Congenital Microvillous Atrophy, Report of Two Consecutive Siblings with Complete Histologic, Immunohistochemical and Detailed Electron Microscopic Studies, First Report from Iran

Abstract

Background: Microvillous inclusion disease(MVD) or microvillous atrophy disorder is a congenital disorder of the small intestinal epithelial cells that presents with persistent and severe diarrhea and it is characterized by enterocytes abnormalities. The diarrhea starts in the first 72 hours of life(early onset form) or in 6 to 8 weeks after birth(late onset). Late onset cases were appeared to have a better prognosis. To our experiment, this disease is very rare in Iran and it is yet unreported, so we decided to report two consecutive siblings with the same disease from Iran. Case Presentation: Two siblings were born to healthy parents. Parents were cousins. The mother had no complications during her pregnancy. Family history was negative for such diseases. The boys were born by cesarean section at the age of 38 and 34 respectively (second boy came after one and half a year). The first child who died at two months of age had respiratory distress shortly after birth; as a result, surfactant therapy was recommended for him. Both siblings were hospitalized due to severe diarrhea starting shortly after breast feeding. The frequency of diarrhea in both cases was 10 to 17 times per day and their stools were loose and green. The first child was under antibiotic therapy since early life and received Scholl solution for one day with diagnosis of renal tubular acidosis which was discontinued when diarrhea got worse due to this treatment. There were no other abnormalities in physical examinations. Laboratory data revealed an osmotic diarrhea; no blood or leukocytes were seen in his stool. The first child's endoscopy was performed 50 days after his birth. Flat villi were seen in duodenum by endoscopy and several biopsies were taken. The second child underwent endoscopy at 10 days of age, but biopsy resulted in intestinal perforation, so laparotomy was performed and another full thickness biopsy of small intestine was taken. Histological studies of both siblings revealed duodenal mucosa with complete flattening of villi(total villous atrophy). Superficial lining cells showed atrophy. Crypts showed no hyperplasia, however, it showed distortion and difference in size. By PAS staining and CD10 staining, a poorly developed brush border and typical inclusions were seen in apical boarder of enterocytes. Electron microscopy was performed for the second case and showed microvillous involution and inclusions in the apical part of the epithelial cells. Conclusion: Although congenital microvillous atrophy is a rare disorder with poor prognosis, it must be taken seriously if an infant has severe and persistent secretory diarrhea, especially after discovery of new therapies such as intestinal transplantation, somatostatin analog and epidermal growth factor, which improve prognosis of these patients and gives us hope for treatment of this disease.