Pediatr Radiol (1995) 25:540-543

Pediatric Radiology 9 Springer-Verlag 1995

Desmoplastic infantile ganglioglioma: CT and MRI features O. R. Tenreiro-Picon I, S.V. Kamath I, J.R. Knorr I, R. L. Ragland I, T.W. Smith 2, K.Y. Lau I 1 Department of Radiology, University of Massachusetts Medical Center, 55 Lake Avenue North, Worcester, MA 01655, USA 2 Department of Neuropathology, University of Massachusetts Medical Center, 55 Lake Avenue North, Worcester, MA 01655, USA Received: 2 August 1994/Accepted: 8 December 1994

Abstract. W e p r e s e n t t h r e e cases of d e s m o p l a s t i c inf a n t i l e g a n g l i o g l i o m a in p a t i e n t s a d m i t t e d to o u r institut i o n in t h e p a s t 8 years. C T a n d M R findings a r e discussed. Typically, t h e s e lesions a r e l o c a t e d in t h e f r o n t a l a n d p a r i e t a l lobes, a p p e a r i n g as cystic t u m o r s w i t h a solid c o r t i c a l c o m p o n e n t w i t h i n t h e c e r e b r u m , w h i c h enh a n c e s intensely, a n d m o d e r a t e s u r r o u n d i n g e d e m a .

G a n g l i o g l i o m a is a r a r e p r i m a r y t u m o r t h a t a c c o u n t s for 0.5-1.0 % of all i n t r a c r a n i a l t u m o r s [1, 2]. T h e s e g e n e r ally a r e l o w - g r a d e n e o p l a s m s w h i c h a r e b e n i g n a n d h a v e a good prognosis. Desmoplastic infantile ganglioglioma (DIG) represents a distinctly uncommon clinicopathol o g i c a l e n t i t y o f cystic b r a i n t u m o r s w h i c h u s u a l l y arise in s u b j e c t s b e l o w t h e a g e of 18 m o n t h s [3]. W e d e s c r i b e t h e C T a n d M R f e a t u r e s of t h r e e cases of D I G .

growth and development had been normal. On neurological examination, the patient had mild weakness on the left side involving the upper and lower extremities. A C T scan of the head was done (GE 9800); 5-mm axial sections were obtained with and without contrast, revealing a cystic mass in the right temporoparietal lobe with an anteromedial isodense component which was enhanced intensely after contrast. Also seen was vasogenic edema and mass effect surrounding the lesion (Fig. 2 a, b). MRI of the brain was done (1.5 T Signa GE) with Tl-weighted (TR 550/TE 11) axial, coronal, and sagittal images with and without Gd DTPA; proton-density (PD) and T2-weighted (TR 2800/ TE 130) images were also obtained. These images revealed a right temporoparietal cystic mass lesion with an intensely enhancing anteromedial component with surrounding vasogenic edema, mass effect, and minimal subfalcine shift to the left (Fig. 3 a, b). After excision of the tumor, the patient showed significant recovery.

Case 3

Case reports Case 1 A previously healthy 4-month-old female with no significant past medical history was admitted after her head circumference had been progressively increasing for 1 month. On physical examination she was afebrile with stable vital signs. Her head circumference was 46 cm with prominent right frontal cranium. A C T scan of the head revealed a large cyst occupying the entire right frontal lobe, with a hyperdense solid component lateral to the cyst at the level of the cortex (Fig. 1). Two days after admission, surgery was undertaken, and during the procedure a large cystic mass was found with a solid tumor on the surface of the brain near the adherent portion of the dura where the lesion was firmly attached. Complete resection of the tumor was not possible.

Case 2 A 5-month-old male infant was admitted with recent onset of generalized seizures. There was no significant prior medical history;

Correspondence to: O.R. Tenreiro-Picon

An 11-month-old boy presented after 14 days of progressive right hemiparesis, which was most marked in the right upper extremity; there was facial paresis as well. His medical history was negative. Physical examination revealed some decreased movement of the right upper and lower extremities. A C T scan of the head without contrast demonstrated a large cystic lesion in the left frontal lobe (Fig.4). MRI of the brain was performed (GE 1.5 T Signa); Tl-weighted axial, coronal without and with Gd-DTPA, as well as PD and T2-weighted images were obtained. These images demonstrated a predominantly cystic mass with an enhancing solid component displacing the cortex in the premotor region. No significant surrounding edema was identified (Fig. 5 a, b). The patient underwent surgery with complete resection of the mass, and there were no complications.

Pathologic findings T h e h i s t o l o g i c f e a t u r e s of all t h r e e t u m o r s w e r e strikingly similar. A l l t h r e e w e r e c e l l u l a r s p i n d l e cell n e o plasms that primarily occupied the subarachnoid space and focally extended into the subjacent brain paten-

