P1291 - A Rare Case of Rapidly Progressive Stage IV Rectal Melanoma Disguised as a Hemorrhoid

Brittney Shupp, DO¹, Mina Aiad, DO², Hammad Liaquat, MD³, Janak Bahirwani, MD¹, Lisa Stoll, MD², Diana Jaiyeola, MD^3
1St. Luke's University Health Network, Bethlehem, PA; ²St. Luke's University Hospital, Bethlehem, PA; ³St. Luke's University Health Network, Fountain Hill, PA

Introduction: Rectal melanoma is a rare cancer that often masquerades itself as a hemorrhoid. While hemorrhoids are common and benign, rectal melanoma is aggressive and often metastatic at diagnosis with a median survival of 24 months. We present an unfortunate case of rectal melanoma which rapidly progressed to widespread metastatic disease.

Case Description/Methods: 61-year-old male presented with epigastric pain and melena. A colonoscopy was completed months earlier demonstrating diverticulosis and hemorrhoids. On presentation, the patient was afebrile with stable vitals and epigastric tenderness. Labs showed: hemoglobin 11.0 g/dL, sodium 136 mmol/L, WBC 13.97 thousand/uL, INR 1.10, lipase 58 u/L, and normal LFTs. CT abdomen/pelvis revealed innumerable metastatic liver and lung lesions and a large 4.6 x 10.2 x 8.5 cm mass in the gastrohepatic region infiltrating into the liver and intrahepatic IVC along with perihepatic and pelvis ascites. EGD was completed and showed nodular mucosa in the stomach, but biopsies were negative. IR guided liver biopsy was performed and revealed malignant melanoma. Subsequently the patient had a hemoglobin drop and was found to have a subcapsular hematoma requiring IR embolization. Patient was later discharged with instructions to follow up with medical oncology. Two weeks later, the patient presented with generalized abdominal pain, distension, and hematochezia. CT abdomen/pelvis revealed rapid progression of the metastatic tumor in the liver, new omental metastasis, and a probable anorectal metastatic lesion. A flexible sigmoidoscopy was performed and discovered a fungating mass above the anorectal junction covering 25% of the circumference. Biopsies were taken and pathology was consistent with rectal melanoma. Shortly after, the patient had a rapid decline with multiorgan failure, continued rectal bleeding, and worsening hemorrhagic ascites. The patient was transitioned to comfort care and died less than one month after his initial presentation.

Discussion: Anorectal melanomas account for 0.4-1.6% of melanomas and 1-2% of lower gastrointestinal malignancies. Of these cases, majority are in the anus or anal canal and 35% occur in the rectum, above the dentate line. Diagnosis is often delayed or missed as cases are often amelanotic and diagnosed as a rectal polyp or hemorrhoid initially leading to delayed diagnosis and a 10% 5-year survival rate. Therefore, this case is a rare case that highlights both the aggressive and masquerading nature of rectal melanoma.


Figure: Flexible sigmoidoscopy demonstrating a fungating, friable, non-obstructive mass above the anorectal junction covering approximately 25% of the circumference (A,B). CT abdomen/pelvis showing innumerable metastatic liver lesions (red arrow, C) and a large subcapsular hematoma along the undersurface of the left hepatic lobe measuring 13.8 x 9.4 cm (orange arrow, C). Large 4.6 x 10.2 x 8.5 cm mass in the gastrohepatic region infiltrating into the liver and intrahepatic IVC (green arrows, C). Focal soft tissue prominence involving the anus eccentric to the right suspicious for metastatic disease along with omental thickening and modularity (blue arrow, D). Liver pathology demonstrating pleomorphic epithelioid cells with prominent nucleoli and melanin pigment (yellow arrows, 40X magnification) (E). Rectal mass biopsy pathology with SOX10 nuclear expression confirming the diagnosis of melanoma (20X magnification) (F).


Disclosures:
Brittney Shupp indicated no relevant financial relationships.
Mina Aiad indicated no relevant financial relationships.
Hammad Liaquat indicated no relevant financial relationships.
Janak Bahirwani indicated no relevant financial relationships.
Lisa Stoll indicated no relevant financial relationships.
Diana Jaiyeola indicated no relevant financial relationships.


Brittney Shupp, DO¹, Mina Aiad, DO², Hammad Liaquat, MD³, Janak Bahirwani, MD¹, Lisa Stoll, MD², Diana Jaiyeola, MD³. P1291 - A Rare Case of Rapidly Progressive Stage IV Rectal Melanoma Disguised as a Hemorrhoid, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.