Adult rhabdomyoma: ultrastructure and immunocytochemistry

Adult rhabdomyoma is a benign, highly differentiated tumor of skeletal muscle. We observed transverse tubules and triads beside myofilaments in a rhabdomyoma from the submandibular area of a 66-year-old woman. Several types of muscle cells were present. In one, mitochondria abounded; in another, muscle filaments predominated. Myoglobin was also detected in the tumor.