International Kveim histology trial.
An histological analysis of Kveim-test biopsies performed on a total of 306 patients including those with sarcoidosis, Crohn's disease, tuberculosis, and collagen disease is presented. Five main Kveim suspensions, "antigens," were used in the survey, Colindale K 12, Lot 5, Marburg 2 and 3, Commonwealth Serum Laboratory (CSL) early batches, 001/2/3 and late batches, 005/6. The biopsies were read blind by two observers (overall agreement 75%), the nature of the antigen and disease later disclosed, and the finding statistically analysed. It was agreed that focal epithelioid-cell collections remain as the essential criteria for the diagnosis of Kveim positivity. Diffuse epithelioid cells, Langhans' giant cells, lymphocytes, and necrosis are associated with focal epithelioid cells and hence Kveim positivity. Steroids were found to inhibit Kveim positivity. Observer disagreements were mainly due to difficulties in distinguishing macrophages from true epithelioid cells. We conclude that doubtful cells should be ignored in deciding Kveim positivity. Lymph-node-derived Kveim antigens were the most sarcoid-specific. They were more granulogenic and produced more necrosis, despite also producing the most foreign material. It is recommended that validation of new Kveim antigens must include adequate testing on patients with Crohn's disease, as the more nonspecific antigens were shown to give equal positive rates in sarcoidosis and Crohn's disease.