Primary orbital leiomyoma and leiomyosarcoma.

A case of an extremely rare primary orbital leiomyoma in a 25-year-old male patient is presented who had a lifelong history of deviation of the left eye globe with slight enophthalmos and reduced motility. Because of pain and increasing deviation of the eye the tumor was totally resected. On histologic examination the tumor showed ossification which is extremely rare so that a calcifying fibroma had to be ruled out. In immunohistochemistry, however, this tumor stained with smooth muscle antigen. Less than 2% of cells stained positive for Ki-S1, a proliferation marker. The second case is a rare primary orbital leiomyosarcoma in an 84-year-old female patient that showed massive growth. After exenteration histologic examination showed a dedifferentiated highly malignant soft tissue tumor which expressed desmin and smooth muscle actin but was negative for myoglobin, S-100 and HMB-45.