Unilateral piriformis syndrome in a patient with previous melanoma

Several years after undergoing surgery for a malignant melanoma on his left lower back, a 51 year old man developed intermittently severe pain in his left posterior thigh. Plain X-rays showed no abnormality, but computerized tomography and magnetic resonance imaging scans demonstrated an abnormal soft tissue mass in the left sciatic notch. Although a metastasis from the original melanoma was suspected, exploration of the suspicious area revealed only hypertrophy of the left piriformis muscle. This was due to regular gymnasium exercises designed to selectively build up the musculature of the left lower limb, which the patient had undertaken in the firm belief that it would help to prevent a recurrence of his left-sided melanoma. Complete relief of the unilateral piriformis syndrome was achieved by division of the hypertrophied piriformis muscle, thereby relieving the pressure on the left sciatic nerve as it passed through the greater sciatic foramen.