A novel segmental absence of intestinal musculature with small intestinal stenosis: a case report.

BACKGROUND: Segmental absence of intestinal musculature (SAIM) is a rare cause of intestinal obstruction and perforation due to partial or complete defects in the intestinal muscularis propria in neonates and is occasionally observed in adulthood.

CASE PRESENTATION: The first case of small intestinal stenosis derived from SAIM, which was difficult to differentiate from Crohn's disease (CD), is reported. A 4-year-old girl presented with abdominal pain, anemia, and a positive fecal occult blood test. She was initially diagnosed with CD and started on treatment. Because her gastrointestinal symptoms persisted, her previous pediatricians tried to carry out capsule endoscopy, but it was not possible because the patency capsule was retained. Therefore, she was referred to our institute and re-evaluated. The patency capsule examination was repeated to re-evaluate small intestinal passage, but it stagnated again. Abdominal ultrasonography showed a poorly deformable intestinal tract that narrowed rapidly from the dilated segment and had a thin wall with an irregular laminar structure. In addition, unlike the typical ultrasonic CD findings, the power Doppler signal enhancement at the intestinal wall and "creeping fat sign" were not found. The patient was referred for laparoscopic observation to pediatric surgeons, who confirmed a prominently dilated intestinal tract 40 cm proximal to the ileocecal valve, which was resected. Histopathological findings showed longitudinal muscle hypoplasia of the resected, dilated intestinal tract and fat replacement of the muscle layer. At the stenosis site, the muscle layer was fibrotic and showed incomplete muscle arrangement. Because of these findings, she was diagnosed with SAIM. After the surgical treatment, no gastrointestinal symptoms relapsed, and the fecal occult blood test has remained negative for 2 years. Moreover, 8 months after surgery, double-balloon endoscopy showed no abnormalities, such as a longitudinal ulcer and cobblestone appearance.

CONCLUSIONS: In the present case, SAIM involved not only intestinal ileus and perforation, but also small intestinal stenosis. Although no other reports have demonstrated the usefulness of abdominal ultrasonography for the diagnosis of SAIM, the present report suggests that ultrasonography may be useful for differentiating SAIM from CD by close observation of the area around the small intestinal stenosis.