BONE-MARROW TRANSPLANT-ASSOCIATED THROMBOTIC MICROANGIOPATHY - A CASESERIES

Bone marrow transplant-associated thrombotic microangiopathy (BMT-TM) has been reported with widely varying frequencies and outcomes. Theref ore a BMT-TM grading system (0-4) was developed based on the lactate d ehydrogenase (LD) level and percentage (%) fragmented cells (FC) as fo llows: grade 0, normal or up arrow LD and FC less than or equal to 1.2 %; grade 1, normal LD and FC greater than or equal to 1.3%; grade 2, u p arrow LD and FC = 1.3-4.8%; grade 3 up arrow LD and FC = 4.9-9.6%; a nd grade 4, up arrow LD and FC greater than or equal to 9.7%. Patients with grade 0 and grade 1 BMT-TM did not differ in clinical parameters . Twenty two patients had BMT-TM grade 24. These were observed for out come. Seven of 10 with grade 2 BMT-TM had resolution of BMT-TM a media n of 99 days (range 50-229 days) from diagnosis. This occurred spontan eously in five and following discontinuance of cyclosporine (CsA) in t wo. The remaining three had persistent BMT-TM at grade 2 (two patients ) and grade 1 (one patient). In contrast, none with grade 3-4 BMT-TM h ad resolution, Seven with grades 3-4 BMT-TM underwent a variety of pla sma exchange procedures; six had partial hematologic responses, Patien ts with grades 3-4 BMT-TM had a poorer survival (median survival = 60 days) than those with grade 2 BMT-TM where the median survival has not been reached (P = 0.018). These results indicate that BMT-TM is commo n following allogeneic-BMT and the outcome is dependent on the grade. Those with grade 1-2 BMT-TM generally do well. In contrast, those with grades 3-4 BMT-TM have partial hematologic responses and poor outcome s.