Pneumatosis cystoides intestinalis lesions changing into yellowish plaque-like elastosis lesions during healing

Pneumatosis cystoides intestinalis (PCI) is a rare disease characterized by multiple gas-filled cysts in the intestinal wall. The majority of patients with PCI are asymptomatic and have a benign clinical course without treatment. Regular colonoscopic follow-up is not always clinically necessary for PCI; therefore, whether all patients with PCI eventually achieve complete endoscopic resolution remains unclear. We herein present the details of an asymptomatic 58-year-old man diagnosed with PCI in the right colon in 2011 by colonoscopy. We followed him using colonoscopy for 8 years without treatment. The PCI lesions gradually changed into multiple flat yellowish plaque-like lesions, and biopsies revealed that these were elastosis, which is a very rare pathological finding in the colon. To our knowledge, only two reports discuss morphological or histological changes similar to those of PCI. Because the development of yellowish plaque-like lesions histologically representing elastosis associated with PCI is an unrecognized entity, we herein discuss its clinical features, endoscopic findings, and histological findings with a literature review.