Pigment Nephropathy Mistaken for Complement-Mediated Thrombotic Microangiopathy

Introduction: Complement-mediated thrombotic microangiopathy (CM-TMA) is associated with microangiopathic hemolytic anemia (MAHA) and acute kidney injury. It requires a tissue biopsy for diagnosis. We present a case with aplastic anemia and transfusion related hemolysis (TRH) mistaken for CM-TMA treated with complement inhibitor (CI). Case Description: 78-year-old female with endometrial carcinoma and chronic kidney disease stage 3b presented with weakness, shortness of breath and loose stools after radiation therapy. She had completed carboplatin/paclitaxel/trastuzumab and received trastuzumab 3 weeks ago. Initial laboratory data included hemoglobin 6g/dL, platelets 61K, creatinine 2.5mg/dl, AST 220U/L, ALT 217U/L, total bilirubin 26mg/dL haptoglobin <10mg/dL, rare schistocytes on smear, normal ADAMTS13 and negative Coombs test. Infectious work up was negative and malignancy in remission. TMA from carboplatin was unlikely due to timing. Eculizumab was initiated for CM-TMA while awaiting complement testing. Due to ongoing anemia and thrombocytopenia, bone marrow biopsy was done showing hypoproliferative marrow and no malignancy. A steroid trial was pursued but did not improve the cytopenias. Patient was found to have anti-Jka antibodies likely causing TRH due to multiple transfusions. Renal biopsy showed acute tubular injury, subacute interstitial nephritis and myoglobin casts. Discussion: CIs have provided CM-TMA patients with lifesaving treatments by slowing endothelial dysfunction, hemolysis and organ failure. TMA can occur due to malignancy or antineoplastic agents. Early initiation of eculizumab has promising results, but can lead to hasty diagnosis, which can effect the immune system. This case reflects that laboratory values concerning for MAHA may not indicate TMA and other etiologies along with kidney biopsy must be considered.