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Fig. 1. CT scan without contrast at the level of the lateral ventricles shows a large cystic mass on the right with a hyperdense, rounded superficial component (arrow) Fig.2. a CT scan without contrast shows a cystic mass (arrowheads) in the right temporal lobe (with extension superiorly in the parietal lobe, not seen on these images) with a solid isodense component anteromedially (arrow),surrounding vasogenic edema, and mass effect, b On contrast administration, the solid isodense component (arrow)is enhanced markedly Fig.3. a MR T2-weighted image (TR 2800/TE 130) shows the cystic mass (arrowheads)with the isointense solid component anteriomedially (arrow). b The previously isointense soft tissue component intensely enhances with Gd-DTPA (arrows) Fig.4. CT scan without contrast at the level of the left centrum semiovale shows a cystic lesion in the frontal lobe with smaller cystic areas laterally

c h y m a along the Virchow-Robins spaces. The predominant cells within each t u m o r had oval to elongated, m o d e r a t e l y p l e o m o r p h i c nuclei with elongated processes interspersed a m o n g collagen and reticulin fibers (Fig.6a). Also present were t u m o r cells having m o r e

abundant eosinophilic cytoplasm and eccentric nuclei resembling hypertrophic astrocytes (Fig. 6 a), as well as clusters of larger cells resembling neurons with large eccentric nuclei, p r o m i n e n t nucleoli, and cytoplasm containing Nissl bodies (Fig.6b). Ganglion cells were frequently observed in cases 1 and 3 but were relatively sparse in case 2. The t u m o r in case 1 also contained aggregates of small undifferentiated cells with round hyp e r c h r o m a t i c nuclei. Mitoses were infrequent and necrosis was not observed. In all three cases, immunocytochemical staining for glial fibrillary acidic protein ( G F A P ) d e m o n s t r a t e d n u m e r o u s GFAP-positive astrocytes throughout all regions of the tumor, and i m m u n o staining for synaptophysin or neurofilament protein confirmed the presence of neuronal differentiation. Astrocytic and neuronal differentiation was also confirmed by electron microscopy in cases 2 and 3. I m m u n o c y t o c h e m i c a l staining for the cell proliferation m a r k e r Ki-67 p e r f o r m e d in case 3 revealed a very low labeling index of < 0.5 %.

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Fig.5a, b. Sagittal (a) and coronal (b) T 1-MR scans showing the cystic mass with greatly enhanced solid component after i.v. Gd-DTPA (arrows)

Fig.6. a Photomicrograph showing cellular spindle cell tumor with desmoplastic stroma. A large astrocyte is present in the center of the field (arrow). Hematoxylineosin, original magnification • 180. b Some regions of the tumor have clusters of large neurons with eccentric nuclei and prominent nucleoli and abundant cytoplasm containing Nissl bodies (arrows). The ganglion cells are separated by a fibrillary stroma comprised of astrocytes, collagen, and reticulin fibrils. Hematoxylin-eosin, original magnification x 180

543 Discussion In 1984, Taratuto et al. [8] reported six cases of "superficial cerebral astrocytoma" attached to the dura and involving the cortex in infants under 1 year of age. Three years later, Vandenberg et al. [3] described a rare primary tumor with the same microscopic appearance which was called desmoplastic infantile ganglioglioma, emphasizing the clinicopathological features. Typically, it is a neuroepithelial tumor characterized by voluminous size, intense desmoplasia with a cystic component, and astrocytic/ganglionic differentiation. The tumor usually presents prior to 18 months of age. However, cases have been reported in adolescents and young adults [4]. Males are affected more commonly than females. Seizure is the common mode of presentation. However, frequently there is associated rapid head growth. The D I G usually involves the parietal or frontal lobes [3, 6]. The tumors are large, having two distinct components: There is a cystic area which is an integral part of the tumor and a solid component representing the desmoplastic reaction located adjacent to the meninges and attached to the dura [5-8]. In all of our cases, the tumor had a massive cyst subjacent to a solid, markedly enhancing, superficially located component. On CT scan, a cystic lesion was seen in the parietal and frontal lobes with in iso- or hyperdense solid component, which was intensely enhanced after contrast administration. M R I showed a cystic component which was evidenced by long relaxation times on T1- and T2weighted images, The solid component usually has a short relaxation T1 and it is enhanced strongly after Gd-DTPA. The solid component seen on CT and M R I represents the portion of tumor with varying amounts of intermixed desmoplasia. Vasogenic edema may be seen on imaging but is commonly moderate [9, 10]. In the infantile age-group, one should consider typical gangliogliomas, supratentorial ependymomas, primitive neuroectodermal tumor (PNET), and cerebral astrocytomas in the differential diagnosis. Other tumors which might also be considered are malignant teratomas and sarcomas, which have a higher incidence in infancy than in later childhood. These lesions will not have the D I G appearance. Ependymomas enhance heterogeneously and frequently are calcified. PNETs are usually associated with partial cyst formation, hemorrhages, and areas of necrosis with prominent surrounding edema and have a poor prognosis. Conversely, most authors believe that D I G is a benign neoplasm, although there are contentions that it may be of a dysplastic nature [11, 12]. D I G is distinctly different from the classical ganglioglioma. These differences include the presentation in infancy, the inclusion of immature neuroepithelial cells, the presence of dense desmoplasia, and the pre-

dominant location in the parietal or frontal lobe. Recently, Duffner et al. emphasized the frequent misinterpretation of DIGs as high-grade malignant lesions because of the mitotic activity and focal high cellularity. They suggest that the pathologist should be aware of the characteristics of these lesions, including patient's age and the tumor's cystic appearance [13]. In conclusion, typical imaging features suggesting D I G in infants are: (a) tumor with a large cystic and small cortical solid component which is enhanced by contrast medium intensely; (b) location in the frontal and parietal lobes; (c) apposition to a meningeal surface; and/or (d) contrast enhancement along the meningeal side of the mass.

Acknowledgements. We wish to thank Kathy R. Delongchamp for her help in the preparation of this manuscript.

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