Sirs: Skeletal muscle is one of the most unusual sites of metastasis from any malignancy, although it comprises a large part of the body and receives abundant blood supply. Only a few cases of macroscopic muscle metastasis have been described in the literature. Here we report a patient with extensive myosclerosis and rapidly progressive contractures owing to metastatic infiltration of skeletal muscle.A 61-year-old man presented with a 1-month history of rapidly evolving, painful restriction of mobility of his right arm and his legs. On examination, there was a complete flexion contracture of the right elbow and an abduction contracture of the hips so that he could walk only with his legs wide apart (Fig. 1). His muscles were of wooden consistence, and firm little masses could be palpated. Two weeks after admission, the patient lost his ability to walk. He could only lie on two adjacent beds.Electromyography showed marked spontaneous activity with fibrillations and positive sharp waves as well as a myopathic voluntary pattern in close proximity to the palpable firm masses in the right biceps and the left quadriceps muscle. In contrast, muscle areas distant to the masses showed a normal electromyographic appearance.Radiographs of the right elbow and of the hips showed severe and progressive contractures, but no soft tissue calcification or osteolytic lesions. Thoracic computed tomography (CT) on admission revealed mild enlargement of the left pectoralis muscle; repeat CT 2 weeks later showed marked progression of this thickening (Fig. 2). CT of the neck revealed a metastatic nodule infiltrating the left sternocleidomastoid muscle and a mass in the left oropharynx (Fig. 3). CT of the pelvis showed multiple hypodensities of the gluteal and psoas muscles (Fig. 4) without involvement of the bone. Magnetic resonance imaging (MRI) could not be performed because of the hip abduction contracture.A muscle biopsy specimen was taken from the left quadriceps muscle and from the right gluteus maximus. The biopsy specimens showed pronounced fibrosis and extensive infiltration of the muscle with carcinoma cells (Fig. 5). The carcinoma cells showed enlarged hyperchromatic nuclei and numerous mitoses. Immunohistology was markedly positive for keratin, but negative for chromogranin, prostate-specific acid phosphatase, melanoma antigen HMB 45 and S 100 protein. These results confirmed the diagnosis of a LETTER TO THE EDITORS J Neurol (1998) 245 : 749-752 © Springer-Verlag 1998 Fig. 1 Patient with flexion contracture of the right elbow and abduction contracture of the legs Fig. 2 Thoracic computed tomography (CT) scan showing metastatic infiltration of the left pectoralis muscle (arrows)