Extraskeletal aneurysmal bone cyst: Report of a case and review of the literature.

Aneurysmal bone cyst (ABC) is an expansile cystic lesion that may affect any bone of the skeleton. Although exceedingly rare, lesions with histomorphologic characteristics of an ABC have reportedly originated within soft tissue. Extraskeletal ABC may mimic a variety of benign and malignant lesions and can be confused with other more common or rare giant cell-rich tumors of soft tissue, especially myositis ossificans. Clinical, radiological and histologic correlation is crucial in reaching the correct diagnosis. Cytogenetic and/or molecular genetic analysis is a useful adjunct in diagnosing these exquisitely rare lesions. Here we report a case of an ABC arising in an extraskeletal site and provide a comprehensive review of literature on this rare entity.