Conjunctival Biopsy - Sarcoid

In General

Non-caseating granulomas can be detected in non-directed biopsies of the conjunctival fornix (i.e. a lesion is not seen on slit-lamp examination) in up to 50% of patients with systemic sarcoid.

For the Ophthalmologist

If no lesion is visible, the highest yield of non-caseating granulomas from a non-directed biopsy is from the conjunctival fornix (lymphoid tissue is concentrated in this area normally). An ellipse of tissue no less than 10 mm in length by 3 mm in width should be taken from the fornix and prepared to keep the tissue flat (see tissue preparation). The greater the area sampled, the higher the likelihood of detecting granulomatous inflammation. Both eyes may be biopsied in this fashion. The surgical morbidity is negligible.

For the Pathologist

The pathologist should prepare multiple cross-sections in a bread-loaf fashion. We generally recommend that the pathologist take N-1 sections where N = the length of the specimen in mm (for a 10 mm long specimen, we try to obtain 9 cross sections). All of the cross-sections are placed into one cassette with the technician instructed to embed the specimen "on edge". Multiple levels are cut through the block until the tissue is exhausted. At least three slides are prepared for each level, one stained with hematoxylin-eosin, and the other two kept in reserve for acid-fast and fungal stains if non-caseating granulomas are detected. With this technique, the pathologist need only examine 6-9 slides (one per level) for each case - a cost and time-effiecient method of tissue examination.

 

Non-caseating granuloma in a non-directed biopsy from the conjunctival fornix