Beryllium Lymphocyte Proliferation Test: Differential Diagnosis of Sarcoidosis and Chronic Beryllium Disease.

Abstract

Chronic beryllium disease (CBD) is considered a phenocopy of sarcoidosis, generally caused by occupational exposure to beryllium. Its diagnosis relies on the demonstration of beryllium sensitization by the beryllium lymphocyte proliferation test (BeLPT). How well does the BeLPT discriminate between CBD and sarcoidosis in patients with suspected beryllium exposure and what are the clinical characteristics of these 2 groups? BeLPT results and clinical characteristics of patients with suspected beryllium exposure were retrospectively analyzed. A total of 1,234 BeLPTs from 431 patients were included. Of 210 patients with established granulomatous disease, 87 patients (41.4%) were diagnosed with CBD and 106 (50.5%) were diagnosed with sarcoidosis; in 17 cases (8.1%), the BeLPT results were inconclusive. The remaining 221 patients had other diagnoses or could not be classified. A single BeLPT had a sensitivity of 61.5% (95% CI, 55.8-67.0) and a specificity of 90.8% (95% CI, 86.5-93.9). For split-sample tests, the sensitivity and specificity were 76.0% (95% CI, 67.7-82.8) and 80.4% (95% CI, 71.4-87.1), respectively. Patients with CBD had lower lung function than those with sarcoidosis, as measured by FVC (mean z score, -1.58 vs -0.75, respectively; P = .002). A restrictive pattern was more common in CBD than in sarcoidosis (41.0% vs 14.8%, respectively; OR, 3.99; P = .002). Despite low sensitivity, the BeLPT was able to detect CBD in 41.4% of patients with a granulomatous disease and suspected beryllium exposure. CBD was associated with lower lung function compared with sarcoidosis.