melanosis coli

Melanosis coli is a benign, reversible condition characterized by brown-to-black discoloration of the large intestine’s mucosal lining due to lipofuscin pigment deposition in the lamina propria.​

Causes

It arises primarily from long-term use of anthraquinone laxatives like senna or aloe, which damage colon cells, leading to apoptosis and macrophage uptake of lipofuscin (not true melanin, hence “pseudomelanosis coli”). Other factors may include chronic constipation or rare associations with NSAIDs or bowel diseases.​

Symptoms and Diagnosis

The condition is asymptomatic and typically discovered incidentally during colonoscopy, where the mucosa shows a characteristic spotted or tiger-stripe pigmentation. No treatment is needed, as it resolves after stopping laxatives.