Atypical Case of Mucosal Malignant Melanoma

Abstract

Purpose: Malignant melanoma of the gastrointestinal mucosa in the absence of cutaneous lesions is very rare. We report an unusual case of primary malignant melanoma of the duodenal mucosa. A 38-year-old diabetic male presented with nausea, bilious vomiting and severe, colicky, epigastric pain for 3 days associated with worsening jaundice for 7 days. Proton pump inhibitors were started 3 months earlier for “heart burn”. Review of systems was positive for decreased appetite. Rest of the history was non contributory. Physical exam revealed stable vitals; scleral icterus and epigastric tenderness. Initial laboratory work up was significant for elevated total bilirubin, transaminases and alkaline phosphatase suggestive of obstructive jaundice. Computed Tomography scan of abdomen with contrast showed hepatic hilar lymphadenopathy and biliary obstruction. Endoscopic Retrograde Cholangiopancreatogram revealed ulcerated proximal duodenal mass with common bile duct (CBD) stricture. Pathology confirmed duodenal malignant melanoma with involvement of CBD. Comprehensive physical exam to rule out any cutaneous or retinal melanoma was negative. Extensive imaging with whole body positron emission tomography and magnetic resonance imaging of the brain did not reveal any other foci. Despite being on chemotherapy and radiotherapy patient rapidly deteriorated with extensive metastasis and expired within 8 months of diagnosis. This case illustrates that a high index of suspicion is warranted to diagnose mucosal malignant melanoma in a timely manner which can originate in esoteric locations and progress rapidly with significant mortality.