Penile diffuse large B-cell lymphoma in a young man.

Here, we present the case of a young man active-duty service member diagnosed with stage IE penile diffuse large B-cell lymphoma (DLBCL), germinal centre B-cell (GCB) subtype. Primary penile DLBCL is an exceptionally rare condition, with fewer than 30 cases reported in the medical literature. Notably, this patient is significantly younger than the typical demographic, as extranodal DLBCL affecting the penis usually occurs in elderly men, with a median age of 69 years at diagnosis. The treatment for limited-stage DLBCL generally depends on patient-specific risk factors and often involves a limited number of chemotherapy cycles, with or without localised radiation. Our patient received four cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP). In this case, we chose to forgo radiation therapy due to the positive response observed on the interim positron emission tomography scan. This case not only highlights the unusual occurrence of DLBCL in a young patient and at an uncommon site but also contributes valuable insights into the diagnosis and management of this rare lymphoma subtype.