AB150. 72. Primary anorectal melanoma in an Irish female: a case report
Daniel Burke, Laura Finnegan, Niall Kennedy, Rishabh Sehgal, Myles Joyce
Background: Primary anorectal melanoma (AM) is an extremely rare and aggressive neoplasm. They tend to metastasize early with an overall 5-year survival of <20%. Diagnosing AM remains difficult due to non-specific symptomatology. It is not uncommon for the diagnosis to be made after treatment for presumed benign disease. Currently no consensus exists regarding optimum surgical management as no superior long-term survival benefit has been shown between abdominoperineal-resection (APR) and wide-local-excision (WLE). Adjuvant chemotherapy, interferon, and radiation may offer some benefit for advanced disease.
Methods: We describe a case of an ulcerated anorectal malignant melanoma in a 78-yr old Irish female.
Results: She presented with a 2-month history of anal prolapse, incontinence, intermittent bleeding per-rectum and altered bowel habit. She had a significant past history for transitional-cell-cancer requiring right nephroureterectomy/adjuvant radiotherapy, hyperthyroidism, osteoporosis, hypertension, hypercholesterolemia, left leg deep-venous-thromboembolism, steroid induced myopathy, and congestive-cardiac-failure. Physical examination revealed a pigmented area within the perianal area without palpable inguinal lymphadenopathy. Full colonoscopy demonstrated 25 mm × 21 mm × 17 mm non-obstructing mass in the anal-canal protruding externally at 12 o’clock. Histology confirmed an invasive ulcerative pT4b anorectal malignant melanoma positive for S100+ Melan-A. The patient was managed conservatively after being discussed in the multidisciplinary meeting given her advanced age and number of co-morbidities. She is currently on Pembrolizumab (Keytruda®) immunotherapy.
Conclusions: Management options for AM remain controversial as no survival advantage has been shown between APR and WLE. Chemo/radio/immune therapy have limited role for advanced disease. A high index of suspicion and prompt endoscopy + biopsy is essential for early diagnosis and improving survival.
Keywords: Primary anorectal melanoma; abdominoperineal-resection (APR); pembrolizumab
Cite this abstract as: Burke D, Finnegan L, Kennedy N, Sehgal R, Joyce M. Primary anorectal melanoma in an Irish female: a case report. Mesentery Peritoneum 2019;3:AB150.
