Hemosiderin deposition in the lamina propria of the septum: a histological feature of type I intestinal atresia.

BACKGROUND: We investigated and compared the potential histological characteristics of the septum arising from type I intestinal atresia (IA) with those of the normal intestinal wall. METHODS: This retrospective descriptive histological study included neonates with surgically and pathologically confirmed type I intestinal atresia treated between September 2016 and December 2021. Septal tissue and paired adjacent proximal intestinal wall tissue were collected during surgical resection. Serial paraffin sections were examined using hematoxylin and eosin staining, Masson's trichrome staining, and Prussian blue staining to compare mucosal architecture, erythrocyte extravasation, and hemosiderin deposition. RESULTS: In total, eight neonates were diagnosed with type I IA based on observation during surgery and postoperative pathological diagnosis. The topographical areas in all sections showed that both the septum and normal control tissues had typical lamina propria (LP) in the mucosa. H&E staining and Masson's trichrome staining indicated aggregated hemoglobin in the LP of the mucosa in the septum but not in the normal intestinal wall, suggesting that potential hemorrhage within the LP of septum mucosa occurred during the formation of IA. Prussian blue staining further demonstrated that positive particles were deposited in both the LP and part of the submucosa of the septa; no such sign was noted in the normal intestinal wall. CONCLUSION: Hemosiderin deposition in the LP, caused by intraorganizational hemorrhage in LP in the septa, is a discernible histological characteristic of the septum. This characteristic provides histological evidence to distinguish septum arising from IA from the normal intestinal wall.