Malignant intracerebral granular cell tumor reacts positively with anti-alpha-1-antichymotrypsin and the MB2 antibody: a clue to the histogenesis of the brain granular cell?

A 50-year-old man developed a granular cell tumor (GCT) of the right hemisphere (parieto-occipital) with visual deterioration and headache. Two months after surgery the tumor relapsed with diffuse infiltration of the right hemisphere, the corpus callosum and the adjacent left hemisphere. Subsequently, radiotherapy (5000 rads) was applied. Controls two and four months after the radiotherapy did not show any signs of the tumor in the computerized tomogram (CT). Light- and electronmicroscopy showed typical type I (small) and type II (large) granular cells with irregularly rounded or oval nuclei, abundant cytoplasm and PAS positive granules. Immunohistochemistry was positive with anti-alpha-1-antichymotrypsin (ACT) and the MB2 antibody. A survey of the relevant literature is given with special emphasis on the impact of the results of immunohistochemistry on the histogenesis of the CNS granular cell. Finally, some aspects of the therapy of GCTs will be discussed.