Imaging and radiological-pathological correlation in granular cell astrocytomas. Report of two cases.

BACKGROUND: Granular cell astrocytoma is a rare and aggressive subtype of astrocytoma that is histopathologically well defined in the literature. It is formed by polygonal cells with granular cytoplasm mixed with neoplastic astrocytes and usually a perivascular infiltrate of lymphocytes. Despite its unusual histologic appearance, relevant radiologic features have not yet been described. CASE DESCRIPTION: We report 2 middle-aged patients with neurologic symptoms secondary to a newly diagnosed brain tumor. The absence of central tumor necrosis as well as the presence of an atypical pattern of enhancement and areas of intense diffusion restriction on magnetic resonance imaging in both cases led to the diagnosis of primary central nervous system lymphoma. Histopathologic findings in both tumors showed an aggressive astrocytoma with a prominent granular cell population and perivascular lymphocytic cuffing in tissue, corresponding to a granular cell astrocytoma. Despite the favorable prognostic factors, including World Health Organization grades II and III astrocytomas and IDH mutations, the outcome was poor. CONCLUSIONS: Granular cell astrocytomas can show unusual aggressive radiologic features that do not correspond to their histopathologic grade of malignancy. The presence of perivascular lymphocytic infiltrate may alter the typical radiologic appearance of common astrocytomas.