Ockham’s razor defeated: about two atypical cases of hemolytic uremic syndrome

BMC Nephrology

Lara Zafrani¹  Alice Brehon²  Patricia Senet²  Patricia Mariani³  David Buob⁴  Véronique Frémeaux-Bacchi⁵  Chloe Schwarz⁶  Cyril Mousseaux⁶  Eric Rondeau⁶  Cédric Rafat⁶  Yosu Luque⁶  Inna Mohamadou⁶ 

[1] Service de Médecine Intensive et Réanimation, hôpital Saint Louis;Service de dermatologie, hôpital Tenon;Service de microbiologie, hôpital Robert Debré;Service d’anatomopathologie, hôpital Tenon;Service d’immunologie, Hôpital Européen Georges Pompidou;Service d’urgences néphrologiques et transplantation rénale, hôpital Tenon;

关键词: HUS;    STEC;    Physiopathology;    aHUS;    Parvovirus B19;    Case report;   

DOI  :  10.1186/s12882-020-01926-2

来源: DOAJ

【 摘 要 】

Abstract Background Medical investigation is a favorite application of Ockham’s razor, in virtue of which when presented with competing hypotheses, the solution with the fewest assumptions should be privileged. Hemolytic uremic syndrome (HUS) encompasses diseases with distinct pathological mechanisms, such as HUS due to shiga-like toxin-producing bacteria (STEC-HUS) and atypical HUS, linked to defects in the alternate complement pathway. Other etiologies such as Parvovirus B19 infection are exceptional. All these causes are rare to such extent that we usually consider them mutually exclusive. We report here two cases of HUS that could be traced to multiple causes. Cases presentation Case 1 presented as vomiting and diarrhea. All biological characteristics of HUS were present. STEC was found in stool (by PCR and culture). After initial remission, a recurrence occurred and patient was started on Eculizumab. Genetic analysis revealed the heterozygous presence of a CFHR1/CFH hybrid gene. The issue was favorable under treatment. In case 2, HUS presented as fever, vomiting and purpura of the lower limbs. Skin lesions and erythroblastopenia led to suspect Parvovirus B19 primo-infection, which was confirmed by peripheral blood and medullar PCR. Concurrently, stool culture and PCR revealed the presence of STEC. Evolution showed spontaneous recovery. Conclusions Both cases defy Ockham’s razor in the sense that multiple causes could be traced to a single outcome; furthermore, they invite us to reflect on the physiopathology of HUS as they question the classical distinction between STEC-HUS and atypical HUS. We propose a two-hit mechanism model leading to HUS. Indeed, in case 1, HUS unfolded as a result of the synergistic interaction between an infectious trigger and a genetic predisposition. In case 2 however, it is the simultaneous occurrence of two infectious triggers that led to HUS. In dissent from Ockham’s razor, an exceptional disease such as HUS may stem from the sequential occurrence or co-occurrence of several rare conditions.

【 授权许可】

Unknown