MALIGNANT MELANOMA OF THE CEREBELLO-PONTINE
ANGLE REGION
F. MENEZES BRAGA — OSWALDO I. TELLA Jr. — ADELMO FERREIRA CEME F. JORDY
S U M M A R Y — A c a s e o f m a l i g n a n t m e l a n o m a i n t h e c e r e b e l l o - p o n t i n e a n g l e r e g i o n is p r e s e n t e d i n a 72 y e a r s o l d f e m a l e p a t i e n t , w h o h a d n e u r o l o g i c a l e x a m i n a t i o n a n d C T s c a n s u g g e s t i v e o f a c o u s t i c n e u r o m a . T h e s u r g i c a l f i n d i n g a n d t h e h i s t o l o g i c a l e x a m i n a t i o n p r o v i d e d t h e d i a g n o s i s . A s a p r i m a r y f o c u s w a s n o t f o u n d o n c l i n i c a l e x a m i n a t i o n a n d a l t h o u g h a u t o p s y w a s n o t c a r r i e d o u t , t h e r e i s a p o s s i b i l i t y o f t h e d i a g n o s i s b e i n g a p r i m a r y m a l i g n a n t m e l a n o m a i n C N S . T h i s s p e c i f i c l o c a t i o n f o r t h i s k i n d o f t u m o r w a s f o u n d t o b e r a r e w h e n l i t e r a t u r e is l o o k e d u p .
Melanoma maligno da região do ângulo ponto-cerebelar.
R E S U M O — R e g i s t r o d e c a s o d e m e l a n o m a m a l i g n o n a r e g i ã o d o â n g u l o p o n t o - c e r e b e l a r e m p a c i e n t e d o s e x o f e m i n i n o , c o m 72 a n o s d e i d a d e , c o m e x a m e n e u r o l ó g i c o e t o m o g r a f i a c o m p u t a d o r i z a d a s u g e s t i v o s d e n e u r i n o m a d o a c ú s t i c o , e m q u e o d i a g n ó s t i c o f o i e s t a b e l e c i d o p e l o a c h a d o c i r ú r g i c o e p e l o e x a m e h i s t o p a t o l ó g i c o . C o m o n ã o f o i a c h a d o f o c o p r i m á r i o n o e x a m e c l í n i c o e e m b o r a n ã o t e n h a s i d o f e i t a a u t o p s i a , h á p o s s i b i l i d a d e d e q u e o d i a g n ó s t i c o s e j a d e m e l a n o m a m a l i g n o p r i m á r i o n o s i s t e m a n e r v o s o c e n t r a l . E s t a l o c a l i z a ç ã o p a r t i c u l a r d e s s e t i p o d e t u m o r é c o n s i d e r a d a r a r a , l e v a n d o e m c o n t a o s d a d o s d a l i t e r a t u r a .
Malignant melanoma generally occurs in the Caucasian population ( 9 8 % ) , repre-sents about 1% of the neoplasias in general, and is responsable for 1% of deaths due to neoplasias. The greatest incidence occurs between the ages of 3 5 and 50, and after diagnosis one may expect a 5 year life expectancy in 6 7 % of cases 13,41 These tumors present a high degree of metastatization in all organs of the body, mainly in CNS, where they constitute the third commonest cause of metastasis 2,18,31. Patients with skin melanomas may reveal 6 to 1 1 % metastasis in the C N S during evolution, and this percentage may increase up to 9 0 % in autopsies 2,31,43. in the S N C metastasis occurs more frequently in the brain hemispheres 22. The occurrence of primary malignant melanomas in the C N S has been reported to reach the pituitary, pineal gland, choroid plexus, cerebellum, cisterna magna and Sylvian fissure 9,17,21,34, 36,37,39. When primary they arise from melanocytes present in leptomeninges of the brain convexity or at the base, in the posterior fossa, in the spinal cervical canal, the coverings of the pia-mater vessels, the reticular formation of the pons and medulla, substantia nigra and locus coerulleus 21,24,25,45. W e report a case of a large malignant melanoma of the cerebello-pontine angle ( C P A ) with a very similar appearance of acoustic neuroma in the computerized tomography ( C T ) . Although autopsy was not performed it could be a primary melanoma, as no other focus was detected.
