MALIGNIZATION OF A N ARACHNOID CYST
S. L. ROSSITTI * — R. J. BALBO **
S U M M A R Y — A c a s e o f e v o l v e m e n t o f f i b r o s a r c o m a f r o m a s u p r a t e n t o r i a l a r a c h n o i d c y s t ( v e r i f i e d in s u r g e r y f i v e y e a r s b e f o r e ) i s p r e s e n t e d , w i t h b r i e f c o m m e n t s o n t h e e m b r y o n i c o r i g i n o f t h e t i s s u e s i n v o l v e d .
Malignização de um cisto aracnóideo.
R E S U M O — C i s t o s a r a c n ó i d e o s r e p r e s e n t a m d i s p l a s i a m e s o d é r m i c a f o c a l ( d o n e u r o t é l i o s u b d u - ¬ r a l ) , s e n d o s u a a p r e s e n t a ç ã o c l í n i c a d e c o r r e n t e d e s e u t a m a n h o e l o c a l i z a ç ã o . N o p r e s e n t e c a s o , u m f i b r o s s a r c o m a o r i g i n o u - s e d e c i s t o a r a c n ó i d e o s u p r a t e n t o r i a l v e r i f i c a d o e m c i r u r g i a c i n c o a n o s a n t e s . A m a l i g n i z a ç ã o d e c i s t o s a r a c n ó i d e o s d e v e s e r m u i t o r a r a , e e s s e é p r o -v a -v e l m e n t e o p r i m e i r o c a s o r e l a t a d o n a l i t e r a t u r a .
Cancer has been occasionally reported to evolve from congenital malformations. In the present case, a fibrosarcoma arised from an arachnoid cyst of the right sylvian fissure verified in surgery five years before.
C A S E R E P O R T
A C F , a 1 - y e a r - o l d Caucasian m a l e , a d m i t t e d t o t h e N e u r o s u r g i c a l C l i n i c f o u r d a y s a f t e r a h e a d i n j u r y o f m o d e r a t e i n t e n s i t y ( h e f e l l f r o m h i s b e d ) . S i n c e t h i s a c c i d e n t h e r e f u s e d t o eat, h a d f r e q u e n t v o m i t s , a n d s l e p t m o s t o f t h e t i m e . O n e x a m i n a t i o n h e p r e s e n t e d w i t h d r o w s i n e s s , a s y m m e t r i c m a c r o c e p h a l y a n d b i l a t e r a l c h o k e d d i s k s . T h e r e w a s n o m o t o r p a r a l y s i s , r e f l e x a s y m m e t r y o r p a t h o l o g i c a l r e f l e x e s . T h e e n l a r g e m e n t o f h i s h e a d w a s p r o g r e s s i v e s i n c e b i r t h . H e w a s n o t w e l l f e d , a n d p r e s e n t e d a d e l a y e d p s y c h o m o t o r d e v e -l o p m e n t . C r a n i a -l r o e n t g e n o g r a m s h o w e d a -l i n e a r p a r i e t o c c i p i t a -l s k u -l -l f r a c t u r e , e n -l a r g e m e n t of t h e r i g h t t e m p o r a l f o s s a a n d d i s j u n c t i o n o f s u t u r e s . P n e u m o e n c e p h a l o g r a m a n d r i g h t c a r o t i d a n g i o g r a m s h o w e d a f r o n t o t e m p o r a l a v a s c u l a r m a s s l e s i o n . A l a r g e f r o n t o t e m p o r a l c r a n i o t o m y w a s p e r f o r m e d a n d r e v e a l e d a c y s t i c l e s i o n ( F i g . 1) w h i c h s p l a y e d t h e f r o n t a l a n d t e m p o r a l o p e r c u l a e , e x p o s i n g t h e i s l a n d o f R e i l . T h e c y s t w a s f i l l e d w i t h a b o u t ICO m l of c l e a r , s l i g h t l y x a n t h o c h r o m i c f l u i d , w h i c h w a s d r a i n e d . T h e o u t e r c y s t i c w a l l w a s r e s e c t e d a n d i t s c a v i t y c o m m u n i c a t e d w i t h t h e r i g h t l a t e r a l v e n t r i c l e b y m e a n s o f t w o s m a l l p l a s t i c t u b e s . M i c r o s c o p i c e x a m i n a t i o n o f t h e c y s t w a l l r e v e a l e d a d e l i c a t e f i b r o v a s c u l a r m e m b r a n e w i t h an i n t e r n a l l i n i n g o f f l a t t e n e d c e l l s , a n d s p a r s e n e s t s o f m e n i n g o t h e l i a l c e l l s . T h e d i a g n o s i s w a s s y m p t o m a t i c ( h y p e r t e n s i v e ) a r a c h n o i d c y s t , o f d e v e l o p m e n t a l o r i g i n .
