|Contributed by C Sarkar, MC Sharma, R Arora, S Gaikwad*, VS Mehta**|
|Departments of Pathology, Neuroradiology* and Neurosurgery**, All India Institute of Medical Sciences, New Delhi|
|Published on line in August 2002|
This 21-year-old man presented with the chief complaint of a single episode of generalized tonic clonic seizures in November 1999 from which he recovered completely. There was no history of headache, vomiting or any sensory or motor deficit. General physical examination and central nervous system examination revealed no abnormality. Contrast enhanced computerized tomography (CECT) of the head revealed a cystic lesion with enhancing nodule in the right frontal region (Fig. 1). MRI confirmed the solid-cystic nature of the lesion (Fig. 2). Based on radiological data, various differential diagnoses considered were pilocytic astrocytoma, ganglioglioma, pleomorphic xanthoastrocytoma and hemangioblastoma. A right frontal lobectomy was done. The lesion was encountered at a depth of 2 cm in the cerebral cortex and was excised.
Sections examined from the lesion showed a biphasic pattern. In solid areas, tumor cells were spindle shaped with nuclear palisading (Fig. 3). In some of the more cellular areas there were palisading nuclei with adjacent anuclear zones. The other areas were sparsely cellular, with cells loosely arranged in a myxomatous background (Fig. 4). Blood vessels were thick walled and hyalinized. There was evidence of old hemorrhage in the form of hemosiderin pigment deposition. The tumor did not show mitosis or necrosis. Reticulin stains revealed the tumor to be reticulin rich (Fig. 5) and Masson trichrome showed mature collagen formation with the tumor. The tumor was well demarcated from the surrounding brain parenchyma.
Immunohistochemistry for S-100 protein showed diffuse nuclear and cytoplasmic positivity. Focal cytoplasmic positivity for glial fibrillary acidic protein (GFAP) was also present. Tumor cells were however negative for synaptophysin, neurofilament, cytokeratin (CK) and epithelial membrane antigen (EMA). Electron microscopy revealed spindle shaped cells with scant cytoplasm and numerous cellular processes with basal lamina (Fig. 6). No intracellular intermediate filaments were identified.