histopathological and immunohistochemical evaluation of orbital spindle cell tumors

purpose: to assess the histopathological and immunohistochemical features of orbital spindle cell tumors. methods: a descriptive, retrospective study was performed on 63 pathology reports on all types of orbital spindle cell tumors at the pathology department of farabi hospital between 1995 and 2005. immunohistochemistry studies for different markers, such as smooth muscle actin, desmin, s100 protein, cd31, factor viii, cd 68 and cd34, were carried out in cases with indeterminate origin on routine histopathologic study to achieve a definitive diagnosis. results: our study included 63 cases with average age of 30 years including 62% female and 38% male subjects. the leading types of orbital spindle cell tumor in our study in order of frequency included: benign nerve sheath tumors (46.0), rhabdomyosarcoma (11.1%), hemangiopericytoma (7.9%), fibrous dysplasia (7.9%), ossifying fibroma (4.8%), fibrous histiocytoma (3.2%), and other types (19.1%). from 29 cases with benign nerve sheath tumor, 16 cases (25.4%) were neurofibroma and 13 cases (20.6%) were schwannoma. the orbital tumors were benign in 74.7% and malignant in 25.3%. conclusion:  the most common type of orbital spindle cell tumor in this study was benign nerve sheath tumor. immunohistochemical studies for different markers are required for definitive diagnosis of cases with indeterminate origin on routine histopathological study.