Delayed Processing of Conjunctival Biopsies for Direct Immunofluorescence in Mucous Membrane Pemphigoid in Resource Limited Settings

PURPOSE: To evaluate the feasibility and assess outcomes of using optimal cutting temperature (OCT) compound as a transport medium without immediate freezing, for the delayed processing of conjunctival biopsies in patients with suspected ocular mucous membrane pemphigoid. METHODS: This retrospective study was conducted over 2 years and included suspected ocular mucous membrane pemphigoid patients who underwent conjunctival biopsy. The samples were transported in OCT compound in cold chain without immediate freezing and processed in a laboratory situated nearly 300 km away. The time from biopsy to processing, biopsy results including basement membrane (BM) presence, and direct immunofluorescence (DIF) outcomes were analyzed. RESULTS: A total of 71 patients (139 eyes) were included in the study with a slight female preponderance. The samples were processed after a median of 4 days (interquartile range: 3-5) after the date of collection. An intact BM was present in 137/139 samples (99%). Of the 71 patients, 43 (61%) showed presence of immunoreactants in the BM on DIF. C3 and IgA were the most frequently identified markers. CONCLUSIONS: OCT compound can be used as a transport medium for conjunctival biopsy samples processed for DIF. Delayed processing does not affect tissue viability or the diagnostic outcomes. Hence, it is a useful method for low resource settings where a specialized laboratory for DIF testing is not available.