A Case of Alveolar Soft Part Sarcoma in the Orbit Diagnosed as C avernous Hemangioma befo re Operation

ABSTRACT

Alveolar soft part sarcoma is a very rare malignant neoplasm which originates from the soft tissue. The common site is lower extremity and it is especially rare to occur primarily in the orbit. It is characterized that tumor shows organoid arrangement of lobules separated by numerous delicate vascular septa and individual tumor cell contained PAS positive crystalline granules in the cytoplasm. Moreover, because of hypervascular tumor, it is easy to misdiagnosed as a cavernous hemangioma which commonly occurs in the orbit. We experienced a 29-year-old male who had suffered from unilateral proptosis.Before operation, ultrasonography, MRI and single photon emission computed tomography (SPECT) were performed and we suspected that the retro-orbital mass was a cavernous hemangioma. Using Kr onlein method,lateral orbitotomy was performed and large well encapsulated tumor mass (2.5 x2.5 x2.0 cm)was excised. On histopathological examination the tumor was confirmed as an alveolar soft part sarcoma. Therefore, we report this interesting case with review of the literature.