下顎に広範な歯肉壊死を伴った節外性NK/T細胞リンパ腫の1例

抄録

Extranodal NK/T cell lymphoma, nasal type, rarely arises in the oral cavity. We report the case of a 52-year-old man in whom the lesion originated in the left lower gingiva. The patient had slight pain and swelling at the left lower third molar region. Under a diagnosis of pericoronitis, the left lower third molar was extracted at a dental clinic. Because of a poor postoperative course, he was referred to our clinic. Intraoral examination revealed an ulcer and necrotic mucosa around the socket of the extracted third molar. CT scanning showed no bone resorption in the region around the extraction socket. Although the clinical findings suggested necrotizing ulcerative gingivitis, a biopsy revealed accumulation of atypical lymphocytes around the blood vessels. The biopsy specimen was positive for cytoplasmic CD3_ε, Epstein-Barr virus encoded small RNA 1 in situ hybridization (EBER 1/ISH), and granzyme B, and negative for CD56 and CD20. Genetic screening of the frozen specimen was negative for T cell receptor gene rearrangement (TCR). On the basis of these findings, a definite diagnosis of extranodal NK/Tcell lymphoma, nasal type, was confirmed. The patient was treated with 50 Gy of radiation and 3 courses of DeVIC (CBDCA, VP-16, IFO, DEX) chemotherapy. His general condition remarkably improved, and there were no signs of recurrence after treatment. Because of the poor prognosis for patients with this type of tumor, prompt diagnosis and treatment are very important.