Blue nevus of the colorectal mucosa.

The blue nevus is a well-described benign melanocytic proliferation that generally occurs on the skin. Infrequently, blue nevi are found on mucosal surfaces. The most common location for mucosal blue nevi is the oral mucosa, with reported cases in the sinonasal mucosa and genital tract, as well as in other locations. To our knowledge, blue nevi of the rectal mucosa have not been described. Here, we describe a case of blue nevus arising in the rectal mucosa. Blue nevi are benign melanocytic proliferations with the potential for malignant transformation and should be included in the differential diagnosis of pigmented mucosal lesions of the rectum.