Immunohistochemical findings in rectal duplication mimicking rectal prolapse.

Alimentary tract duplications represent rare anomalies, with only 5 % occurring in the rectum. The variety in clinical presentation may lead to a delay in diagnosis or to incorrect and multiple surgical procedures. We report the clinical, histological and immunohistochemical characteristics of a rectal duplication occurring in a 3-month-old male with an unusual clinical presentation. Using routine histology and immunohistochemistry, the rectal duplication showed the diffuse presence of gastric mucosa with a characteristic immunophenotype (i.e., diffuse cytokeratin 7 positivity and scattered chromogranin immunoreactivity). As far as we know, this is the first report showing an immunohistochemical differentiation pattern of gastric lining in a rectal duplication. Our results, showing the presence of gastric mucosa, are suggestive of a possible origin from the embryonic foregut.