Sellar hemangiopericytoma mimicking pituitary adenoma

Abstract

This 60-year-old woman was admitted to our hospital complaining of right visual disturbance and double vision. Examination on admission revealed incomplete bitemporal hemianopia. Her bestcorrected visual acuity was 6/20 in the right eye. Endocrinological examinations revealed anterior hypopituitarism with the following values determined in static testing: LH, ,0.5 mIU/mL (normal, 4.2–79.6 mIU/mL); FSH, 7.7 mIU/mL (normal, 12.6– 235.7 mIU/mL); adrenocorticotropic hormone, 17 pg/mL (normal, 6–36 pg/mL); prolactin, 62.6 ng/mL (normal, 1.4–14.6 ng/mL); GH, 1.34 ng/mL (normal, 0.28–8.7 ng/mL); morning cortisol, 1.2 mg/dL (normal, 3.0–15.2 mg/dL). The mass lesion showed isointensity on T1-weighted MR images, iso-intensity, including partial high intensity on T2-weighted MR images, and strong enhancement by Gd-DTPA. Right carotid angiography demonstrated opening of the carotid siphon and tumor staining fed by the branches of meningohypophyseal trunk. We chose the transsphenoidal approach based on a clinical diagnosis of pituitary adenoma. In surgery, much bleeding was encountered, which made tumor removal impossible. We could not obtain pathologic confirmation. After the operation, incomplete bitemporal hemianopia did not change. We judged optic nerve decompression and pathological confirmation to be necessary; therefore, we performed a right frontal craniotomy and removal of the tumor 2 months after the first operation. We obtained sufficient optic nerve decompression but total removal of the tumor was not attempted because of uncontrollable bleeding. Pathological examinations revealed perivascular proliferation of polygonal cells. The cells had low differentiation and were spindle-shaped, with a narrow cytoplasm and a large nuclear-cytoplasmic ratio. Immunohistochemical staining was negative for epithelial markers such as epithelial membrane antigen (EMA) and keratin, but positive for vimentin, CD34, factor XIIIa, collagen IV, and HLA DR. MIB-1 staining index was 2.16%. Electron micrograph revealed tumor cells with irregular nuclei that were closely adjacent. In the cytoplasm, many intermediate filaments and well-developed endoplasmic reticula were seen. There were neither cell junctions such as desmosome nor interdigitations, which are typical of meningioma. Pituitary adenoma and meningioma were excluded. The pathological diagnosis was HPC. Because of the malignancy and radiosensitivity of HPC, we treated the residual tumor with fractionated stereotactic radiosurgery by using a linear accelerator. A single 20-mm diameter Address reprint requests to: Dr Yoshie Kanda, Department of Neurosurgery, Nagoya City University Medical School, Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8602 Japan. Received June 22, 2000; accepted October 31, 2000.