THE PATHOLOGY OF INFANTILE HYPERTROPHIC PYLORIC-STENOSIS AFTER HEALING

Introduction: Infantile hypertrophic pyloric stenosis (IHPS) is a comm on surgical affection of unknown etiology. The muscular hypertrophy is known to resolve within a few months after pyloromyotomy (PM). The pa thology of IHPS has been studied extensively at the time of PM, but th e fate of the pylorus after heating remains unknown. Materials and Met hods: We had the rare opportunity to study two pyloric biopsy specimen s obtained 4 months and 2 years (respectively) after an uncomplicated PM for IHPS. They were compared with the initial specimen in one case, with 26 other specimens of IHPS, and with five normal controls. Immun ohistochemistry using the avidin-biotin complex (ABC) system was perfo rmed for S-100 and nerve growth factor receptor, as markers for the en teric nervous system, and for the tyrosine kinase receptor c-kit, as a marker for the interstitial cells of Cajal (pacemaker cells). NADPH-d iaphorase histochemistry was performed as a marker for the neuronal en zyme nitric oxide synthase, which produces the inhibitory neurotransmi tter nitric oxide. Results: In both cases of IHPS, after healing, the circular musculature was not hypertrophic. For all markers studied, th e distribution appeared similar to that in the normal pylorus. In cont rast, all specimens obtained at the time of PM displayed a severe redu ction of the different markets in the hypertrophic musculature. Discus sion: The pathological features observed in the circular layer in IHPS appear to resolve within a few months after PM. This suggests that th e involvement of the enteric nervous system in IHPS might be milder th an generally assumed. The etiology remains obscure, but our occasional observations may provide new insight into the pathophysiology of IHPS , and are in agreement with the excellent long-term clinical outcome f or IHPS. Copyright (C) 1996 by W.B. Saunders Company.