Abstract
Extranodal NK/T-cell lymphoma, nasal type, accounts for less than 3％ of all malignant lymphomas in Japan, and is rarely reported in the field of oral lesions. In this report, we describe a case of extranodal NK/T-cell lymphoma, nasal type, which was suspected to be focal myositis of the masseter muscle.
The patient became aware of discomfort in the right mandibular angle. She was diagnosed with focal myositis of the masseter muscle in the Department of Oral Surgery of another hospital, and received steroid therapy. The swelling worsened and she was referred to our department. No abnormal findings were found in the oral cavity or jaw that could have caused the swelling of the masseter muscle, so the patient was placed under observation. Six months after the initial visit to our department, the swelling worsened again, and steroid therapy was not effective. A muscle biopsy was performed under the diagnosis of focal myositis, and the histopathological result was extranodal NK/T-cell lymphoma, nasal type. Chemotherapy was commenced, followed by a cord blood transplantation. Four years after the initial visit, she is in good general condition with no recurrence.