H e m a d e a s l o w r e c o v e r y , w i t h g r a d u a l c e s s a t i o n o f p r e s s u r e s y m p t o m s , a n d w a s d i s c h a r g e d a f t e r 4 w e e k s . A p n e u m o e n c e p h a l o g r a m p e r f o r m e d 6 m o n t h s l a t e r s h o w e d a c o m m u n i c a t i n g c y s t i c c a v i t y w i t h n o m a s s e f f e c t . W i t h e x c e p t i o n o f a p e r s i s t e n t m a c r o -c e p h a l y , a n d o n e e p i s o d y o f m e a s l e s m e n i n g i t i s , he r e m a i n e d free f r o m s y m p t o m s f o r 5
T r a b a l h o d o D e p a r t a m e n t o d e N e u r o - P s i q u i a t r i a d a F a c u l d a d e d e C i ê n c i a s M é d i c a s d a P o n t i f í c i a U n i v e r s i d a d e C a t ó l i c a de C a m p i n a s ( P U C C A M P ) e d o D e p a r t a m e n t o d e N e u r o l o g i a e N e u r o c i r u r g i a d o H o s p i t a l V e r a C r u z e H o s p i t a l M u n i c i p a l D r . M a r i o Gatti, C a m p i n a s : * M é d i c o R e s i d e n t e ; ** P r o f e s s o r A d j u n t o .
Malignisation of arachnoid cyst 81
Fig. 1 — Case ACF. Arachnoid cyst of the right sylvian fissure as revealed in surgery.
y e a r s , w h e n h e w a s r e a d m i t t e d w i t h b a c t e r i a l m e n i n g i t i s . H e r e c e i v e d a n t i b i o t i c t h e r a p y a n d w a s d i s c h a r g e d a s y m p t o m a t i c .
H e r e t u r n e d 6 m o n t h s l a t e r p r e s e n t i n g m a r k e d d r o w s ' . n e s s , v o m i t s a n d g a i t i n s t a b i l i t y o f t w o w e e k s d u r a t i o n . O n e x a m i n a t i o n h e p r e s e n t e d left h e m i p a r e s i s a n d b i l a t e r a l c h o k e d d i s k s . R i g h t c a r o t i d a n g i o g r a m d e m o n s t r a t e d a n a v a s c u l a r f r o n t o t e m p o r a l m a s s l e s i o n , w i t h s u b f a c i a l h e r n i a t i o n t o t h e left. A r i g h t f r o n t o t e m p o r a l c r a n i o t o m y d i s c l o s e d m u l t i p l e p e a r l y w h i t e t i s s u e m a s s e s a d h e r e n t t o t h e c y s t w a l l , w i t h a r e a s o f p u l p y c o n s i s t e n c y e a s i l y a s p i r a b l e ; the r e m n a n t o f t h e c y s t i c c a v i t y w a s f i l l e d w i t h a b o u t 60 m l o f v i s c o u s , b r o w n f l u i d , w h i c h c o a g u l a t e d after d r a i n a g e . T u m o r b i o p s y w a s p e r f o r m e d . M i c r o s c o p i c e x a m i n a t i o n p r o v e d t h e l e s i o n t o b e a f i b r o s a r c o m a , g r a d e I I I ( F i g . 2 ) . A c o m p u t e r i z e d t o m o g r a p h i c s c a n w a s p e r f o r m e d ( F i g . 3 ) , a n d t h e p a t i e n t w a s r e o p e r a t e d . A r a d i c a l e x c i s i o n o f t h e t u m o u r w a s a t t e m p t e d , e x p o s i n g n o r m a l c o r t e x b e n e a t h it. T h e i m m e d i a t e p o s t - o p e r a t i v e r e c o v e r y w a s u n e v e n t f u l , t h e p a t i e n t b e i n g c o n s c i o u s a n d w i t h s l i g h t left h e m i p a r e s i s in t h e d a y f o l l o w i n g t h e s e c o n d o p e r a t i o n . H e d i e d t w o m o n t h s later o f b r o n c h o p n e u m o n i a , n o t h a v i n g i n i t i a t e d r a d i o t h e r a p y . N o e x t r a c r a n i a l m e t a s t a s i s w a s s u s p e c t e d o n c l i n i c a l g r o u n d . N e c r o p s y w a s n o t p e r m i t t e d b y t h e f a m i l y .
