Adenocarcinoma of the lung metastatic to the psoas muscle.

Hematogenous metastasis to the psoas muscle is rare, and the resulting clinical symptoms may mimic psoas abscess or hemorrhage. When the clinical history is not specific, CT is important in documenting the presence of a psoas mass and providing biopsy guidance for histologic diagnosis. Only three previously reported cases have been related to a primary carcinoma of the lung.