Gastrointestinal Bleeding From Metastatic Non-Cutaneous Melanoma Identified in the Ileum

Abstract

Case Description: A 72-year-old male patient with a history of primary non-cutaneous melanoma of the mediastinum presented with 3 days of hematochezia. He denied abdominal pain, hematemesis, or melena. He had undergone resection of a mediastinal mass 3 years previously with pathology showing that it was non-cutaneous melanoma. He underwent adjuvant radiotherapy 8 months after the mass was resected. Surveillance PET/CTs showed no evidence of residual disease and did not show any GI lesions. On admission, he was hemodynamically stable with physical examination notable for bright red blood in the rectal vault. Labs showed hemoglobin around 6.4 g/dL (11.8 1 month previously). Colonoscopy revealed an unremarkable colon except for two small clots in the cecum. The ileum was intubated and at 35 cm from the ileocecal valve a friable, hemicircumferential mass was visualized. (Fig 1) It was biopsied, tattooed, and a hemoclip was placed to aide with localization. CT Enterography revealed a 5.1 cm ileal mass. (Fig 2) The pathology from the biopsies showed melanoma. (Fig 3A-C) The patient underwent palliative resection of the ileal mass and 20 cm of ileum. Pathology from the resection confirmed metastatic melanoma with lymphovascular invasion. (Fig 3D-F) Ultimately, he developed FDG-avid supraclavicular lymphadenopathy and is currently receiving pembrolizumab for metastatic non-cutaneous melanoma and has had a good response.Discussion: Non-cutaneous melanoma, particularily of the mediastinum, is a rare tumor that is derived from melanocytes, which originate from neural crest cells. They can arise from the mucosal surfaces including the respiratory tract, gastrointestinal tract, ocular mucosa, and in extremely rare cases from the remnants of neural crest cells such as the thymus. Melanoma is the most common tumor to metastasize to the GI tract. Though cases series examining bleeding rates from cutaneous melanoma have established high rates of bleeding with gastrointestinal metastasis (20%), data is limited for non-cutaneous melanoma. Surgical management is required in most symptomatic metastatic GI lesions given the risk of rebleeding or obstruction. Our case demonstrated the importance of considering gastrointestinal involvement even in patients with remote disease who present with clinical gastrointestinal bleeding. We also demonstrate the importance of intubating and maximally evaluating the ileum in patients with hematochezia without a clear colonic source.2003_A Figure 1. CT Enterography, axial image showing the 5.1 cm ileal mass with adjacent hemoclip.2003_B Figure 2. Endoscopic image of friable, nearly circumferential ileal mass.2003_C Figure 3. Histologic features of biopsy and resection specimens The biopsy (A-C) was entirely composed of epithelioid neoplasm. (A) Hematoxylin and eosin (H&E) stained section shows sheets and small nests of neoplastic cells with large, hyperchromatic nuclei, prominent nucleoli (green arrow heads) and abundant, occasionally eccentric cytoplasm. Scattered mitotic figures (green arrows) are present. Some cells contain refractile brown pigment in their cytoplasms. Immunohistochemical stains for HMB-45 (B) and SOX10 (C) show diffuse cytoplasmic and nuclear staining, respectively, confirming the melanocytic nature of the neoplasm. Subsequent ileocolectomy (D-F) specimen demonstrated a large, mostly amelanocytic mass. (D) The mass is located deeper to the muscularis mucosa (white arrow). (E) In multiple areas, nests of neoplastic cells are seen within the lymphatic spaces (red arrow). (F) H&E stained section demonstrates atypical cells with