Radiation Monotherapy for Primary Cutaneous Diffuse Large B-cell Lymphoma, Leg Type: A Case Report.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), is a rare and distinct subtype of non-Hodgkin lymphoma. PCDLBCL-LT is characterized by malignant B-cell proliferation within the skin, often presenting as erythematous nodules or plaques primarily affecting the lower extremities. Differentiating PCDLBCL-LT from other primary cutaneous B-cell lymphomas (CBCLs) can be difficult. However, an accurate diagnosis is crucial to identify the appropriate treatment. Once diagnosed, chemotherapy, including rituximab as a monotherapy or combined with doxorubicin, cyclophosphamide, vincristine, and prednisone (R-CHOP), is the standard treatment for PCDLBCL-LT; yet many PCDLBCL-LT patients are elderly and frail, making them poor candidates for chemotherapy. Radiation monotherapy may be a more appropriate treatment for these patients, particularly those with localized lesions, because of its excellent local control, favorable toxicity profile, and overall survival (OS) comparable to chemotherapy alone. In this report, we present the case of a 93-year-old woman with stage II leg-localized PCDLBCL-LT who declined to receive systemic therapy due to her concerns regarding her age and fragility. The patient achieved a complete metabolic response following a hypofractionated course of radiation monotherapy and remained disease-free at her five-year survival follow-up, supporting the suggestion that radiation monotherapy may be an effective treatment approach for select elderly patients.