Aneurysmal bone cyst in the first rib.

Aneurysmal bone cyst is a benign tumor of the skeletal system that rarely occurs in ribs. We report two cases of aneurysmal bone cyst in the first rib. The first patient was a 21-year-old woman with an aneurysmal bone cyst in the left first rib that was resected with an L incision. The second patient was a 42-year-old man with an aneurysmal bone cyst in the right first rib that was resected with a posterolateral incision but recurred 1 year later. An en bloc resection was performed, without recurrence to date. We also review this disease with emphasis on the etiology, clinicopathology, and treatment approaches.