Skeletal muscle metastasis secondary to cancer--a report of seven cases

Cancer metastasis to the skeletal muscle is very rare. In this report, we describe 7 cases (6 males, 1 female, age 55-76, mean 66 y.o.) with unusual presentation of cancer metastasis to the skeletal muscle, illustrating the principal clinical, radiographic and histologic features. The primary tumors were lung cancer in 4 cases (3 adenocarcinomas, 1 squamous cell carcinoma) and renal cell carcinoma, esophageal carcinoma, hepatocellular carcinoma in each one. The metastatic sites were the adductors, iliopsoas, rectus femoris, biceps bracii, triceps bracii, deltoid, and paravertebral muscle in each one. The unusual sites of metastases were visualized by CT and/or MRI and confirmed by needle or trocar biopsy. Five patients died in 2 to 24 months with the average of 8 months after initial examination.