Paneth Cell Metaplasia in Pediatric Distal Colon Biopsies: Incidental Finding or a Predictor of Inflammatory Bowel Disease (IBD)?

Paneth cells are normally found in the small intestine and its presence in the distal colon is referred to as Paneth cell metaplasia (PCM). PCM in children is commonly seen in patients with newly diagnosed inflammatory bowel disease (IBD) and in unremarkable rectal mucosa in patients with chronic constipation. However, the significance of PCM in children in a consecutive clinical cohort remains unknown. All distal colon biopsies obtained from pediatric patients during a 6-month period were reviewed for PCM. PCM was identified in 32 of 188 cases (17%), median age of 14 years (range: 3-17), and 75% were male. The most common location for PCM was the descending colon, and abdominal pain was the most common indication for colonoscopy. Nineteen cases (59%) had at least 1 additional feature of chronic mucosal injury and 4 patients (12%) had non-necrotizing mucosal granulomas. At the time of the biopsy, only 9 patients (28.1%) had a clinical diagnosis of IBD (4 Crohn disease [CD] and 5 ulcerative colitis [UC]) but at the end of the follow-up period, most patients (87.5%) had a diagnosis of IBD (15 CD and 13 UC). Six patients with PCM had a normal colonoscopy and an otherwise normal histology and of these 3 developed IBD. Our findings suggest a strong association with PCM in the distal colon in pediatric patients and the subsequent development of IBD. This highlights the importance of identifying PCM in distal colon biopsies.