Primary psoas abscess.

Infectious processes in the retroperitoneal space often involve the psoas muscle. These infections usually are secondary to other intra-abdominal or intrapelvic inflammatory processes but rarely they will arise primarily within the retroperitoneum. These primary infections occur most often in younger patients and usually will demonstrate a chronic illness in which the diagnosis often is missed. We describe a 22-year-old man with a 2-year history of symptoms before the diagnosis was confirmed. The clinical presentation of the process and pathophysiology are discussed briefly.