Supratentorial Hemangioblastoma with Unusual Features

Hemangioblastomas of the central nervous system (CNS) are benign tumors that most commonly occur in the cerebellum, followed by the brainstem and spinal cord. 1 Supratentorial location is extremely rare. 2 CNS hemangioblastomas can occur sporadically or in association with von Hippel-Lindau disease. 2 Histologically, the tumors are composed of two main components: large and vacuolated stromal cells and numerous thin-walled vessels. Due to the characteristic lipid-containing cyto-plasm and foci of pleomorphic nuclei, the differential diagnosis of hemangioblastoma from some other malignant tumors, such as clear cell renal cell carcinoma (RCC), adrenal cortical carci-noma and paraganglioma, remains challenging, especially in cellular variants. Hyaline globules can be found in many different tumors and benign tissues, 3 including CNS hemangioblas-tomas, and they contribute to the diagnostic difficulty. Herein, we report a case of sporadic supratentorial hemangioblastoma with unusual features and discuss the differential diagnosis of CNS hemangioblastoma. A previously healthy 48-year-old female had developed weakness on the right side and clumsiness in the hands three weeks before admission. At an outside hospital, brain magnetic resonance imaging revealed a heterogeneously enhancing left frontal lobe mass measuring 3.3×2.6 cm (Fig. 1). The mass contained a cystic or necrotic component, and the radiologic differential diagnosis included metastasis and high-grade glioma. A craniotomy was performed, and the tumor was resected. During surgery, abnormal vascular structures both inside and around the tumor were found. Upon gross examination, the tumor was a soft and friable yellow mass. Microscopically, the tumor was well delineated from the surrounding brain parenchyma and characterized by an abundant arborizing capillary network and sheets of pleomorphic polygo-nal cells (Fig. 2A). The nuclear morphology of the tumor cells was variable: single or multiple (up to 10), round to elongated, dark or vesicular, pleomorphic or bizarre nuclei with often multiple or single prominent nucleoli, and frequent intranuclear cytoplasmic inclusions. The cytoplasm was abundant and eo-sinophilic or clear and occasionally uni-or multi-vacuolated (Fig. 2B). Tumor cells with eccentrically located nuclei and glassy cytoplasm were also identified. Neither necrosis nor mitotic activity was seen. Numerous extracellular and intracytoplasmic hyaline globules were observed (Fig. 2C). The presence of pleo-morphic, vacuolated clear cells and hyaline globules raised the suspicion of metastatic tumors including RCC, adrenal cortical carcinoma and hemangioblastoma. Immunohistochemical staining was done using the Leica Bond-Max automatic stainer. Antibodies used included the markers of RCC The tumor cells diffusely expressed vimentin and CD10, and they focally expressed S-100, α-inhibin, …