Bilateral cerebellar epithelioid hemangioblastoma with possible ependymal differentiation in a patient with von Hippel-Lindau disease.

There are controversies regarding the histogenesis of stromal cells of hemangioblastoma, and no hypothesis has conclusively been proven. We report a case of unusual hemangioblastoma in a middle-aged man with von Hippel-Lindau disease. Neuroimaging revealed multifocal gadolinium-enhancing masses were located within both sides of the cerebellar hemisphere. Histologically, only small areas showing the typical morphology of hemangioblastoma were recognized in masses. Most areas of masses were composed of cohesive epithelioid tumor cells with abundant cytoplasm and distinct boundaries. Epithelioid tumor cells were arranged around blood vessels, exhibiting perivascular anuclear zone structures like ependymoma. The epithelioid tumor cells were diffusely positive for vimentin, CD99, neuron-specific enolase, GFAP and focally positive for epithelial membrane antigen (EMA) and D2-40 in a dot-like pattern. Variable-sized lipid droplets and glycogen particles were noted in the cytoplasm of epithelioid tumor cells under an electron microscope. A diagnosis of epithelioid cellular hemangioblastoma with possible ependymal differentiation (WHO grade I) was made. To our knowledge, only a few cases of hemangioblastoma show epithelioid appearance or EMA immunoreactivity. The present case indicates that the stromal cells of hemangioblastoma might originate from primitive neuroectodermal cells, and they have the capacity to show a distinctive sign of glial or ependymal differentiation.