Racial differences in sarcoidosis granuloma density.

STUDY
OBJECTIVES: While sarcoidosis generally inflicts a greater morbidity on African-American compared with Caucasian patients, no studies have examined whether racial differences exist in the intensity of the histologic hallmark of sarcoidosis, noncaseating granulomas. DESIGN AND
SETTING: The study was conducted as a retrospective case series in a tertiary referral center. PATIENTS: The study included 187 patients with histopathologic confirmation of sarcoidosis by trans- and/or endobronchial biopsy between July 1991 and December 2001. MEASUREMENTS AND
RESULTS: Granuloma density was the average number of granulomas per biopsy piece on the slide with the most intense granulomatous inflammation at fourfold magnification. Overall, African-American patients had a twofold greater median granuloma density than Caucasians (p = 0.005). In a negative binomial multivariate model, radiographic pattern had the strongest association with granuloma density, with Scadding stage II and III patients having adjusted granuloma densities of 60% (p = 0.005) and 105% (p = 0.0001) higher than stage I patients. In the specific-tissue types, radiographic stage-adjusted granuloma densities in African-American patients were 49% greater in bronchial tissue (p = 0.03), but only a 27% greater in alveolar tissue (p = 0.51).
CONCLUSIONS: A greater granuloma density in bronchiolar lung tissue of African-American sarcoidosis patients may explain racial differences in diagnostic yield by lung biopsy and disease severity at diagnosis. This association persists even after controlling for Scadding radiographic stage, a measure of disease severity strongly associated with granuloma density.