Periarterial fibrosis in the spleen in idiopathic thrombocytopenic purpura.

The characteristic splenic lesion of idiopathic thrombocytopenic purpura (ITP) is said to be enlargement of the Malpighian bodies with the appearance of prominent germinal centers. Twenty-seven spleens therapeutically removed for ITP and 15 control spleens removed for trauma were reviewed. Lymphoid hyperplasia with germinal center formation was found more frequently in spleens with ITP than in the control spleens. In two of the spleens removed for ITP, a peculiar lesion was observed, which consisted of concentric layers of hyalinized material surrounding small arterioles, similar to the vascular "onionskinning" that commonly occurs in the spleens of patients with systemic lupus erythematosus. The clinical histories and laboratory data of these patients did not establish a diagnosis of systemic lupus erythematosus at the time of presentation.