C O M M E N T S
The arachnoid is the last of the meninges to differentiate, developing from the inner aspect of the duramaetr. It is of mesodermal origin, avascular, composed of both collagen and modified fibroblasts (arachnoid cells)5. Arachnoid cysts represent a focal reduplication of the normal arachnoid membrane originating a fluid-containing space within the subarachnoid space 5,8. Except when localized in the cerebral
suggest that they are derived from the outer arachnoid cell layer (subdural neuro-thelium), their formation and gradual enlargement being attributable to secretory capacity of the subdural neurothelium 3.
The clinical presentation of arachnoid cysts is usually related to their size. Small cysts are found incidentally in autopsy or C T scans; larger ones behave as space-occupying lesions. In some cases progressive symptoms arise in consequence of head trauma. In recent years, technology has provided an optimization in the diagnosis of intracranial arachnoid cysts. Several observations have pointed to the association with genetic disorders of the mesodermal tissues (Marfan syndrome 9.10, neurofibromatosis n , and autosomal-dominant polycystic kidney d i s e a s e s u g g e s t i n g a common pathogenesis. The incidental finding of an arachnoid cyst in patients with primary intracranial neoplasms (meningeoma 6 and pituitary adenoma 7 ) has also moti-vated some communications.
Fibrosarcomas are common to all organs. In the central nervous system they may arise from preexisting fibroblasts or undifferentiated mesenchymal cells in the duramater, leptomeninges and perivascular connective t i s s u e4
. Occasionally, fibro-sarcomas have followed radiation therapy. Teratogenesis and carcinogenesis are both related to reproductive capacity of somatic cells, and neoplasms have been reported to evolve from congenital malformations2
The evolvement of malignancy from an arachnoid cyst must be very rare. This is probably the first case reported in literature.
R E F E R E N C E S
1. A l l e n A , W i e g m a n T B , M a c D o u g a l l M L — A r a c h n o i d c y s t in a p a t i e n t with a u t o s o m a l - ¬ - d o m i n a n t p o l y c y s t i c k i d n e y d i s e a s e . A m J K i d n e y D i s 8:128, .1986.
2. D i P a o l o J A , K o t i n P — T e r a t o g e n e s i s - o n c o g e n e s i s : a s t u d y o f p o s s i b l e r e l a t i o n s h i p s . A r c h P a t h o l 8 1 : 3 , 1966.
3. G o K G , H o u t h o f f H J , B l a a u w E H , S t o k r o o s 1, B l a a u w G — M o r p h o l o g y a n d o r i g i n o f a r a c h n o i d c y s t s : s c a n n i n g a n d e l e c t r o n m i c r o s c o p y o f t h r e e c a s e s . A c t a N e u r o p a t h o l ( B e r l i n ) 44:57, 1978.
4. K e r n o h a n J W , U i h l e i n A — S a r c o m a s o f t h e B r a i n . C h a r l e s C. T h o m a s , S p r i n g f i e l d , 1962, p g 30.
5. L e m i r e R J , L o e s e r J D , L e e c h R W , A l v o r d E C J r — N o r m a l a n d A b n o r m a l D e v e l o p m e n t o f t h e H u m a n N e r v o u s S y s t e m . H a r p e r & R o w , H a g e r s t o w n , 1975, p g 280.
6. L e p u s c h ü t z H , S a g e r W D , S c h r ö t t n e r O — D o p p e l m e n i n g e o m e m i t A r a c h n o i d a l z y s t e : e i n e s e l t e n e K o m b i n a t i o n . C o m p u t e r t o m o g r a p h i e ( S t t u t g a r t ) 1:33, 1981.
7. R a h i m i z a d e h A , K a g h a z c h i M , H a d d a d i a n K — C o i n c i d e n c e o f an a r a c h n o i d c y s t o f t h e m i d d l e f o s s a a n d a p i t u i t a r y a d e n o m a . N e u r o s u r g e r y 21:261, 1987.
8. R e n g a c h a r y S S , W a t a n a b e I — U l t r a s t r u c t u r e a n d p a t h o g e n e s i s o f i n t r a c r a n i a l a r a c h n o i d c y s t s . J N e u r o p a t h E x p N e u r o l 40 :61, 1981.
9. R o b i n s o r ; R G — T h e t e m p o r a l l o b e a g e n e s i s s y n d r o m e . B r a i n 87:87, 1964.
