An Unusual Presentation of Diffuse Large B-Cell Lymphoma With Penile Metastasis.

Diffuse large B-cell lymphoma (DLBCL) is a high-grade B-cell lymphoma that most commonly presents with lymph node involvement. Extranodal manifestations are seen in around 40% of the cases involving the gastrointestinal tract, thyroid, testes, brain, and breast, among many others. However, penile metastasis is extremely rare and often overlooked in routine clinical evaluations. We present the unique case of a 79-year-old man with a history of DLBCL with extranodal involvement who achieved remission after completing five cycles of chemotherapy and presented eight months later with a new penile mass. A PET-CT scan of the skull to mid-thigh revealed bilateral pulmonary nodules, multiple lesions in the pancreas, retroperitoneal nodules, and an increased uptake at the base of the penis, leading to a biopsy of the penile mass that confirmed recurrent DLBCL with penile metastasis. The patient subsequently underwent surgical excision of the lesion and additional chemotherapy. This case underscores the importance of considering atypical sites of involvement in DLBCL patients and emphasizes the need for a timely diagnostic workup to ensure early detection and accurate diagnosis. By raising awareness of this rare manifestation and promoting comprehensive evaluations, we can potentially improve patient outcomes and facilitate the development of more effective treatment strategies.