22. Small cell glioblastoma

We report three cases of small cell glioblastoma selected out of a series of 324 consecutive glioblastomas from January 1988 to December 1996. Case 1: A 45 yr-old man showed an expanding mass of the right cerebellar emisphere. He died six months following surgery. Case 2: A 61 yr-old lady showed a haemorrhagic lesion of the right frontal and temporal lobes with mass effect. She died one day after surgery. Case 3: A 58-yr-old man showed a large lesion of the right frontal and parietal lobes which increased rapidly. He is alive with disease 6 months following surgery. In all the patients, no tumors were discovered outside the central nervous system despite the extensive clinical investigations. The lesions were previously misdiagnosed as undifferentiated tumors of probable metastatic origin because they lacked areas of clear-cut glioblastoma with palisading necrosis, endothelial hyperplasia and immunocytochemically detectable expression of GFAP. The three cases were diffusely immunoreactive with anti-vimentin antibody whereas, in addition to anti-GFAP, the other antibodies employed including anti-cytokeratin, anti-synaptophysin and anti-neurofilaments gave negative reactions. Glial differentiation was only evident at electron microscopy since neoplastic cells contained sparse cytoplasmic glial filaments.