RESUMO
Thrombotic thrombocytopenic purpura (TTP) is a diffused microvascular occlusive disorder characterized by microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and ischemic organ dysfunction. In addition, this condition has been linked to an absence or dysfunction of ADAMTS13. Although TTP can occur due to various factors, such as bacteria, viruses, autoimmune disorders, drugs, connective tissue conditions, and solid tumors, it is a rare hematological complication associated with brucellosis. We describe the first case of a 9-year-old boy with acquired TTP with undetectable ADAMTS-13 assay secondary to Brucella infection. After initiating antimicrobial therapy, symptoms and laboratory abnormalities improved dramatically, with no recurrence of TTP in subsequent follow-ups.
RESUMO
INTRODUCTION: Von Willebrand factor (vWF) cleaving protease ADAMTS-13 has a key role for maintaining normal size of vWF. A deficiency or dysfunction of vWF cleaving protease is associated with ultra large vWF multimers and thrombotic microangiopathy. Patients with cancers have reduced levels of vWF cleaving protease. In this pilot study, we have evaluated whether or not deficiencies of ADAMTS-13 were present in myelodysplastic syndromes (MDS). Moreover, we assessed if a reduction in basal levels of ADAMTS-13 may play a role in the prognosis of MDS. PATIENTS AND METHODS: We measured and compared the levels of vWF cleaving protease ADAMTS-13 in 100 patients with MDS and 35 healthy controls. Patients were divided into 2 groups according to the International Prognostic Scoring System: group I consisting of 44 patients with low-risk MDS and group II of 56 patients with high-risk MDS. Patients with high-risk and low-risk MDS presented significantly lower levels of ADAMTS-13 than controls (P < .001 and P = .0177, respectively). High-risk patients had significantly lower levels of ADAMTS-13 when compared with the low-risk group (P < .001). RESULTS: We found that reduced levels of ADAMTS-13 have a relationship with overall survival (P < .001). Statistical analysis showed that ADAMTS-13 correlates with cytogenetics (P < .001) and a tendency of slight correlation with platelet count and basal levels of ADAMTS-13 (R, 0.35; P value, 0.001). Moreover, we found that levels of ADAMTS-13 have correlation with response to treatment (P < .001). CONCLUSIONS: ADAMTS-13 in MDS might represent a surrogate marker of prognosis, response to therapy, or disease progression. Further studies are needed.