Contribution and limits of CD157 in the detection of the paroxysmal nocturnal hemoglobinuria clone: a case report

Flow cytometry is the gold standard for the detection of paroxysmal nocturnal hemoglobinuria (PNH) clones. Several antibody panels have been used with varying sensitivities and specificities. The CD157 is one of the glycosylphosphatidylinositol-anchored molecules tested and widely used. The CD157 deficiency is rare. We report a case of an isolated CD157 deficiency discovered during the search for the PNH clone in a patient with a plastic anemia. The interpretation of the results in this case poses a problem of false positive. We discuss how to deal with these difficulties encountered by the biologist, detailing the various possible causes. This observation also underlines the importance of following international guidelines before making the diagnosis of the PNH clone which has significant implications.