[Clinical characteristics of hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP) in adult].

Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) were originally described as separate disease entities. Recently, HUS and TTP have been considered a single disease, because of the identical microangiopathic lesion. In the present study, we investigated the clinical and histological characteristics of HUS/TTP. Eleven patients with a definite diagnosis of HUS/TTP were found from a cohort of adult patients who were admitted to Kitasato University Hospital in the past two decades. Their clinical and histological characteristics were retrospectively analyzed. All of the 11 patients with HUS/TTP were sporadic and non-diarrheal cases with a mean age of 49 years +/- 10. Preceding episodes of flu-like syndrome and the administration of mitomycin C were observed in 3 and 5 patients, respectively. On admission, two of 10 patients with renal dysfunction required dialysis treatment, while none developed nephrotic syndrome. Six patients showed CNS manifestation, such as consciousness disturbance and convulsion. Three patients with severe hypertension did not show consciousness disturbance. As for the final outcome, 6 patients recovered and the remaining 5 died. Two died after 60 hospital days. In the histopathological investigation, renal biopsy specimen showed narrowing of the capillary loops in the glomeruli due to swelling of the endothelial cells, double contour of the glomerular basement membrane, or mesangial cell necrosis and sclerosis. In the autopsy specimen, internal organ infarction with fibrin thrombi in small arteries was observed in multiple organs, such as brain, kidneys, hearts, lungs, jejunum, liver, pancreas, adrenal glands and pituitary gland. A circumferential myocardial infarction with hyaline thrombi in the medial layer of myocardium was characteristic of HUS/TTP. In conclusion, microangiopathic lesions with infarction spread widely throughout various organs in HUS/TTP. Involvement of internal organs, not to mention kidneys and brain, is lethal and their prognosis remains poor.