Toxic exposure, allergy/atopy, and autoimmune disease are a few of the many etiologies of noninfectious conjunctivitis. Often, the inflammation found in these conditions is histologically nonspecific, although the presence of eosinophils in the tissue suggests an allergic/atopic etiology.
Mucous membrane pemphigoid (MMP; also known as ocular cicatricial pemphigoid) is a form of cicatrizing conjunctivitis of autoimmune etiology. Typically, it involves not only the conjunctiva (Fig 5-4A) but also other mucous membranes; in approximately 25% of affected patients, MMP involves the skin. When this diagnosis is suspected clinically, conjunctival biopsy is performed to establish the diagnosis. Half of the specimen is submitted in formalin for routine histologic examination, and half is submitted in a special medium (eg, Michel or Zeus) or saline for direct immunofluorescence analysis. Histologic findings are generally nonspecific but typically show a subepithelial, bandlike, mixed inflammatory cell infiltrate rich in plasma cells. The overlying epithelium may demonstrate squamous metaplasia with keratinization and loss of goblet cells. Bullae are occasionally present (Fig 5-4B). Immunofluorescence is the gold standard for diagnosis of MMP and demonstrates linear deposition of immunoglobulins (IgG, IgM, and/or IgA) and/or complement (C3) along the epithelial basement membrane (Fig 5-4C). The clinician must bear in mind that the sensitivity of immunofluorescence may be as low as 50% (particularly in long-standing cases with severe cicatrization). Thus, a negative result does not rule out MMP.
Figure 5-4 Mucous membrane pemphigoid (MMP). A, Clinical photograph. Note the conjunctival injection, symblepharon formation, shortening of the inferior fornix, and conjunctival/eyelid cicatrization. B, Histology shows epithelial bullae (arrows) and a dense chronic inflammatory cell infiltrate in the stroma (arrowheads).C, Direct immunofluorescent staining of unfixed tissue demonstrates immunoglobulin deposition along the epithelial basement membrane (arrowheads) in MMP.
(Part A courtesy of Andrew J.W. Huang, MD; part B courtesy of George J. Harocopos, MD.)
Labowsky MT, Stinnett SS, Liss J, Daluvoy M, Hall RP, Sheih C. Clinical implications of direct immunofluorescence findings in patients with ocular mucous membrane pemphigoid. Am J Ophthalmol. 2017;183:48–55.
Queisi MM, Zein M, Lamba N, Mees H, Foster CS. Update on ocular cicatricial pemphigoid and emerging treatments. Surv Ophthalmol. 2016;61(3):314–317.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.