Ryoji Arima

Traumatic myositis ossificans in the masseter muscle

Traumatic myositis ossificans in the left masseter muscle of a 25-year-old man is described. The lesion, which extended intramuscularly from the lateral surface of the zygomatic bone to the mandibular angle, was resected by an intraoral approach. The specimen was composed of mature cortical bone in the outer portion and spongy bone, including degenerated muscle fibers and marrow spaces, in the inner portion. At the lower end of the specimen was a sequence of bone formation involving fibrous connective tissue, cartilage, woven bone, and mature lamellar bone with many osteoblasts. Clinicopathologic features of 26 reported cases of traumatic myositis ossificans of the maxillofacial region are reviewed, and the pathogenesis of the disease is discussed.

Clinical aspects of lymphatic metastasis and prognosis of squamous cell carcinomas in the oral region

A clinical evaluation of lymphatic metastasis was carried out on previously-untreated 104 patients with squamous cell carcinoma in the oral region.Exact metastases, evaluated by microscopy, to the submandibular, middle cervical, upper cervical and submental nodes appeared in the above order of frequency. Few metastases were observed in the other parts of the cervical lymph nodes. Relatively higher frequency of metastasis to the cervical lymph nodes was detected in patients with primary lesions of the gingiva of the upper jaw, buccal mucosa, gingiva of the lower jaw, floor of the mouth and tongue.Later metastasis to the cervical lymph nodes after the primary treatment was observed at relatively low rates in patients with tumor of the maxillary sinus, gingiva of the lower jaw and oropharynx, as compared to tumors of the upper jaw, buccal mucosa, floor of the mouth and tongue. Patients survival rate closely related to whether or not the later metastasis to the cervical lymph nodes occured while no significant correlation between the existence of metastatic lymph nodes before treatment and the patients survical rate was detected. However, no definitive factor influencing the later metastasis could be found in the present study.