Laboratory Studies
Diagnosis of ocular cicatricial pemphigoid (OCP) is based on clinical presentation and immunohistochemical studies of the conjunctiva, which can reveal pathognomonic features of the disease. [5]
No specific laboratory assays are available to diagnose or monitor the activity of OCP; however, such assays are being developed. In one study, decreased serum levels of interleukin 6 and increased serum levels of tumor necrosis factor alpha were described in patients with active OCP, but the use of these tests is not common in clinical practice. [6]
Individuals receiving immunosuppressive agents require appropriate laboratory studies to monitor the therapy.
Procedures
Conjunctival biopsy
A definitive diagnosis of ocular cicatricial pemphigoid (OCP) is made by demonstration of linear deposition of immunoreactants (eg, IgG, IgA, complement component C3 or C4) at the BMZ of the biopsy specimen of inflamed conjunctiva using immunofluorescent or immunoperoxidase technique.
Other histologic techniques, such as hematoxylin and eosin staining, periodic-acid Schiff (PAS), and Giemsa staining, are not diagnostically specific.
Only experienced laboratory technicians should process conjunctival tissue to obtain the highest possible diagnostic yield and sensitivity. A negative or inconclusive biopsy result may be secondary to poor biopsy technique or poor handling of the specimen. [7] Indeed, two recent reports led the authors to abandon biopsy-proof efforts and to simply treat patients whom they believed had OCP. [8, 9] The authors of this article believe that this is ill-advised and recommend extra efforts at amplification strategies for definitive diagnosis. [10]
Histologic Findings
Hematoxylin and eosin staining shows the conjunctiva infiltrated with neutrophils, macrophages, and Langerhans cells. PAS goblet cells are decreased or absent in patients with advanced ocular cicatricial pemphigoid (OCP). Patients with active OCP have excess mucus production and strands of mucus-like material in the inferior fornix.
Observations with scanning and transmission electron microscopy indicate mucus present on the surface of the conjunctiva, even though goblet cells are not seen. Giemsa stain results show that the total mast cell number and ratio of connective tissue mast cells to mucosal mast cells are significantly higher than in normal conjunctiva.
The deposition of IgG, IgA, C4, or C3 is highlighted by fluorescein or rhodamine-labeled antibodies, which are directed against immunoglobulins and complement components. The diagnostic sensitivity of immunofluorescence alone is approximately 50-52%.
Immunoperoxidase technique is required when immunofluorescence study findings are negative, yet the clinical presentation strongly suggests OCP. The immunoperoxidase technique is approximately 1,000 times more sensitive than immunofluorescence. Immunoperoxidase can detect the deposition of immunoreactants at the BMZ in smaller amounts. The diagnostic sensitivity of immunoperoxidase is 83%, an increase of 31% compared to immunofluorescence technique.
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Ocular cicatricial pemphigoid, stage II. Note the fornix foreshortening.
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Ocular cicatricial pemphigoid, stage III. Note the symblepharon.
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Ocular cicatricial pemphigoid, stage IV. Note the ankyloblepharon and ocular surface keratinization.
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Corneal neovascularization with ulceration and stromal thinning after persistent epithelial defect in a patient with ocular cicatricial pemphigoid.
