Mandibular embryonal rhabdomyosarcoma with cartilaginous metaplasia: report of a case and review of literature.

Rhabdomyosarcoma (RMS) is a malignant tumor of skeletal muscle origin and frequently involves the head and neck region. It represents the second most common pediatric soft tissue sarcoma and accounts for 3% of all childhood cancers. Here, we report a case of embryonal RMS presenting as a right-sided facial swelling in a 7-year-old boy. Histologically, the tumor consisted of classic embryonal rhabdosarcomatous areas with metaplastic cartilage, in both initial biopsy and final resection specimens. Cartilaginous metaplasia arising in the background of RMS is a rare finding, thus raising a diagnostic challenge. To the best of our knowledge, this represents the first case of RMS with cartilaginous metaplasia in the oral cavity.