Nassau University Medical Center East Meadow, NY, United States
Charudatta Wankhade, MD, Bobby Jacob, MD, Kristen L. Farraj, DO, Shino Prasandhan, MD, Pranay Srivastava, MD, Kevin Yeroushalmi, MD, Deepthi Kagolanu, MD, Kaleem Rizvon, MD Nassau University Medical Center, East Meadow, NY
Introduction: Melanomas within the gastrointestinal tract are usually metastatic in origin and primary melanomas of the gastrointestinal tract are relatively uncommon. We describe a patient that presented with rectal bleeding and a mass on a rectal exam. Colonoscopy followed by histopathological examination confirmed a diagnosis of malignant melanoma.
Case Description/Methods: A 67 year old Hispanic male with no significant past medical history was admitted for evaluation of rectal bleeding for the past 6 months. He never seeked medical attention. Review of the systems was positive for an unintentional weight loss of 20 pounds in the past 6 months. Family and social history were not significant. Digital rectal exam was positive for blood and a palpable mass but the remainder of the physical examination was unremarkable.
Laboratory work was significant for microcytic anemia with hemoglobin of 9. CT scan was suggestive of an intraluminal 5.2 cm soft tissue mass in the distal sigmoid colon or rectum with surrounding inflammatory changes highly concerning for colon carcinoma and pelvic sidewall lymphadenopathy. Colonoscopy revealed a 6 cm ulcerated, friable, partially circumferential rectal mass. Biopsies revealed poorly differentiated neoplasm. Immunohistochemistry was positive for S-100, Melan-A and HMB-45 which is consistent with malignant melanoma. Patient underwent diverting colostomy and is currently being treated with ipilimumab/nivolumab chemotherapy.
Discussion: Melanoma without an identifiable cutaneous or mucosal primary make up only 1–3% of melanoma cases per year. Within the GI tract, the small bowel is most frequently involved, followed by stomach, colon and esophagus. Colonic melanomas mostly develop in the ascending colon (46.7%) followed by cecum (26.7%) and less frequently in the transverse (13.3%) and left colon (13.3%). Abdominal pain and weight loss are the most common presenting clinical symptoms, with bleeding, neurological deficit and palpable abdominal mass being less frequently reported. Patients may present with acute complications such as bleeding, perforation, intussusception, and obstruction that require urgent surgical intervention. Immunohistochemistry is central in diagnosing malignant melanoma with S-100 being more sensitive and Melan A, HMB-45 being more specific. Surgical resection has been shown to improve prognosis and adjuvant therapy, including radiation, chemotherapy, and immunotherapy, is utilized for residual disease or nodal metastasis as in our patient.
Figure: CT Images of colonic mass and local metastasis Rectal mass on colonoscopy Histopathology of mass with immuno-histochemistry (S 100, Melan A, HMB 45)
Disclosures: Charudatta Wankhade indicated no relevant financial relationships. Bobby Jacob indicated no relevant financial relationships. Kristen Farraj indicated no relevant financial relationships. Shino Prasandhan indicated no relevant financial relationships. Pranay Srivastava indicated no relevant financial relationships. Kevin Yeroushalmi indicated no relevant financial relationships. Deepthi Kagolanu indicated no relevant financial relationships. Kaleem Rizvon indicated no relevant financial relationships.
Charudatta Wankhade, MD, Bobby Jacob, MD, Kristen L. Farraj, DO, Shino Prasandhan, MD, Pranay Srivastava, MD, Kevin Yeroushalmi, MD, Deepthi Kagolanu, MD, Kaleem Rizvon, MD. P0286 - Common Presentation with an Uncommon Histology- a Rare Case of Malignant Melanoma of Colon, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.