The diagnosis of non-small cell lung cancer is in 50% of the cases not made until the metastatic stage. Distant metastases commonly involve the adrenal glands, the liver, the bones and the central nervous system. Metastases are very rarely seen in skeletal muscles. We report a case with a 47-year-old man, who suffered from strong pain in his right shoulder. The symptoms turned out to be the initial presentation of a disseminated lung cancer. A magnetic resonance scan showed skeletal muscle metastases to m. subscapularis and m. infraspinatus. Metastases to skeletal muscles are rare but should be kept in mind as part of the differential diagnosis in cases where atypical shoulder pain is the only symptom.