Gingival biopsy in thrombotic thrombocytopenic purpura.

Gingival biopsy has been advocated as a readily available, safe, rapid histologic confirmation of the clinical diagnosis of thrombotic thrombocytopenic purpura. Eighteen gingival biopsies from 16 patients with proven thrombotic thrombocytopenic purpura were reviewed. Seven (39%) showed characteristic histologic changes: [1] subendothelial hyalinelike deposits; [2] intraluminal deposits; [3] lack of inflammatory change in vessels and stroma. To assess specificity, gingival sections from 154 patients with oral pathology only and from 50 unselected autopsies were reviewed: 10% to 20% of biopsies from patients with oral pathology only (primarily inflammation) and three of 50 autopsy specimens showed occasional intraluminal deposits but no subendothelial deposits. In addition, other histologic features permitted them to be distinguished from thrombotic thrombocytopenic purpura. We conclude that gingival biopsy in thrombotic thrombocytopenic purpura, although helful in confirming the diagnosis, is less often positive than has been suggested. Biopsy of grossly inflamed gingiva should be avoided.