Late Onset of Congenital TTP: Case Presentation and Review of the Literature.

Background: Congential thrombotic thrombocytopenic purpura (cTTP) is a ultrarare genetic disorder caused by reduced or absent ADAMTS13 enzyme activity. In contrast to the acquired form of TTP, which results from inhibitory autoantibodies against ADAMTS13, cTTP arises due to mutations in the ADAMTS13 gene and lacks such inhibitors. cTTP commonly manifests during infancy through recurrent episodes of hemolytic anemia and signs of microvascular damage. Episodes are often precipitated by infections or physical stressors. Case presentation: A 23-year-old female patient presented to the emergency department with microangiopathic hemolytic anemia (MAHA), a reduced platelet count and acute kidney injury stage 3 (AKI 3). Three days before she had suffered a knee injury, which was treated with fentanyl. The peripheral-blood smear showed many schistocytes. A thrombotic microangiopathy was suspected and therapeutic plasma exchange (TPE) was initiated. ADAMTS13 activity on admission was 4% without a detectable inhibitory antibody and an inherited ADAMTS13 deficiency was suspected. Genetic testing revealed 2 presumably compound heterozygous variants in the ADAMTS13 gene, confirming the diagnosis of cTTP. After 3 TPE platelet count raised significantly with improvement of renal function. Thereafter the patient received prophylactic plasma infusions every 2 to 3 weeks. At 1-year follow-up she had a normal renal function and no recurrence of hemolytic anemia. Conclusion: The present case of cTTP is notable for its late onset at first presentation, with unusual severe renal impairment. Rapid diagnosis and timely initiation of treatment are critical. Differential diagnoses such as malignant hypertension, sepsis, and autoimmune diseases like systemic lupus erythematosus must be excluded.