Recurrent anaplastic ganglioglioma: pathological characterization of tumor cells

✓ A total resection of a left frontal lobe tumor in a 26-year-old man revealed differentiated ganglioglioma with small foci of atypical glial cells exhibiting mild atypia. Six and one-half years later, a large, well-demarcated tumor recurred; at that time, histological analysis revealed both typical ganglioglioma and highly cellular anaplastic areas, the latter predominating. Although the patient subsequently underwent total and subtotal resections, radiation therapy, and chemotherapy, tumors continued to recur at progressively shorter intervals and he died at the age of 35 years. Biopsies of tissue obtained at the last three resections and the autopsy revealed only anaplastic tumor cells. Routine histological examinations indicated that these tumors were uniformly composed of undifferentiated cells. However, pathological studies using immunohistochemical analysis, electron microscopy, and immunoblot analysis demonstrated that a small number of recurrent anaplastic cells had astrocytic features. Results of Ki-67/MIB-1 labeling and silver nucleolar organizer region counts for those cells were high for glial tumors. A retrospective study of the initial tumor showed slightly high MIB-1 labeling for atypical glial cells. This case is characterized by pathological findings of recurrent tumors that correspond to an unusual form of malignant glioma exhibiting slight astrocytic differentiation. The present case suggests that a longer follow-up period (> 5 years) is necessary in cases of ganglioglioma with mild atypia and that careful examinations, including proliferating potential analysis of initial tumor cells, could be important for the diagnosis and treatment of ganglioglioma.