A Case Report of Primary Extranodal Diffuse Large B-Cell Lymphoma Involving the Masseter Muscle: Histological-Radiological Correlation

Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common type of non- Hodgkin’s lymphoma (NHL). However, the primary skeletal muscle involvement of DLBCL is extremely rare, comprising less than 1% of all the extranodal lymphoma. To date, only 8 cases of extranodal NHL involving the masticator muscles have been reported in the literature. Case Presentation: A 70-year-old male presented with a rapid progression of painless facial swelling in the left cheek. CT, MRI and US findings demonstrated a well-defined, soft tissue mass in the left masseter muscle. The histopathological diagnosis was DLBCL by US-guided core needle biopsy. The patient received three cycles of chemotherapy. Conclusion: Because of its rarity, primary muscular DLBCL must be considered in differential diagnosis with all possible causes of intramuscular masses. Even the integration of multiple imaging methods does not lead to a definitive diagnosis, the biopsy is the only possibility for an early diagnosis. Therefore, clinical awareness and high suspicion of this disease are important for early diagnosis and proper treatment.