convexity epidermoid tumour subsequent to multiple percutaneous subdural aspiration. J Neurosurg 1980; 52574. Toglia JU, Netsky MG, Alexander E Jr. Epidermoid tumours of the cranium: their common nature and pathogenesis. J Neurosurg 1965; 23:384-93.
6 Guidetti B, Gagliarti FM. Epidermoid and dermoid cysts: clinical evaluation and late surgical results. J Neurosurg 1977; 47:12-8. 7 Sabin HI, Bordi LT, Symon L. Epidermoid cyst and cholesterol granulomas centred on the posterior fossa. 20 years of diagnosis and management. Neurosurgery 1987; 21~798-805. 8 Yamakawa K, Shitara N, Genka S, Manaka S, Takakura K. Clinical course and surgical prognosis of 33 cases of intracranial epidermoid tumours. Neurosurgery 1989; 24:568-73. 9 Yasargil MG, Abernathy CD, Sarioglu AC. Microsurgical treatment of intracranial dermoid and epidermoid tumours. Neurosurgery 1989; 24:561-7. 10 Rosario M, Becker DH, Conley FK. Epidermoid tumours involving the 4th ventricle. Neurosurgery 1981; 9:9-13. 11 Davis KR, Robinson GH, Taveras JM, New PEJ, Trever R. Diagnosis of epidermoid tumours by CT. Radiology 1976; 119:347-53. 12 Braun IF, Naidich TP, Leeds NE, Koslow M, Zimmerman HM, Chase NE. Dense intracranial epidermoid tumours. Radiology 1977; 122:717-9. 13 Dubois PJ, Sage M, Luther JS, Burger PC, Heinz ER, Drayer BP. Malignant changes in an intracranial epidermoid cyst. J Comput Assist Tomogr 1981; 5433-5. 14 Nosaka Y, Nagao S,Tabuchi K, Nishimoto A. Primary intracranial epidermoid carcinoma. J Neurosurg 1979; 50830-3. 15 Fein JM, Lipow K, Taati F, Lansem T. Epidermoid turnour of the C P angle: Diagnostic value of CT metrizamide tomography. Neurosurgery 1981; 9:179-82. 16 Latack JT, Kartush JM, Kemink JL, Graham MD, Knake JE. Epidermoidomas of the CP angle and temporal bone: C T and MR aspects. Radiology 1985; 157:361-6.
ORIGINAL ARTICLE
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid tumours: thirty-seven years of diagnosis and treatment LIANG-FU ZHOU
Institute of Neurology, Department of Neurosurgery, Shanghai Medical University, Shanghai, People’s Republic of China
Abstract The clinical, operative and pathological characteristics of 102 consecutive cases of intracranial epidermoid tumours are reported. These cases constituted 1.1% of all intracranial turnours and 13.5% of congenital neoplasma admitted to our service in the period 1951-88. Of 91 (89.2%) intradural tumours, 74 (72.5%) were in the subarachnoid cisterns, especially in the cerebellopontine angle cistern (31 cases). The tumours were solid in 69 cases (67.6%) and cystic in 26 (25.5%); the remaining 7 cases were not recorded. There were no specific clinical features with which to identify the nature and extent of the tumour. Diagnosis and treatment are described, with an evaluation of CT and MRI. Before 1981, total removal rate of tumour was 29.3%; after that date it was 72.7% with the aid of microsurgery. The overall surgical mortality rate was 4.9% (5 cases), but there were no deaths in the microsurgical group. Follow-up for a period of 0.5-37 years (mean 13 years) was carried out in 68 patients (70.1%). Among 24 patients with incomplete removal, recurrence of tumour was verified in 4 cases; 3 underwent reoperation with excellent or good results. One patient refused operation and died. All the remaining 20 cases, save 3 who died of other diseases, returned to their normal activities without recurrent manifestations. The results suggest that the primary treatment of epidermoid turnours should be surgical removal including the contents and capsule of a tumour. With the aid of microsurgical technique, complete removal is possible. Patients with incomplete removal can also obtain a long-term favourable result. Key words: Intracranial epidermoid tumour, diagnosis treatment.
