Synchronous Melanoma and Follicular Lymphoma in the Same Nodal Basin: A Diagnostic and Therapeutic Challenge

The incidence of both malignant melanoma (MM) and non-Hodgkin lymphoma (NHL) has risen in recent decades, with studies suggesting a potential bidirectional association. Nonetheless, synchronous presentation of active disease in both entities remains rare.

We report the case of a 62-year-old man with a history of indolent B-cell lymphoma, exhibiting features between marginal zone and follicular subtype, previously treated with R-CHOP, radiotherapy, and Rituximab maintenance, achieving complete remission. Ten years later, he developed an ulcerated superficial spreading melanoma (Breslow thickness 4.5 mm, pT4b), with staging CT revealing right axillary lymphadenopathy. Biopsy confirmed relapsed follicular lymphoma. Surgical management included wide excision and sentinel lymph node biopsy, which identified melanoma metastasis in one sentinel node and confirmed FL in the non-sentinel node. Molecular testing showed a BRAFV600E mutation. The patient received axillary radiotherapy followed by adjuvant BRAF/MEK inhibitor therapy.

At 6-month follow-up, imaging showed no evidence of relapse. This represents the first documented case of synchronous stage III BRAF-mutated MM and FL managed with targeted BRAF/MEK inhibitors combined with localized radiotherapy. The successful outcome validates this sequential multidisciplinary approach and underscores the importance of dermatologic surveillance in NHL survivors.