Recurrent Atypical Hemolytic Uremic Syndrome: A Masquerade of Antibody-Mediated Rejection?

Abstract

Atypical hemolytic uremic syndrome (aHUS) is a complement-mediated thrombotic microangiopathy (TMA) resulting from uncontrolled activation of the alternate complement pathway. It is necessary to distinguish a recurrent aHUS posttransplant from de novo aHUS, as the former is usually associated with complement abnormalities and has a poorer prognosis. Furthermore, COVID-19 is believed to unmask underlying complement defects triggering a relapse of aHUS. In this report, we present one such unique histologic presentation of recurrent TMA following a COVID-19 infection, which was not just a diagnostic challenge but could easily have been misdiagnosed as an antibody-mediated rejection.

Keywords

• antibody-mediated rejection
• atypical hemolytic uremic syndrome
• genetic testing
• thrombotic microangiopathy