66 years, mean 38.6 years. The duration of disease up to the time of admission was from 1 month to 15 years, mean 3.5 years. The lesions in all patients were proved histologically and their locations are shown in Table I.
Introduction Epidermoid tumour is a common congenital tumour, and constitutes approximately 0.2-1 % of all intracranial turn our^.*-*^^ During a period of 37 years, 1951-88, 102 patients were admitted to our Institute for treatment. In the present paper, we summarize our experience in the diagnosis, treatment and long-term followup, with a review of the relevant literature.
Symptoms and signs The clinical manifestations in 102 patients are set out in Table 11.
Clinical data Of 102 patients, 64 were males and 38 females, a sex ratio of 1.7:1. Their ages ranged from 7 to
Diagnostic investigations
21 I
Because computed tomography (CT) was not
212
Liang-fu Zhou
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
'TABLE I. T h e location of 102 cases of intracranial epidermoid turnours* (%) Intradural (91 cases)
89.2
Extradural (1 1 cases) anterior cranial fossa (5) middle cranial fossa (5) posterior cranial fossa (1)
10.8
Intraventricular (6 cases) lateral V (1) 3rd V (2) 4th V (3)
5.9
Intracerebral (1 1 cases) supratentorial (4) infratentorial (7)
10.8
Cisternal (74 cases) suprasellar (8) callosal (2) parasello-Sylvian (10) C P angle (3 1 ) parasello-CP angle (8) post-3rd V clivus (9)
72.5
*V, ventricle; CP, cerebello-pontine.
TABLE 11. Clinical manifestations in 102 patients 64 cases Headache or dizziness 8 cases Eye pain 4 cases Anosmia Papilloedema (with or without secondary optic 14 cases atrophy and visual field defect) 2 cases Foster-Kennedy syndrome Proptosis and limitation of extraocular move- 10 cases ment 8 cases Diplopia 16 cases Tic douloureux Trigeminal hypaesthesia 38 cases 12 cases Temporal muscle atrophy IXth-XIIth cranial nerve palsies 24 cases 10 cases Nystagmus 34 cases Ataxia 30 cases Positive pyramidal signs 10 cases Hemiplegia 6 cases Hemidysesthesia 8 cases Disturbances of endocrine function (including sexual inability, amenorrhoea and growth retardation) 12 cases Grand ma1 epilepsy 2 cases Facial pigmentation 1 case Skin neurofibromatosis
used in our Institute until 1980, 51 patients (50%) underwent the following neuroradiological examinations:
Radiology of skull (27 cases). Normal in 11 cases, with signs of intracranial hypertension in 15 cases, dilatation of internal auditory meatus in 1 case. Cerebral angiography (15 cases). Cerebral vessels compressed and shifted with signs of space-occupying lesion were seen in 12 cases. Pneumoencephalography (34 cases) and ventriculography (7 cases). Compression, distortion, shift and obliteration of ventricles or cisterns were noted in 32 and 6 cases respectively. CT (51 cases). In 47 cases, there was a low density lesion with or without calcification around or within the lesion. In the remaining 4, there was a high-density lesion. All of the 51 cases presented no change after enhancement (Figs. 1, 2). I n the past two years, magnetic resonance imaging (MRI) has been used in 6 cases. In all there was a high signal T1- and T 2 image of an extra-axial tumour (Fig. 3). Pathology Macroscopically, all tumours, except seven with insufficient data, can be divided into two groups: Solid tumour (69 cases). These were white in colour, with the lustre of pearls. The walls of the tumours were transparent and fragile. They contained cheesy material made up of desquamated cells and keratin with a small amount of white liquid. Cystic tumour (26 cases). T h e capsules were smooth and transparent, the colour varied with the contents which were white in 2 cases, butter-yellow in 6 cases, brown in 10 cases and ink-green in 8 cases. T h e contents varied from watery to thick material like tar, which quickly coagulated into an agar-like substance when exposed to air. T h e
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid tumours, diagnosis and treatment
2 13
FIG. 1. Pre- (left) and postenhanced (right) C T scans, showing typical unenhanced hypodense lesion of posterior 3rd ventricle.
FIG. 2. Pre- (left) and postoperative (right) C T scans of a non-enhancing hyperdense lesion of posterior 3rd ventricle.