C A S E R E P O R T
IG, a 72 years old female patient started having vertigo and progressive deafness
in the right ear about IS months ago. More recently, two months ago, she developed gait
disturbance with tendency to veer to the right side, mental deterioration, and loss of urine
N e u r o s u r g i c a l D e p a r t m e n t , E s c o l a P a u l i s t a d e M e d i c i n a , S ã o P a u l o .
control. C T scan showed a large tumor in the C P A region with characteristics similar to acoustic neuroma ( F i g . 1 ) . There was a shift of the fourth ventricle and important supra-tentorial internal hydrocephalus. T h e internal auditory canal was slightly bigger on that side. Having cardiac insufficency she was submitted to a C S F shunt with local anaestesia. There was improvement of ataxia and of urine control for two months, after which she again starts presenting vertigo, and motor ataxia together with vomiting. On a new C T study the ventricles were small. T h e vomiting became constant, impairing her physical condition, she lost weight and was unable to stand up. I t was decided to perform an inner decompression of the probable neuroma. Tiie hematologic examination, chest X ray, glycemia
Fig. 1 — Case IG. CT scan: hypercap-tant globous tumor with precise limits in the right cerebello-pontine angle.
and urea were normal. After cardiac compensation the patient was operated. I n lateral position a craniectomy of the posterior fossa w a s made. I t was found a big tumor with a dark aspect, thin capsule, extremely bloody, occupying the whole of the cerebello-pontine region, pressing on and deviating the brain stem, extending upward to the Pachioni foramen and downward enclosing the last cranial nerves. I t penetrated into the internal acoustic canal, widening it and enclosing the nerves there. T h e proposed partial removal of the tumor was not possible since bleeding persisted until the whole tumor w a s removed. F o r the surgery a Laser w a s used. T h e last cranial nerves and the trigeminal one were saved but the facial and acoustic were damaged; the tumor was cureted from the internal acoustic canal. The main point of implantation of the tumor w a s in the duramater, a little bit lower than this canal. After surgery the patient had a good evolution till the third day when she developed a pulmonary edema and cardiac infartion, dying in the fifth post operative day. Necropsy was not permitted. W h i l s t still alive she was submitted to a detailed exa-mination of the skin, mouth mucosa, eyes, genitalia and anus, without any positive finding for a primary focus of melanoma. T h e histologic examination showed a tumor composed of pleomorphic cells, with a fusiform aspect, having a b i g and hypercromatic nucleus and an eosinophilic cytoplasm containing pigment granules, some of them grouped around the vascular structures. T h e staining for iron pigments was negative. T h e diagnosis of malignant melanoma was made ( F i g . 2 ) .
C O M M E N T S
498 Arq Neuro-Psiquiat (Sao Paulo) lfi(k) 1989
spinal canal-cord and 3 7 . 2 % were diffuse. Madajewicz et a l .2 8
found in 66 autopsies 50% supratentorials, 4 % infratentorials, 5 % in the meninges and 4 4 % diffuse. In 7 3 % they were multiple, and single in 2 7 % .
As far as the primary melanoma in C N S is concerned, its presence was first described by Wirchow in 1859. This lesion is not frequent, has prolonged duration and rarely gives metastasis or dissemination outside the C N S 10,19,36,38. it is difficult to distinguish a primary lesion from a metastatic one, when single. In order to confirm a case as a primary melanoma one should have a necropsy, which must include an examination of the ocular chamber, not done in the majority of cases 37. These parameters, when followed, help in the differentiation of primary melanoma. A melanoma of the C N S can not be considered as primary when an ocular enucleation has been done, when a lesion has been cauterized or removed from the skin, when a cutaneous melanoma belongs to a region of lymphatic drainage and the skin has been treated, or when the anus and genitalia were not e x a m i n e d1 4
. According to these criteria, the incidence of primary melanoma in the C N S is about 4.4% 12,22. The case we present may be primary as no suspected lesion was found. A detailed examination of the patient was done mainly because we already had a histologic diagnosis. The ideal study would be the necropsy but it was not accepted by the family. W e examined the various chest X rays of the patient and nothing was found related to a tumoral lesion.
