Although melanotic pigmentation of the colon has been recognized for almost a century, there has been surprisingly little written on this subject from a clinical standpoint. In the course of routine sigmoidoscopic examinations, this striking type of discoloration is not infrequently seen. The color of the mucosa varies from buff to dark brown or black, the deeper shade being broken into small angular, polyhedral designs by fine netlike striae of lighter shade, either yellow or brown. These small fields vary in size between 2 and 10 mm. in diameter. Small pinhead yellow follicles are frequently seen, being more noticeable in the milder cases of melanosis. One of the earliest writers likened the appearance of the mucosa of the bowel to that of a toad's back.1 Others have compared the appearance to a snake, crocodile or tiger skin.2 To us the pigmentation suggests somewhat a cross section of nutmeg.
BOCKUS HL, WILLARD JH, BANK J. MELANOSIS COLITHE ETIOLOGIC SIGNIFICANCE OF THE ANTHRACENE LAXATIVES: A REPORT OF FORTY-ONE CASES. JAMA. 1933;101(1):1–6. doi:10.1001/jama.1933.02740260003001