PR Bleeding Due to Left Colon Blue Nevi: Rare Case Report

The blue nevus is a benign melanocytic proliferation that is typically a skin lesion [1]. The extra cutaneous blue nevi are infrequently seen, and few cases were reported in the mucosa of different organs. Gastrointestinal tract mucosa blue nevus specifically is extremely rare.

This is a case of a 37-year-old male who was on 20 mg/OD isotretinoin capsule for acne vulgaris treatment. The patient presented a few weeks after lower gastrointestinal tract bleeding that is containing blood clots following increasing isotretinoin dose to 40 mg/OD. The patient denied appetite change, weight loss, abdominal pain, dysphagia, rashes, fever, and rigor. There was no family history of colon cancer or inflammatory bowel disease. The rectal exam revealed a small external hemorrhoid and there were no fissures. There were no skin lesions. The ophthalmic exam was normal. The iron was mildly reduced measuring 10.7 umol/L and apart from that not another abnormal laboratory result. A contrast enhanced abdomen and pelvis CT scan was obtained demonstrating no colonic masses or diverticular disease. Thereafter, the patient was scheduled for a colonoscopy for further evaluation which was performed showing several descending and sigmoid colon hyperpigmented lesions. Biopsies were taken and the result was nonspecific colitis [Figures 1&2].

The blue nevus is a pigmented commonly encountered skin lesion. Involvement of mucosal surfaces, especially genitourinary tract, has been described. However, gastrointestinal tract mucosa blue nevus is an extremely rare finding. No consensus about the origin of blue nevus but the most commonly accepted theory is that it originates from migrating neural crest cells. The blue nevus has two histological variants, which are the common and the cellular types [2,3]. The common blue nevus predominantly affects young females, and it is commonly found in the extremities, hips and scalp while the cellular blue nevus usually affects older individuals, and it is commonly found in the sacrum. The cellular blue nevus has the tendency to be larger than the common blue nevus and it can grow up to 2 cm in size. Histologically, blue nevus has proliferating melanocytes in the dermis layer of skin. These melanocytes contain different amounts of melanin, and this is what gives them the characteristic blue color. They are usually benign lesions but the compound variant of blue nevus that involves dermo-epidermal junction has malignant potential [2]. On colonoscopy, blue nevus appears as superficial hyperpigmented area [4,5]. Blue rubber bleb nevus syndrome is a rare disease manifested by multiple skin and visceral organs venous malformations and hemangiomas. Those can be present at any age. The most common presentation is lower gastrointestinal tract bleeding with resultant iron deficiency anemia. This syndrome lesion appears as cavernous venous dilations with a thin wall of smooth muscle cells lined by endothelial cells under a microscope [6,7]. The management plan of gastrointestinal tract lesions is controversial and is determined mainly by the disease extent and severity. Whereas most of the patients with milddisease- form respond well to supportive therapy utilizing iron supplementation. However, surgical resection, endoscopic sclerosis and laser photocoagulation are all have been proposed for patients with severe bleeding [6].

Due to the rarity of its occurrence, the gastrointestinal tract blue nevus clinical course is not clearly well known [7]. The blue nevus is almost always exclusively a skin lesion, and it is apparently a benign abnormality, but it has the potential for malignant transformation. Therefore, the possibility of extra cutaneous blue nevus should be entertained.

None.

No conflict of interest.

1. Naziheh Assarzadegan, Kevan Salimian, Danielle Hutchings, Annika Lisbeth Windon, Lysandra Voltaggio, et al., (2021) Clinicopathological study of blue nevi of the gastrointestinal (GI) tract: first case series. J Clin Pathol 74(3): 167-170.
2. Jasbir Makker, Sailaja Sakam, Prasanthi Arety, Masooma Niazi, Bhavna Balar (2015) Rectal blue nevus: Case report of a rare entity and literature review. Pathology - Research and Practice 211(8): 625-627.
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