Polymyalgia rheumatica-like presentation in a case of diffuse large B-cell lymphoma: a diagnostic pitfall.

Diffuse large B-cell lymphoma (DLBCL) commonly presents with systemic manifestations including fever, weight loss, and night sweats. Uncommonly, patients with DLBCL can present with musculoskeletal manifestations mimicking polymyalgia rheumatica (PMR). Herein, the case of a 61-year-old woman who presented with pain in the bilateral shoulders, arms, hands, knees, pelvic girdle, and neck with bouts of fever, is presented. Laboratory workup for infectious and connective tissue diseases was non-revealing, except for elevated inflammatory markers. A positron emission tomography (PET)/computed tomography (CT) scan was suggestive of PMR, but also revealed enlarged lymph nodes initially thought to be reactive in nature. However, a lymph node biopsy showed findings consistent with DLBCL. This case highlights the importance of a thorough investigational workup when cases with features of PMR do not meet the proper criteria for this diagnosis to be made, in order not to miss a hematopoietic neoplasm with a PMR-like presentation.