Conjunctival biopsy to diagnose neurosarcoidosis in patients with inflammatory nervous system disease of unknown etiology.

Neurosarcoidosis mimics many neurologic diseases and poses a major diagnostic challenge. Blind conjunctival biopsy is often used to help diagnose neurosarcoidosis when biopsy of affected nervous system tissue is not feasible. While this test is relatively inexpensive and well-tolerated, the diagnostic yield in patients with inflammatory nervous system disease of unknown etiology remained uncertain. We evaluated 440 patients who underwent conjunctival biopsy due to concern for neurosarcoidosis. Only a small minority of patients (3%) had positive conjunctival biopsies consistent with sarcoidosis, and some patients (1%) with positive biopsies were found to have a cause for their neurologic disease other than neurosarcoidosis. Many patients (14%) had negative conjunctival biopsies but were later confirmed to have neurosarcoidosis after additional evaluations. This study demonstrates that conjunctival biopsy has a low diagnostic yield for neurosarcoidosis in patients with inflammatory nervous system disease and suggests that alternative diagnostic means should be pursued.