What diagnosis is characterized by a microcolon?

Cystic fibrosis is characterized by the presence of a microcolon, specifically in the context of intestinal obstruction due to thick, viscous meconium that blocks the intestines. In infants with cystic fibrosis, the meconium can be so thick that it doesn't move through the intestines as it should, leading to an underdeveloped or decreased size of the colon, known as microcolon. This finding can be particularly evident in imaging studies, where the colon appears smaller than normal.

In contrast, intestinal atresia typically presents with a dilated proximal segment of the bowel and a normal-sized distal bowel. Necrotizing enterocolitis involves bowel necrosis, often accompanied by pneumatosis intestinalis, not microcolon. Appendicitis commonly presents with a normal bowel size, and while it can lead to complications, it is not associated with the radiological finding of microcolon. Hence, cystic fibrosis is the diagnosis that is most closely associated with the characteristic of a microcolon.