Primary Jejunal Melanoma Presenting as Widespread Metastases: Clinicopathological and Embryological Perspectives-A Case Report.

Primary malignant melanoma of the small intestine is an exceptionally rare and diagnostically challenging condition, largely due to the predominance of metastatic involvement in the gastrointestinal (GI) tract. We report the case of a 71-year-old male presenting with a large, pigmented jejunal mass accompanied by multiple distant metastases in the liver, adrenal glands, and lungs. Histopathological and immunohistochemical analyses performed on the jejunal mass confirmed the diagnosis of malignant melanoma. Although systemic metastases were present, thorough clinical examination revealed no evidence of cutaneous, ocular, or mucosal primary lesions elsewhere, supporting the jejunum as the primary mucosal site of origin. This report discusses the embryological background, diagnostic challenges, and clinical significance of this rare entity. This case highlights that primary small bowel melanoma, although extremely rare, should be considered in patients presenting with intestinal lesions and disseminated metastases in the absence of an identifiable cutaneous primary lesion.