[Solitary orbital fibrous tumor in a 12-year-old child]

Solitary orbital fibrous tumor was diagnosed in a 12-year old boy admitted to hospital for right-sided exophthalmos. MRI revealed orbital mass and surgical resection was performed. Histologically the tumor was composed of round or spindle cells with a lot of multinucleate giant cells and pseudovascular spaces. The neoplasm was regarded as a mixoid type of a solitary giant cell-rich fibrous tumor. Immunohistochemical analysis revealed coexpression of CD34, CD99, bcl-2, and CD99 (mic-2). The most important clinical, morphological, and immunohistochemical manifestations are presented in the paper. Major criteria for the differential diagnosis of solitary orbital fibrous tumor and the similar soft tissue tumors are discussed.