Neoplastic iliopsoas masses in oncology patients: CT findings.

The aim of this study is to evaluate the imaging features of neoplastic iliopsoas masses detected on abdominal CT and determine the association with other metastatic sites in the abdomen. Thirty-three patients with a neoplastic mass detected in the iliopsoas muscles on a CT were included in this study. The CT were evaluated for imaging features of the focal psoas lesion and for the presence of additional metastatic disease in the abdomen. All 33 patients had a history of primary neoplasm. The most common primary neoplasms were renal in five, melanoma in four, lung in three, pharyngeal in three, colorectal in two, ovarian in two and other neoplasms in 14 patients. Although the majority of the iliopsoas masses were of lower density than the muscle, four patients had a mass with hyperdense ring and four other patients had a uniformly hyperdense mass on contrast enhanced CT. Eight (24%) patients had gluteal muscle metastases and 6 (18%) had subcutaneous metastases. Secondary iliopsoas neoplasms are most commonly hypodense lesions and are most commonly due to primary neoplasm from renal, lung, pharyngeal, ovarian, colorectal neoplasm and melanoma. The detection of an iliopsoas mass warrants a careful search for gluteal muscles and subcutaneous metastases.