To characterize the clinical features of patients with direct immunofluorescence (DIF)-negative mucous membrane pemphigoid (MMP).

Retrospective case series.

Thirty-six patients who underwent a conjunctival biopsy for suspected MMP were included. Demographic and clinical information was collected. Main outcome measures included visual acuity, Foster stages, presence of extraocular involvement, history of autoimmune disease, and durations of follow-up.

Thirty-two patients had a negative DIF. Of those, 2 had a positive DIF on repeat biopsy. Eleven showed progression of conjunctival scarring during a median follow-up of 42 months (range, 8-100 months) and were diagnosed with biopsy-negative MMP. Another 11 patients with a median follow-up of 54 months (range, 15-138 months) were diagnosed with cicatrizing conjunctivitis of other causes. The median visual acuity of patients with biopsy-negative MMP at presentation was significantly lower compared to patients with cicatrizing conjunctivitis of other causes (20/400 vs 20/40, P = .02). Conjunctival scarring score at presentation in both biopsy-positive and biopsy-negative MMP groups was significantly higher compared to patients with cicatrizing conjunctivitis of other causes (median Foster stage, 3 vs 1, P = .009; and 3 vs 1, P = .01, respectively).

Patients with progressive cicatrizing conjunctivitis likely have MMP in the absence of alternate diagnoses. Our findings emphasize that suspicion for MMP must remain high for patients who have Foster stage 3 conjunctival scarring on presentation or worsening of scarring during follow-up, even in the setting of negative DIF.