FIG. 3. T1- (left) and T2-image (right) of MRI showing a high signal clival epidermoid with symmetrical growth.
214
Liang-fu Zhou
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
volume of cyst liquid ranged from several to scores or more millilitres. There were often some white coloured keratin or cholesterol crystals drifting in the fluid. Microscopically, the walls (capsules) were made up of stratified squamous epithelium attached to fibrous tissue. Proliferated, keratinized and desquamated epithelium formed the central bulk of tumour. Sometimes leakage of the contents had led to irritation in the adjacent tissue, resulting in inflammation and granulation. Thus the arachnoid membrane in contact with the tumour often became thick, fibrous and hyalinized, sometimes with infiltration of lymphocytes, histocytes and giant cells. Haemorrhage, necrosis and haemosiderosis or giant cells phagocytizing haemosiderin in the cyst capsules were found in nine cases.
The operative treatment The patients can be divided into two groups: group A (58 patients), patients treated, mostly before 1981, without microsurgical technique; group B (44 patients), patients treated with operative microscope or loupe. Total removal of tumour was achieved in 17 (29.3%) and 32 (72.7%) respectively in groups A and B. Subtotal removal (with only a small piece of capsule left) was achieved in 8 cases in group A and 6 cases in group B; major removal (removal of the tumour contents and a part of capsule) in 26 cases in group A and 6 cases in group B; partial removal (with part of tumour
content and large portion of capsule left) in 4 in group A and none in group B; a shunting procedure was performed in only one case and it was not stated whether or not a shunting proceedure was performed in two cases in group A. Five patients in group A died after operation. The surgical mortality rates were 4.9% overall and 8.6% in group A. Causes of death were as follows: purulent meningitis resulting from CSF leakage (2), intracranial haematoma ( l ) , acute hepatitis (l), and pneumonia (1). Of the remaining 97 patients, 20 (20.6%) suffered from aseptic meningitis with a fever lasting 1-3 weeks. Sixty-eight patients (70.1%) underwent a follow-up study with a time range from 1-37 years (mean 13 years). The results are shown in Table 111. Four patients experienced recurrence of tumour verified by CT at 20 years (1 case), 12 years ( 1 case), 8 years (1 case) and 5 years (1 case) from the initial surgery to appearance of recurring symptoms. All but one underwent second operations with excellent or good results. In the follow-up study prognosis was evaluated as follows: excellent (full recovery to normal activities without or with mild neurological deficits); good (able to take care or him or herself at home with moderate neurological deficits); poor (dependent on help with severe neurological deficits); and dead.
Discussion
Based on the pathogenesis, intracranial epidermoid tumours can be divided into two categorie~:~.~ TABLE 111. Results of follow-up study Congenital inclusion epidermoid t u mour. The tumour results from incluSurgical procedure *N E G P D sion of squamous epithelial remnants in the neural tube when the neural tube Total removal 44 41 3 (stroke) Subtotal removal 8 5 3 separates from the ectoderm between Large removal 15 11 4** the third and fifth weeks of embryonic Partial removal 1 1 life. Total 68 57 4 7 Acquired implantation epidermoid tumour. The origin is ectopic skin ele*N, Number of cases; E, excellent; G, good; P, poor; D, ments which are brought into the crandeath. ium by some trauma, puncture or surgi**Head trauma in 1 case, stroke in 1 case, tumour recurrence in 1 case, metastatic lung cancer in 1 case. cal operation.
