ANCA-Negative Pulmonary-Renal Syndrome with Pathologic Findings Suggesting Thrombotic Thrombocytopenic Purpura

Background: thrombotic thrombocytopenic purpura (ttp) is a rare disease characterized bymicroangiopathic hemolytic anemia, thrombocytopenia, neurologic abnormalities, fever and renaldysfunction. the disease classically spares the lung tissue, but recently some cases were reportedthat presented with respiratory involvement (adult respiratory distress syndrome or pulmonaryrenalsyndrome). presentation with pulmonary-renal syndrome has rarely been reported.case presentation: we report a 14-yaers-old boy admitted to the hospital because of abiochemical evidence of renal failure. two days after admission he developed a high fever,hemoptysis and respiratory distress. open kidney biopsy was performed and confirmed thediagnosis and finally the patient expired due to neurologic involvement.conclusion: this case is presented to discuss the need to update the criteria for ttp diagnosis andconsidering ttp in the differential diagnosis of pulmonary renal syndromes.