Many locations in the C N S have been described for the melanomas: hypophysis, pineal gland, choroid plexus, cisterna magna and Sylvian fissure. In some cases whether or not they are primary or metastatic is questionable 4,9,17,34,37,39. in our case the tumor was located in the CPA, and the similarity to the C T appearence of acoustic neuroma was striking. In an exhaustive research of the literature we found 6 cases described as malignant melanoma located in the C P A1
-6
'8
-1 3
,3 2
-3 3
, in which it was also difficult to distinguish if primary or metastatic, none having lesion outside the C N S . In 4 of these cases autopsies were done 6,8,13,33. One of them cannot be considered as primary as lesion was discovered in the penis, which was subsequently amputated. In one case 1
autopsy was not done and in another33
Generally, the primary melanoma originates in the leptomeninges but it may originate in the paquimeninges as reported by Narayan et al.32. It is important to emphasize the possibility of other pigmented tumors in this region, which brings accurate diagnosis into doubt: pigmented Schwannomas which have been described in the 8th nerve 16, the mandible 23t the spinal canal
7
, in association with meningeal melanosis 6, adamantinoma and von Recklinghausen 29. They are slow growing tumors, that do not metastasize and have good prognosis. Histologically they are formed of fusiform cells with oval nuclei, sometimes arranged in palisade, with melanin present in the cytoplasm and in the extracellular space. These tumors present two distinct types of cells, Schwann cells and melanotic ones 7,16,29,40. Another tumor which can contain pigment is the melanotic meningeoma: 12 cases were described in the
lite-rature up to 1983 26. It is formed by fusiform cells arranged in fascicles with oval nuclei, concentric nucleolus with chromatin and melanin granules present. The histo-logical aspect recalls the fibroblastic meningeoma 27. These may suffer malignant changes with the presence of mitosis, necrosis or hemorrhage, and may show quick growth, an infiltrative character and dissemination 26,27. Another tumor is the pig-mented medulloblastoma, also with two lineages of cells: one small with rounded and hyperchromatic nuclei, scarce cytoplasm and mitosis, and the other, ephitelial cells with pigment grouped around tubular structures, forming a significant part ot the tumor n.20,44. Histologically our case had the typical aspect of malignant mela-noma without any possibility of confusion with the above described tumors. The melanomas frequently produce hemorrhages, that occur as a result of endothelial fenestrations of the capillaries, together with the fragility of the basal layer 46. The hemorrhage may occur in the brain tissue or in the subarachnoid space. About 2 to 6% of the cases of subarachnoid hemorrhage are due to tumors, mainly from mela-noma and the choriocarcimela-noma 3. In the spontaneous intraparenchymatous hemorrhage, without any apparent cause, it is always important to do a biopsy of the surrounding tissue to exclude the possibility of this t u m o r4 2
. The meningeal melanosis may also cause CSF blockage 24.
W h e n present in the CPA, malignant melanoma damages the nervous structures, mainly the 8th nerve, as occurred with our patient and in the cases described in the literature. T h e presence of intracranial hypertension due to brain-stem compression or CSF blockage is common as well. In our case the intracranial hypertension was not evident and clinical signs suggested the normal pressure hydrocephalus syndrome, that improved after CSF shunt. Despite a C T scan having shown normal ventricles two months later, the patient got worse and this impairment was interpreted as being due to brain stem distortion by the tumor and then a posterior fossa exploration was performed despite her precarious clinical condition. There are no rigid criteria
for surgery in cases of malignant melanoma of the C N S . A patient with one lesion in an accessible area should be submitted to surgical treatment, although having a short life expectancy so. Madajewicz et al.28 in 125 cases of brain melanomas, reported only 3 weeks survival in patients untreated, 6 weeks when receiving corticotherapy, 9 weeks when receiving radiotherapy, 11 weeks when treated with chemotherapy,
and 25 weeks when surgery was carried out for a single metastasis 18.28.
T o d a y in the treatment of malignant melanomas, corticotherapy, chemotherapy, immunotherapy, radiotherapy and surgery are used 28. In our particular case death occurred after surgery and no other kind of treatment could be initiated.
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