Further evidence that exacerbation of ulcerative colitis causes the onset of immune thrombocytopenia: a clinical case.

Ulcerative colitis associated with immune-mediated thrombocytopenia is rare. It has been suggested that antigenic mimicry between platelet surface antigen and bacterial glycoprotein plays a role in this association. We present a case in which exacerbation of UC sequentially induced development of ITP associated with elevation of PAIgG. In the case, two episodes of ITP occurred, with each preceded by exacerbation of UC. After remission of UC, ITP remitted and PAIgG simultaneously decreased. In the first episode, the onset of ITP was about 1 month after the exacerbation of UC. However, in the second episode, the onset of ITP was much faster, 11 days after that of UC, and the magnitude of elevation of PAIgG was much higher in the second episode. This may provide further evidence that ITP is causally associated with UC, and is the result of immunostimulation from luminal antigens and altered immunoregulation.