Anaplastic large cell lymphoma in the penis: a case report and review of literature.

BACKGROUND: Anaplastic large cell lymphoma is a distinct subtype of mature T cell lymphoma characterized by strong CD30 expression. While primary penile lymphomas are rare, they are most commonly of B cell origin, making primary T cell lymphomas of the penis an exceptional finding that can pose significant diagnostic challenges. CASE PRESENTATION: A 60-year-old Arab male presented with multiple, rapidly growing nodules on the penile body that had developed over 4 weeks. A comprehensive workup, including biopsy and immunohistochemistry, confirmed a diagnosis of localized, anaplastic lymphoma kinase-negative primary cutaneous anaplastic large cell lymphoma. Staging via positron emission tomography-computed tomography revealed no systemic involvement. The patient was treated with six cycles of brentuximab vedotin plus cyclophosphamide, doxorubicin, vincristine, and prednisone, achieving a complete metabolic response (Deauville score of 2) as assessed by post-treatment positron emission tomography-computed tomography imaging. CONCLUSION: This case highlights the diagnostic challenge posed by rare penile lesions and, more importantly, the therapeutic dilemma of selecting an appropriate treatment for a disease that is localized yet multifocal. The successful outcome with systemic brentuximab vedotin plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy, a deviation from standard guidelines for unifocal primary cutaneous anaplastic large cell lymphoma, underscores the need for individualized treatment strategies and further research to establish risk-adapted guidelines for this rare clinical entity.