Melanosis coli is an infrequent disorder of the large intestine with a deposition of melanin or melanin-like pigment. The most important factor in the etiology of the disease is a prolonged colonic stasis with a long term administration of anthracene laxatives. A restoration to regular bowel habit and an interruption of anthracene laxatives result in a complete disappearance of the pigmentation. Melanosis coli by itself is usually asymptomatic.
A patient with melanosis coli presenting here developed recurrent melena and severe abdominal pain. G.O., a 58-year-old man, was admitted to the hospital in November, 1964, because of severe abdominal pain and several episodes of melena. Suffering from habitual constipation, he took rhubarb for many years. Physical examination revealed a chronically ill man who had a tender resistance in the right lower quadrant. Laboratory findings showed anemia (Hb 10.8g; dl). No pathogenic organisms, including tubercle bacillus, were detected in the feces. A X-ray finding with barium enema and air contrast examination of the colon showed an irregular mucosal folds from the end of the ileum to the caecum. No narrowing and shortening of the bowel were seen.
An administration of beta-methazone was showed no beneficial effect. ACTH was remarkably effective to relieve the symptoms, following the decrease of the doses, however, the symptoms reappeared and surgical treatment was necessitated.
At the operation, no ulcer or erosion was seen on the surface of the colon, and a number of miliary-sized, dark brown spots were observed from the caecum to the transverse colon. The pigments were identified as melanin by histochemical examination.
Considering that melanosis coli by itself usually has no hazard to health, this case with recurrent severe melena is extremely rare. Reviewing literatures, only one case with similar symptoms was reported by Hillmand in 1952.
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