[Muscle metastases of cancers]

In a retrospective study of cancer patients seen between 1980 and 1990, 7 cases of metastases to skeletal muscles were found: 2 primary bronchial carcinomas, 1 spindle cell sarcoma, 1 malignant melanoma, 1 ovarian adenocarcinoma, 1 squamous cell laryngeal carcinoma and 1 malignant neuroendocrine tumor from an unknown primary site. Despite their rich blood supply, skeletal muscles are rarely secondary metastatic sites (less than 1% of all malignant metastases of hematogenous origin); only 242 cases have previously been reported in 82 publications. Primary cancers of the lung, blood, gastrointestinal tract and genitourinary tract were the most frequently involved. Although skeletal muscle metastatic sites were rarely observed, the possibility of such a colonization should be known to physicians, as their detection requires specific tests. Furthermore, the localization of such sites clearly illustrates the recent progress made in the biology of metastases, especially the organ--or tissue--specificity of the site.