Duodenal Malignant Melanoma：Primary and Metastatic

Background: Duodenal malignant melanoma is rare, and its early clinical symptoms are insidious, making it difficult to diagnose in its early stages. Methods We explored the clinicopathological characteristics of duodenal malignant melanomas and association with BRAF mutations. Hematoxylin and eosin staining, immunohistochemical marker detection, and BRAF V600E mutation inspection via Sanger sequencing for two clinical cases of duodenal malignant melanoma were performed. The relevant literature was reviewed, and the clinical pathology was analyzed. Results The two patients (a 63-year-old female [Patient 1] and a 54-year-old male [Patient 2]) experienced pain and discomfort in their upper abdomen; moreover, they had endoscopic space-occupying lesions in the second part of their duodenum and invasively growing solid sheets of round, oval, or polygonal microscopic atypical tumor. Additionally, one of them had skin malignant melanoma and pigmentation, whereas the other was positive for BRAF V600E mutation. Tumor cell immunohistochemical analysis detected Vim, HMB45, Melan-A, and S-100 positive expression. They both underwent surgical treatment; however, Patients 1 and 2 died after 1 and 28 months, respectively. Conclusion Primary and metastatic cases should be diagnosed through previous medical history analysis and detailed physical and auxiliary examinations. This would enable a diagnosis based on characteristic histomorphology and immunohistochemical markers. An early diagnosis and surgical treatment can prolong patient survival and the molecular inspection of BRAF mutations can guide follow-up treatment.