Published online Jul 6, 2019. doi: 10.12998/wjcc.v7.i13.1652
Peer-review started: March 2, 2019
First decision: March 29, 2019
Revised: April 15, 2019
Accepted: May 2, 2019
Article in press: May 2, 2019
Published online: July 6, 2019
Anorectal malignant melanoma (AMM) is a rare disorder with an extremely poor prognosis. Although there is currently no consensus on the treatment methods for AMM, surgical procedures have been the most common treatment methods used until now. We recently encountered a case of AMM that we diagnosed using endoscopic submucosal dissection (ESD). To our knowledge, this is the first case of ESD for AMM, suggesting that ESD can potentially be a diagnostic and treatment method for AMM.
A 77-year-old woman visited our hospital with a chief complaint of anal bleeding and a palpable rectal mass. Colonoscopy revealed a 20-mm protruded lesion in the lower rectum. After obtaining biopsy specimens from the lesion, although a malignant rectal tumor was suspected, a definitive diagnosis was not made. Endoscopic ultrasonography revealed tumor invasion into the submucosal layer but not the muscular layer. Therefore, we performed an excisional biopsy using ESD. Immunohistochemical examination of the ESD-resected specimen revealed tumor cells positive for Human Melanin Black-45, Melan-A, and S-100. Moreover, the tumor cells lacked melanin pigment; thus, a diagnosis of amelanotic AMM was made. Although the AMM had massively invaded the submucosal layer and both lymphatic and venous invasion were present, we closely monitored the patient without any additional therapy on the basis of her request. Six months after ESD, local recurrence was detected, and the patient consented to wide local excision.
It is suggested that ESD is a potential diagnostic and treatment method for AMM.
Core tip: For anorectal malignant melanoma (AMM), surgical procedures such as abdominoperineal resection and wide local excision have been the most common treatment methods used until now. We recently encountered a case in which endoscopic submucosal dissection (ESD) was used for an excisional biopsy of AMM. ESD may be effective for an early and accurate AMM diagnosis because the ESD-resected specimen could provide adequate pathological findings. In addition, as the ESD technique can yield a high en bloc resection rate, ESD may effectively treat early-stage AMM. Thus, it is suggested that ESD is a potential diagnostic and treatment method for AMM.