Caplan's syndrome of rheumatoid arthritis with pneumoconiosis is characterized by

Ans. a (Lung nodules and diffuse pulmonary fibrosis). (Ref. Harrison, Medicine, 16th ed., 1524)CAPLAN'S SYNDROME# Caplan's syndrome is characterized by triad of- Pulmonary nodules,- Pneumoconiosis (progressive massive fibrosis), and/in- Rheumatoid disease (seropositive).# The immuno-pathological mechanism involves:- Direct cytotoxicity of inorganic dust- Stimulation of reactive oxygen- Activation of macrophages to produce cytokines and TNF alpha (fibrogenic factor)- Increased protease activity- Increased activation of alpha 1 antitrypsin and leucocyte elastase activity.