Authors M. DE KEUKELAERE (1), K. VAN HOEVE (2), I. HOFFMAN (2) / [1] Imelda Hospital, Bonheiden, Belgium, pediatrics, [2] Universitair Ziekenhuis Leuven, , Belgium, pediatric gastroenterology Background: We describe a child with protein losing enteropathy as presentation of collagenous duodenitis and eosinophilic gastroenteritis. Although, both diseases are rare in children, the combination is extremely rare. Summary: A four-year-old girl presented at the emergency department with non-bloody diarrhea for two months and progressive oedema with an albumin of 16g/dl. The diagnosis of a protein losing enteropathy was made. Extensive investigations withheld only an infectious cause of the protein losing enteropathy (co-infection of acute cytomegalovirus and adenovirus). Despite supportive treatment with albumin infusions, no spontaneous recovery was seen. Therefore, a new endoscopic work-up was performed. Duodenal biopsies revealed collagen deposition, in association of a high number of eosinophils and mast cells throughout different parts of the gastrointestinal tract. The diagnosis of a diffuse eosinophilic gastroenteritis and collagenous duodenitis was made. Collagenous gastroenteritis can affect multiple parts of the gastrointestinal system. Clinical presentation varies widely, ranging from abdominal pain and diarrhea to more severe clinical picture with malabsorption and protein losing enteropathy. Typical histopathological findings are: collagen band thickness > 10µm in the subepithelial mucosa, increased inflammatory cell infiltration in the lamina propria, and surface epithelial damage (1-2). The underlying pathogenesis is unknown. Several hypothesis are postulated to describe the collagen deposition: (1) as a result of chronic inflammation and/or an autoimmune mechanism, (2) abnormalities of peri-cryptal fibroblast sheath or proteins, and (3) fibrinogen leakage with increased collagen replacement due to primary vascular abnormality with increased vascular permeability (3-4). The immune-mediated hypothesis is the most popular theory because of frequent association with autoimmune disorders and overexpression of HLA-DR by epithelial cells and CD25-positive cells in the lamina propria as a sign of continue inflammation (5-7). These activated immune cells will produce cytokines and growth factors that in turn stimulate the extracellular matrix-producing myofibroblasts. It is presumed that a luminal agent (such as infections or toxins), or allergic reactions to environmental or dietary antigens may act as a trigger for chronic inflammation and will initiate this fibroinflammatory condition. As collagenous gastroenteritis is a scarce disorder, there is no standardized treatment yet. Exclusive amino acid-based diet and oral antihistamine were started to treat the underlying food allergy. In addition, high doses of proton pomp inhibitor (2 mg/kg/day) were added to achieve an anti-inflammatory effect and iron deficient anaemia was supplemented. Clinical improvement was seen rapidly, with normalization of serum albumin within 1.5 weeks, and this remained stable during follow-up without extra albumin infusion. We do not have a histological correlation yet, but literature shows that it takes months, even years before histological improvement is seen. Conclusion: As collagenous gastroenteritis in children is a rare entity, little is known about the triggers, natural course and most effective treatment. In our case, the protein losing enteropathy was caused by a collagenous duodenitis, most likely triggered by an underlying food allergy as represented with infiltration of eosinophils and mast cells in the gastrointestinal tract. Although, this condition is extremely rare, gastroenterologists and pathologists need to be aware of this condition to enable accurate diagnosis, so that appropriate therapy could be started in a timely manner. As more cases will be reported, we will hopefully develop more insight in this disease.
