ABC-type diffuse large B-cell lymphoma presenting as rotator cuff tendinopathy: A diagnostic dilemma and review of the literature.

Diffuse large B-cell lymphoma often presents with extranodal manifestations involving the musculoskeletal system. Shoulder pain is particularly worrisome for malignancy. Individuals presenting with refractory upper extremity complaints should undergo a prompt and thorough evaluation for cancer, as a delay in diagnosis can result in an unfavorable outcome.