Cerebellar liponeurocytoma: morphological, immunohistochemical, and ultrastructural study of a relapsed case.

Cerebellar liponeurocytoma is a rare and newly identified neoplasm found in adults which is reputed to be benign. Its salient morphological characteristics are advanced neuronal/neurocytic differentiation, the presence of lipomatous areas, low mitotic rate, and the absence of necrosis, pleomorphism and vascular hyperplasia. Reported is a case of relapsing liponeurocytoma which occurred 3 and a half years after the radical excision of the primary lesion. Histopathological aggressive features (mitoses and a high proliferation index as evaluated by MIB-1) were shown in the primary lesion and recurrence of the tumor. We suggest that liponeurocytoma is an uncertain malignant potential lesion when mitoses are present and the MIB-1 positive cells are more than 10%.