Retained surgical sponge in the thigh: report of the third known case in the limb.

We report a retained surgical sponge (gossypiboma) in the thigh, which mimicked a neoplasm. A 25-year-old man, who had a past history of external fixation for femoral shaft fracture, complained of swelling in the left thigh with pain. A radiograph of the thigh showed periosteal reaction. T1-weighted magnetic resonance (MR) images showed a well-defined mass with heterogenous signal intensity, and T2-weighted images showed tortuous lines of low signal intensity within the mass. Surgical excision revealed a retained gauze sponge within the mass. Histopathological examination revealed foreign body reaction related to the retained gauze sponge. Our case, the third to our knowledge of gossypiboma in a limb, demonstrated characteristic MR imaging findings.