Clin Endosc.  2016 Jul;49(4):391-394. 10.5946/ce.2015.126.

Melanocytic Nevus on the Rectal Mucosa Removed Using Endoscopic Submucosal Dissection

• Kim SM
• Shin YJ
• Sim JS
• Lee BJ
• Joo MK
• Park JJ
• Bak YT

• KMID: 2348261
• DOI: http://doi.org/10.5946/ce.2015.126

Abstract

Melanocytic nevus is the benign proliferation of melanocytes. The most common location of melanocytic nevus is the skin of the extremities; however, there are few case reports of melanocytic nevus at the rectal mucosa. No prior case of malignant melanoma from melanocytic nevus at the rectal mucosa has been reported; therefore, it is unclear whether resection should be performed or close observation is sufficient. However, the potential malignant transformation of melanocytic nevus should be considered, including melanocytic nevus on the rectum. Melanocytic nevus of the skin can be removed by surgical excision; however, due to rare incidence on the mucosa of the gastrointestinal tract, the optimal treatment for rectal melanocytic nevus remains controversial. Here, we report the first case of melanocytic nevus on the rectal mucosa that was removed by endoscopic submucosal dissection. This case report provides useful information about the optimal management of rectal melanocytic nevus.

Keyword

Nevus, pigmented; Melanoma; Endoscopic submucosal dissection

MeSH Terms

Extremities
Gastrointestinal Tract
Incidence
Melanocytes
Melanoma
Mucous Membrane*
Nevus, Pigmented*
Rectum
Skin

Figure

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  Fig. 1. Endoscopic finding of rectal melanocytic nevus. A 1.0×0.8 cm hyperpigmented and slightly

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  Fig. 2. Histopathological findings of endoscopic biopsy tissue. (A) The sample is composed of many melanocytes and brown pigmentation without malignant cells (H&E stain, ×40). (B) The Ki-67 labeling index of the specimen is <1% (×200).

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  Fig. 3. Endoscopic submucosal dissection of melanocytic nevus of the rectum. (A) A rectal melanocytic nevus is visible on the far-distal rectum. (B) A submucosal injection is performed using epinephrine-indigo carmine-saline solution. (C) A mucosal incision around the lesion is made using a needle knife. (D, E) The submucosal dissection is performed using an insulated-tip knife. (F) The rectal melanocytic nevus is completely removed without major complications.

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  Fig. 4. Histopathological findings of the resected specimen. (A) The gross findings of the specimen indicate that the lesion is 0.7×0.7 cm. (B) The nevus involves the submucosa of the anorectal junction (H&E stain, ×12.5). (C) The resected lesion is composed of many melanocytes without malignant cells. Almost all of the cells include brown pigmentation (H&E stain, ×400). (D) The lesion is positive for S-100 (×100).

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