Title : Rectal malignant melanoma: A second primary malignancy in a filipino adult male- A case report
Abstract:
Malignant melanoma is most commonly found on the skin and rarely occurs in the the rectal region. We report a case of a 77-year-old Filipino adult presenting with rectal bleeding for three weeks. He underwent sigmoidoscopy that showed thrombosed hemorrhoids; however, subsequent surgical excision biopsy histopathology and immunohistochemistry revealed features compatible with malignant melanoma (HMB45, Melan A, and Cytokeratin positive; CDX2 negative). Staging workup done, including abdominal magnetic resonance imaging (MRI) with IV contrast and chest computed tomography (CT), showed distant metastases. He was then started on pembrolizumab but follow up imagings showed recurrence of the rectal melanoma and progression of metastases. Due to this, treatment was shifted to imatinib. This case illustrates that rectal melanoma can be misdiagnosed as hemorrhoids. It also shows that it is an aggressive disease; therefore multidisciplinary management is crucial to yield the best possible outcome, despite its poor prognosis. Such as in this case, using immunotherapy and targeted therapy still have inconsistent outcomes, thus, further studies should be pursued.
Audience Take-Away:
- This case report will raise further awareness and increase clinical suspicion among physicians, especially gastroenterologists regarding rectal malignant melanoma
- The audience will be able to learn how to recognize and diagnose rectal malignant melanoma
- They will also add knowledge to the audience and other faculty regarding the management of rectal malignant melanoma, which has yet to be established
