Muscle metastasis of carcinoma.

Metastatic carcinoma of the soft tissue is extremely rare compared with bone metastases. An intramuscular mass is often thought to be a primary soft tissue sarcoma because intramuscular metastases are very uncommon. Any painful soft tissue mass occurring in patients with a known history of carcinoma, particularly with extensive peritumoral enhancement associated with central necrosis, is highly suspicious for skeletal muscle metastasis. A needle biopsy is necessary for proper diagnosis. It is very important to make a differential diagnosis between metastasis and primary cancer in these cases. Here we present a review of known evidence.