2025 Volume 24 Issue 1 Pages 74-79
A 55-year-old woman presented to our hospital with a chief complaint of a black nodule on the vulva. A 2 cm-sized mass with partial ulceration was found on the right genital mucosa, and a partial biopsy was performed, which resulted in a diagnosis of mucosal-type malignant melanoma. After extended resection and sentinel lymph node biopsy, the patient was diagnosed with pT4bN2aM0 Stage pIIIC according to the AJCC 8th edition. PD-L1 expression was ＞90%, and the BRAF mutation was wild type. The patient received four courses of pembrolizumab (400 mg/dose) as post-operative adjuvant therapy, but multiple lymph node metastases emerged. Subsequently, she underwent four courses of combination therapy with nivolumab (80 mg/dose) and ipilimumab (135 mg/dose). However, liver metastasis appeared, and the lymph node metastasis increased, leading to her being considered a primary invalid case. She then underwent five courses of transcatheter arterial chemoembolization for liver metastases as well as radiotherapy (80 Gy/20 Fr) for the lymph node metastases. In addition, carboplatin (563 mg/dose) and paclitaxel (298 mg/dose) were administered, which initially reduced the metastases ; however, new liver metastases appeared again. FoundationOne○R gene panel examination revealed a KIT L576P mutation and KIT amplification, which led to the introduction of imatinib (400 mg/day). After starting imatinib, the liver metastases did not increase for 13 months, showing a prolonged prognostic effect. Herein, we report a case of immune checkpoint inhibitor-resistant mucosal melanoma in a patient, where the gene panel examination expanded an effective therapeutic option with the c-kit inhibitor, imatinib. Skin Research, 24: 74-79, 2025
