[A case of retroperitoneal solitary fibrous tumor].

Solitary fibrous tumor (SFT) is a common neoplasm of the pleura and rarely arises from the retroperitoneal space. We report a case of retroperitoneal SFT. A 54-year-old woman was admitted to the department of dermatology in our hospital for examination and treatment of malignant melanoma of the right lower leg. Computerized tomography (CT) showed the left adrenal mass measuring 6.0 x 4.5 x 10 cm. Because the tumor was thought to be left adrenal tumor or left adrenal metastasis of the malignant melanoma, she admitted to our department. Left radical adrenalectomy was performed. The histological examination of the specimen revealed that the spindle or oval cells proliferated patternless with hyalinized collagen cells and there were few mitotic figures. The tumor was not connected to the adrenal gland. The immunohistochemical examination showed that the tumor cells were diffusely positive for CD34, bcl-2 and vimentin. According to these findings, we diagnosed SFT arising from the retroperitoneum. At 5 years follow up she had no evidence of local recurrence and no distant metastasis.