Gastric metastasis from nodular malignant melanoma of the auricle with multigene aberrations: A rare case report and literature review

Primary malignant melanoma (MM) of the external ear accounts for a low proportion of cases of cutaneous MM, and its incidence in non-white women is very low. The stomach is a rare metastatic site for MM. Gastric metastasis of MM of the external ear is extremely rare, and the associated gene alterations and mechanisms are poorly understood. The present report describes the case of a 58-year-old Asian woman who had a mass on the left auricle for 5 years and was diagnosed with nodular MM with the BRAF V600E mutation after surgical resection. Postoperative metastases to the stomach and descending duodenum appeared 1 year after resection. After 11 months of BRAF-targeted therapy and immunotherapy, the patient developed drug resistance and died from systemic metastases to the brain, lungs, liver, left adrenal gland and peritoneum. Genetic testing revealed additional aberrations in MYB, p16, MYC and PTEN. The clinical characteristics of MM of the external ear and gastric metastatic MM were also summarized through a retrospective literature review. Immunohistochemical staining is critical in the diagnosis of gastric metastasis from MM of the external ear. This disease often requires a multidisciplinary treatment approach, including surgery, targeted therapy and immunotherapy. The present study provides some genetic information about this rare disease and discusses appropriate treatment strategies. The findings of the present study suggests that the surgical margin size, tumor histological type and number of genetic aberrations may be closely associated with metastasis potential, therapeutic efficacy and patient outcome.