[HSC transplantation-associated intestinal thrombotic microangiopathy: clinical pathological features, diagnosis criteria and treatment].

Thrombotic microangiopathy (TMA) is a lethal transplantation-associated complication which exactly likes acute intestinal graft-versus-host disease (GVHD) in the clinical manifestation. 373 consecutive patients with hematological diseases received family HLA matched or mismatched HCT from May, 2002 to July, 2004. To analyse the clinical and pathological characteristics of TMA, 30 patients who suffered from severe diarrhea and received colonoscopic examination and gut biopsy were retrospectively analyzed. The results indicated that 7 patients originally diagnosed as gut GVHD showed the pathological evidence of enteric TMA. The incidence of TMA was 7 out of 30 specimen (23.3%). Pathological evidence of enteric TMA shown microvascular disorder characterized by thrombus in the capillary without infiltration of lymphocytes and perivascular hemorrhages in the mucosa, swelling and focal denudation of epithelial cells. All patients with TMA were associated with cytomegalovirus (CMV) antigenemia/disease. Among these patients, 4 cases, who only showed TMA without the evidence of gut GVHD pathologically, displayed treatment-resistant bloody diarrhea, renal failure, veno-occlusive disease, hemorrhagic cystitis, hemolytic anemia as well as thrombocytopenia. But the other 3 cases, with co-existence of both TMA and GVHD pathological characteristics had better treatment response. Survival analysis indicated that 3 patients with TMA-GVHD survived for 461 to 536 days but three out of four TMA patients died from VOD with liver failure as well as multiple organ failure during 101 to 254 days after HCT. In conclusion, to better diagnose those patients with severe and refractory diarrhea following HCT, pathological examination may indicate crux evidence to identify intestinal TMA from gut GVHD. Furthermore, this primary report has first evidenced that TMA and TMA-GVHD are two pathologically well-recognized subtypes with the difference between the pathological characteristics, treatment response and clinical outcomes.