Atypical HUS in a Lung Transplant Recipient with Salmonellosis

Abstract

<h3>Introduction</h3> Thrombotic microangiopathy/Atypical HUS following lung transplantation is unusual. An unusual case of TMA with multiple possible etiologies, including infection, is presented. <h3>Case Report</h3> 64-year-old African American woman 2 years post right single lung transplant presented with shortness of breath, lethargy and diarrhea. Infectious work up revealed MRSA in BAL and Salmonella in stool by PCR. She was treated with Vancomycin and Levaquin. Her immunosuppression regimen consisted of prednisone, Tacrolimus and Mycophenolate. Tacrolimus levels were within normal range (5-8 ng/ml). The platelet count started to decline on day 5 of hospitalization, with a nadir of 74K. She was also noted to have worsening renal function with creatinine increasing. There was evidence of hemolytic anemia. ADAMTS-13 activity was normal. Renal Biopsy was performed: There were arteriolar and glomerular capillary thrombi associated with intimal edema and endothelial injury. Ischemic glomerular changes were notes as was acute tubular injury. The findings were interpreted as thrombotic microangiopathy. There was no evidence of myoglobin casts. Therapy included transitioning calcineurin inhibitor to Cyclosporine and continued antibiotic therapy. Due to rapid improvement of renal function, Plasmapheresis was not performed. <h3>Summary</h3> Atypical HUS is a very unusual cause of AKI in salmonellosis, felt to relate to S.Typhi virulence factors. Cases of CNI induced atypical HUS have also been reported in lung transplant recipients, with an annual incidence of 2.3%. Early recognition is important in regards to prognosis and survival. In summary, regardless of etiology, is vital to recognize clinical features of atypical HUS/TTP early in transplant recipients and to clinically evaluate for many possibly etiologic factors before directly attributing injury solely to CNI related endothelial injury, as documented in this clinical case.