Segmental congenital defect of the intestinal musculature

Segmental congenital defect of the intestinal musculature

Congenital focal absence of the muscular layer of the small intestine is considered a rare cause of intestinal obstruction or perforation in the newborn. Its aetiology and pathogenesis are unknown. The first case of spontaneous perforation secondary to congenital absence of the gastric musculature was described in 1943 by Herbut [1]. Subsequently descriptions of spontaneous perforation in the small intestine and the colon appeared. In 1943, Emanuel described for the first time segmental absence of the intestinal musculature as a new cause of intestinal obstruction [2].
Here we present a case report of perforation due to congenital defects of the intestinal musculature. A premature 3-month-old male infant developed two abdominal events (the first one at the age of 2 months). The clinical diagnosis in both cases was necrotizing enterocolitis. We describe the recent one. The surgical specimen contained 2 segments of ileum 5 and 3 cm in length. The minimum diameter was 0.8 cm and the maximum 1 cm. On gross examination in the midportion of the second fragment of the intestine, a focus of perforation with thin and congested mucosa around was observed. The remaining intestine appeared intact. Histological examination revealed multifocal partial or complete absence of the muscularis propria (Fig. 1-4). The mucosa of the bowel was well preserved with high villi covered by normal, cylindrical epithelium. Muscularis mucosa appeared within normal limits. The submucosa and serosa were oedematous and slightly infiltrated by lymphocytes and plasma cells. The mucosa and submucosa surrounding the perforation were congested, oedematous with mild leucocytic reaction in the serosa. No thrombotic phenomena were observed. It was concluded that necrotizing enterocolitis was not observed. Histological sections of different areas of the specimen showed several foci of muscular hyperplasia of the muscularis propria. The plexuses of Auerbach and Meissner were absent in regions of muscle loss (Fig. 4), but present in others and appeared well formed and situated.
Neonatal focal spontaneous perforations of the gastrointestinal tract with no evidence of necrotizing enterocolitis or mechanical obstruction is a known phenomenon [1, 3, 4]. In spite of numerous theories proposed in the past, the majority of these lesions continue to be reported as spontaneous perforation of unknown aetiology [4]. The histological picture is distinctive and quite different from that of necrotizing enterocolitis, which is characterized at the early stage by necrosis of the mucosa, intestinal haemorrhage, and occasionally thrombosed capillary loops in the villous cores. Transmural necrosis and varying degrees of intramural haemorrhage are seen in a more advanced process [1, 4]. In all cases described in the literature, the histology showed intact mucosa, absence of muscularis propria and minimal or absent inflammation [1-5]. However, there are some similarities in aetiology between two entities. Most cases with congenital intestinal muscular defect occurred in premature infants with low birth weight [3]. Alawadhi et al. [6], basing on embryogenesis, proposed two theories that suggested either failure of resorption of the small intestine diverticula or overresorption of muscle during regression of the omphalomesenteric duct [3, 6]. In reference to the theory of primary defect, the presence of occasionally remaining myenteric plexus in regions of muscle loss is of importance because plexus formation in the ileum occurs at about the sixth week of gestation and follows the formation of the muscle layers [3, 6, 7]. Not all authors agree that this is a congenital anomaly, and some believe ischemia to be the only etiological factor in cases of perforation [4, 5]. Although the role of ischemia in causing perforations is accepted by most authors, it is difficult to explain such extensive muscular damage while the mucosa, which should be much more sensitive to ischemia, remains intact [4]. Some authors postulate that ischemic injury occurring postnatally or perhaps during late foetal life causes injury to both the mucosa and the muscularis propria. Taking into account the different degree of regenerative capacity of mucosa and muscles, the mucosa might regenerate and the muscularis propria might not, resulting in total or partial absence of the musculature [3]. Why does muscularis mucosa remain intact then?
In summary, congenital defect of the intestinal musculature is rare and its aetiology is controversial. In our reported case we did not find any signs of unresorbed necrotic muscles or fibrotic tissue. Moreover, we observed absence of the myenteric plexus in the region of muscle loss with no signs of inflammation. In our opinion, this is an important argument against the theory of pre- or postnatal ischemic aetio­­­logy in our case.


References

1. Izraeli S, Freud E, Mor C, et al. Neonatal intestinal perforation due to congenital defect in the intestinal muscularis. Eur J Pediatr 1992; 151: 300-303.
2. Emanuel B, Gault B, Sanson J. Neonatal intestinal obstruction due to absence of intestinal musculature: A new entity. J Pediatr Surg 1967; 2: 332-335.
3. Huang S, Vacanti J, Kozakewich H. Segmental defect of the intestinal musculature of a newborn: evidence of acquired pathogenesis. J Pediatr Surg 1996; 31: 721-725.
4. Litwin A, Avidor I, Schujman E, et al. Neonatal intestinal perforation caused by congenital defects of the intestinal musculature. Am J Clin Pathol 1984; 81: 77-80.
5. Carroll RL. Absence of musculature of the distal ileum a cause of neonatal intestinal obstruction. J Pediatr Surg 1973; 8: 29-31.
6. Alawadhi A, Chou S, Carpenter B. Segmental agenesis of intestinal muscularis: A case report. J Pediatr Surg 1986; 24: 1089-1090.
7. Okamoto E, Ueda T. Embryogenesis of intramural ganglia of the gut and its relation to Hirschsprung’s disease. J Pediatr Surg 1967; 2: 437-443.


Address for correspondence

Monika Dzieniecka MD
Department of Clinical Pathomorphology
Research Institute Polish Mother’s Memorial Hospital
ul. Rzgowska 281/289
93-338 Łódź
phone +48 42 271 12 80
e-mail: chicamonika@yahoo.es