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Intracranial epidermoid turnours, diagnosis and treatment In the present paper, all our patients' tumours were of congenital origin, and they constituted 1 . 1 % of all intracranial tumours and 13.5% of all congenital neoplasms seen in our Institute. The ages at onset of symptoms were between 20 and 50 years. Most of the tumours were located in the subarachnoid space or cisterns and the duration of symptoms was often over three years. All of these data are similar to those reported in the literature.'q3 Generally epidermoid tumour is a benign neoplasm growing so slowly and extending along vascular trees, cranial nerves and brainstem that it does not shift or compress these structures, nor does it block the CSF circula.~ to tion at an early stage of d i ~ e a s eAccording the anatomical location, the clinical manifestations can be divided into several syndromes,' but the tumour often extends along the base of the brain, growing from supratentorial to infratentorial region or vice versa without specific localizing symptoms. We believe that syndromes only indicate the location of the major part of the tumour and do not represent its extent. Trigeminal neuralgia was once considered a common symptom of the epidermoid tumour of C P angle, especially in young persons, but it only occurred in onethird of cases in our series and 10-20% of cases reported in the literat~re.'-~ Therefore it is difficult to identify the nature and extent of the tumour only from the clinical manifestations.1° In the pre-CT era, the main diagnostic means for epidermoid tumour were pneumoencephalography, ventriculography and angiography, which shared an SO-90% of diagnostic rate, but they were only for rather large tumours and merely showed signs of an intracranial space-occupying lesion. On the contrary, C T and MRI have the advantages of speed of diagnosis and convenience and are almost painless. C T can reveal the special features of epidermoid tumours by which a diagnosis can be made." Typically, epidermoid tumour absorption values are low, ranging from -22 to 32 HU, and do not increase following intravenous injection of contrast material. These characteristic features are
21 5
attributed to the admixture of keratinized desquamated epithelium and cholesterol with a thin and avascular wall. A small calcified area of high density can sometimes be found within or around the tumour. Some epidermoid tumours may have a non-enhancing dense image (measuring 80-120 HU) with a low-density nodule; this was found in four cases in this series. The cause of high density may be a haemorrhage or highly concentrated protein within the turnour.'* A few epidermoid tumours may show iso-density or slight high density lesions with increasing density irregularly after injection of contrast. This phenomenon usually indicates a malignant degeneration of the l e ~ i o n . ' ~CJT~ scan, however, has its limits in diagnosis, especially for lesions located in the posterior fossa in which the lesion is often confused with the adjacent bones, so that CT metrizamide cisternography is sometimes needed;15 also, the typical CT appearance of epidermoids is not specific and may be imitated by other cystic lesions. Recently, MRI has been used in our service, and we found that it is helpful in diagnosis and in delineating the extent of an epidermoid tumour, especially as a complement to CT.I6 The primary treatment for epidermoid tumour should be surgical removal. With the aid of microsurgical technique, the likelihood of complete removal of tumour is increasing, rising from 29.3% (before 1981) to 72.7% (after 1981) in this series. As the tumour wall is so thin and adherent to some important structures, it is sometimes difficult to obtain complete removal without increasing neurological deficits. Even then, many patients gain long-term relief. As shown in Table 111, of 24 patients with incomplete removal, 1 died of recurrence, 3 died of other diseases, 3 underwent reoperation with excellent or good results and the remaining 17 patients returned to their normal activities without recurrent manifestations. We believe, therefore, that the contents and the capsule of an epidermoid tumour should be removed as completely as possible, provided that no additional neurological intereference is inflicted.
216
Liang-fu Zhou
Acknowledgements
Br J Neurosurg Downloaded from informahealthcare.com by University of Otago on 01/07/15 For personal use only.
Thanks are due to Professor Donald Simpson, Department of Neurosurgery, Adelaide Children’s Hospital, North Adelaide, South Australia, for reading the manuscript and giving valuable advice.
Address for requests for offprints: Liang-fu Zhou, MD, Department of Neurosurgery, Institute of Neurology, S.M.U., 12 Wulumiqi Zhong Road, Shanghai 200040, China.
References 1 Obrador S, Lopoz-Zafra JJ. Clinical features of the
2
3 4 5
epidermoids of the basal cisterns of the brain. J Neurol Neurosurg Psychiat 1969; 32:450-4. Russell DS, Rubinstein LJ. Congenital tumours of maldevelopmental origin. In: Pathology of Tumours of the Nervous System. 4th edn. London: Edward Arnold, 1977; 24-64. Tytus TS, Pennybacker J. Pearly tumours in relation to the nervous system. J Neurol Neurosurg Psychiat 1956; 19:241-59. Gutin PH, et al. Cerebral convexity epidermoid tumour subsequent to multiple percutaneous subdural aspiration. J Neurosurg 1980; 52574. Toglia JU, Netsky MG, Alexander E Jr. Epidermoid tumours of the cranium: their common nature and pathogenesis. J Neurosurg 1965; 23:384-93.
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