Spontaneous giant expanding thigh hematoma mimicking soft tissue neoplasm.

We present a case of giant chronic expanding hematoma occurring in the left lateral thigh without any history of trauma or chronic medical disease. In our case, a diagnosis was unable to perform through conventional diagnosis method, which was confirmed by histopathological examination after successful surgical treatment. We suggest that patients who present with slowly growing extremity masses without trauma, in addition to soft tissue sarcoma and malignancy, chronic expanding hematoma should be considered in the differential diagnosis.