Forearm muscle metastasis as an initial clinical manifestation of lung cancer.

Skeletal muscle metastasis from lung cancer is rare, and the optimal treatment strategy is unknown. A 37-year-old man presented with painful swelling in the left forearm. A biopsy of the swollen muscle disclosed the presence of pulmonary adenocarcinoma. The patient was treated with systemic chemotherapy and radiotherapy; radiographic examination revealed a marked reduction of the tumor in the primary site and muscle metastasis. Skeletal muscle metastasis as a mode of presentation of primary lung cancer is an unusual phenomenon.