Deep Beneath The Skin: A Rare Case Of Upper Gi Bleeding

INTRODUCTION: The gastrointestinal (GI) tract is a common site of metastases for oculocutaneous melanoma. Very rarely GI melanoma is observed without the identification of a primary oculocutaneous lesion, termed melanoma of unknown primary (MUP). There are several hypotheses which could explain this phenomenon, including regression from primary lesion or nodal melanocytes which mutates into melanoma. Drastic presentations of this rare diagnosis are uncommon, especially with GI bleeding. We present a successfully treated patient with MUP that presented as upper GI bleeding. CASE DESCRIPTION/METHODS: Case of an 88-year-old male with vitiligo who presented with a four-day history of dark tarry stools. He also reported a 4-month history of postprandial epigastric abdominal pain and unintentional weight loss. He denied odynophagia, dysphagia or hematemesis. Physical examination with no cutaneous lesions. Abdominal-Pelvic CT showed an intraluminal mass within the stomach cardia, periaortic lymphadenopathy near the distal esophagus and bilateral adrenal masses. Upper GI tract endoscopy revealed a large subepithelial ulcerated mass at cardia with biopsies negative for malignant cells. PET CT scan showed hypermetabolic lesion in the cardia, evidence of metastatic disease to peritoneum, adrenal glands, and extensive lymphadenopathy. Left supraclavicular lymph node biopsy reactive with triple positive stain for SOX10, HMB-45, Melan A and tyrosinase consistent with metastatic malignant melanoma. Treatment was initiated with Nivolumab. Follow up abdominopelvic CT scan with soft tissue mass at cardia no longer visualized, marked decrease in size of thoracic metastatic lymphadenopathy as well decrease size of bilateral adrenal metastatic lesions. DISCUSSION: While MUP is an accepted pathology for GI melanomas with no identifiable oculocutaneous lesions, primary GI melanoma remains much more controversial. No standard guidelines have been developed to differentiate between primary and secondary GI melanoma. In our case, the identification of multiple lesions in different organ systems made his GI malignancy more likely to be MUP than a primary melanoma. This case demonstrates the importance of a broad differential diagnosis in cases of upper GI bleeding and the relevance of a thorough physical examination for cases of MUP. Although common consequences of melanoma are known by most physicians, we should be aware of this clinical presentation as early diagnosis can result in providing the correct treatment.Figure 1.: This Abdominopelvic CT Scan shows intraluminal mass in stomach cardia of 4cm.Figure 2.: Upper GI Endoscopy showing mass in cardia with central ulceration.Figure 3.: PET CT Scan shows hypermetabolic lesion in gastric cardia measures 4.6cm AP x 4.4cmTR x 3.5cm CC. Large hypermetabolic lesions with photopenic centers and multiple nodules with increased uptake.