Role of Electron Microscopy in the Diagnosis of Ocular Mucous Membrane Pemphigoid

Purpose: To evaluate the role of electron microscopy (EM) for the diagnosis of ocular mucous membrane pemphigoid (MMP) among patients with cicatrizing conjunctivitis. Design: Retrospective case series. Participants: One hundred twenty-eight patients with cicatrizing conjunctivitis referred for the evaluation of possible ocular MMP between January 1985 and February 2002 who underwent conjunctival biopsy and evaluation with EM and direct immunofluorescent (DIF) techniques. Methods: The diagnosis of each patient was based on DIF techniques. The reproducibility of EM readings was measured by assessing intraobserver and interobserver variability. The diagnosis from EM was compared to the DIF diagnosis from the same patient to evaluate the validity of the EM diagnosis. Main Outcome Measures: Sensitivity, specificity, positive predictive value, and negative predictive value of EM for diagnosing ocular MMP. Results: One hundred twenty-six of 128 conjunctival biopsies were available for evaluation of EM findings. The percent agreement between 2 readings from the same observer was 92%, and the percent agreement between 2 independent observers was 78%. The sensitivity and specificity of EM for the diagnosis of ocular MMP were 51% and 72%, respectively. The positive predictive value of EM for the diagnosis of ocular MMP was 49%. Conclusions: The reproducibility of EM findings was good as indicated by high percent agreement for both intraobserver and interobserver measurements. However, the sensitivity, specificity, and positive predictive value of EM for the diagnosis of ocular MMP was low. It seems that EM has limited usefulness in the diagnosis of ocular MMP.