Primary gingival diffuse large B‑cell lymphoma with muscle invasion: A case report

Primary gingival diffuse large B-cell lymphoma (DLBCL) with muscle invasion is rare and accounts for ~0.5% of all reported cases of extranodal lymphoma. The present study describes the case of a 49-year-old man that initially presented at Yingshan County People's Hospital (Nanchong, China) in August 2017 with a chief complaint of tenderness and swelling of the jaw. Computed tomography revealed a mass in the gingiva, and enlarged lymph nodes in the cervical, mediastinal and gastro-hepatic ligaments. Histological examination indicated the gingival mass was a DLBCL, which was positive for CD20, BCL-6, BCL-2, C-MYC and MUM1. The patient received three lines of anti-neoplastic therapy (R-CHOP, R-CHOEP and SYHX1903) and achieved stable disease for 6 years. Subsequently, the patient experienced trauma in the left forearm due to a car accident and the subsequent color Doppler imaging led to a diagnosis of muscular hematoma; however, magnetic resonance imaging and biopsy of the forearm muscle confirmed DLBCL invasion. Due to the patient suffering from heart failure after the third line of the previous chemotherapy, palliative radiotherapy was administered to the left forearm, and the patient achieved a partial response. In conclusion, primary gingival DLBCL with muscle invasion is rare and easily misdiagnosed, and individualized treatment should be considered for these complex cases.