Synchronous Presentation of Nodular Melanoma and Epithelioid Cell Melanoma: Case Report.

The synchronous occurrence of melanomas of varying histological types is an uncommon event, with reported incidences ranging from 0.2% to 8.6%. We present the case of a patient diagnosed with Stage IIB nodular melanoma and Stage IIIC epithelioid cell melanoma within a 3-month period. After surgical excision of both lesions, lymph node enlargement was observed in the obturator region, indicating metastatic spread. As a result, combined immunotherapy with nivolumab and ipilimumab was initiated. Nivolumab and ipilimumab were administered at doses of 1 and 3 mg/kg, respectively, every 3 weeks for a total of four doses. Thereafter, treatment was continued with nivolumab alone at a dose of 3 mg/kg every 2 weeks. The patient underwent three cycles of immunotherapy, initially combined with intravenous methylprednisolone, later transitioned to an oral regimen with dexamethasone. The patient initially demonstrated a favorable clinical response without adverse effects. However, after the third infusion, severe diarrhea developed, leading to daily fluid losses exceeding 8 L and associated hypokalemia. Therefore, methylprednisolone was administered intravenously (2 mg/kg/day). Additionally, the patient experienced a splenic infarction that resolved spontaneously without resulting in asplenia. At the most recent follow-up evaluation, no lymph node enlargement was detected, and surveillance continues at 3-month intervals. Although rare, the simultaneous emergence of melanomas at distinct anatomical sites underscores the necessity for increased patient vigilance and comprehensive clinical monitoring to facilitate early detection and timely intervention. Prompt initiation of targeted immunotherapy may improve patient prognosis and outcomes.