Diffuse large B-cell lymphoma of the right upper extremity misdiagnosed as soft tissue infection

Diffuse large B‑cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL). It can originate in both lymph nodes and extranodal sites. Primary skin or soft tissue involvement of DLBCL is extremely rare and lacks specific clinical symptoms, making early diagnosis difficult. We report the case of a 48-year-old woman who initially presented with fever, redness, swelling, and pain in the right upper extremity without a palpable mass. A recent history of trauma led us to initially diagnose soft tissue infection. However, when the soft tissue infection did not respond to antibiotics, a pathological diagnosis of DLBCL was made following surgical amputation. This case highlights the complexity of diagnosing primary DLBCL in unusual locations and highlights the importance of timely and accurate diagnosis. Clinicians must remain vigilant and consider primary DLBCL as a potential diagnosis, especially in unusual sites.