Osmotic Tubulopathy and Acute Thrombotic Microangiopathy in a Kidney Transplant Recipient With a Breakthrough SARS-CoV-2 Infection.

Acute kidney injury is a known complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection for which many different pathophysiological processes have been reported. Here, we present a case of a 45-year-old kidney transplant recipient with a breakthrough SARS-CoV-2 infection complicated by an episode of acute kidney injury 26 months after transplant. She had minimal respiratory symptoms, pancytopenia, mild hematuria, and proteinuria. A kidney biopsy revealed acute thrombotic microangiopathy (TMA) as well as an osmotic tubulopathy. The TMA was favored to be secondary to the SARS-CoV-2 infection because other etiologies for TMA, such as acute calcineurin inhibitor toxicity and acute antibody-mediated rejection, were excluded. The osmotic tubulopathy was favored to be secondary to remdesivir therapy, specifically related to the sulfobutylether-ß-cyclodextrin solubilizing carrier agent used in its formulation. The patient's kidney function improved after resolution of the SARS-CoV-2 infection. This case illustrates a unique occurrence of kidney injury secondary to SARS-CoV-2 infection and anti-COVID-19 therapy.

Hypocomplementemic Urticarial Vasculitis Syndrome Masquerading as Systemic Lupus Erythematosus: A Case Report.

Introduction: Hypocomplementemic urticarial vasculitis syndrome (HUVS) is an infrequent immune complex-mediated condition characterized by nonpruritic urticarial lesions, low serum complement levels, and autoantibodies, associated with systemic manifestations like arthralgia/arthritis, angioedema, ocular inflammation with conjunctivitis, episcleritis, uveitis, renal, gastrointestinal, and pulmonary involvement. HUVS and systemic lupus erythematosus (SLE) overlap and the criteria for identifying HUVS as an entity distinct from SLE are lacking. Despite the diagnostic criteria established by Schwartz et al. [Curr Opin Rheumatol. 2014;26(5):502-9], differentiation from SLE is sometimes difficult as patients often also fulfill the classification criteria of the American College of Rheumatology (ACR). The prognosis of HUVS depends on the organ system involved. Lung disease results in significant morbidity and mortality and is made worse by smoking. Kidney involvement with glomerulonephritis may ultimately result in end-stage renal disease with the need for kidney transplant. Death may also occur due to acute laryngeal edema. Case Presentation: We pre-sent a case of a 40-year-old female who had a diagnosis of SLE, presented with severe odynophagia, was found to have an erythematous macular rash, and had acute kidney injury attributed to contrast-related injury and cardiorenal syndrome. After the resolution of the AKI, she continued to have hematuria and low-grade proteinuria that led to a kidney biopsy that aided in the diagnosis of HUVS. Discussion/Conclusion: Given the rarity of this disease and the difficulty in differentiating HUVS from other rheumatological diseases such as SLE, further accumulation of cases is necessary to understand the best diagnostic modality for this entity.