Colonic lymphoid hyperplasia in melanosis coli

We describe the case of a patient with Rett syndrome, a syndrome characteri zed by progressive infant encephalopathy, developmental delay, dementia, au tism, ataxia, microcephaly, spastic paraparesis, and autonomic neuropathy w ith constipation. At colonoscopy, multiple foci of tiny white, sessile, pol ypoid lesions were seen throughout the colon and rectum, mimicking the appe arances of small hyperplastic or adenomatous polyps, associated with genera lized melanosis coli. This is the first case to our knowledge describing me lanosis coli in a patient with Rett syndrome. As melanosis pigment depositi on is characteristically not seen in lymphoid tissue, the lymphoid tissue w as identifiable at endoscopy as multiple white nodules mimicking generalize d colonic polyposis throughout the colon. We discuss the likely mechanisms of lymphoid hyperplasia and coexistent melanosis coli in Rett syndrome.