- Berylliosis is a respiratory disease caused by a chronic, high-level inhalation of Beryllium dust and may occur in workers of nuclear and high-technology industries. The pathogenesis of berylliosis is distinct from that of other pneumoconioses and is not driven by the alveolar macrophage. Instead, it appears that in certain genetically-susceptible individuals, the presence of berrylium can activate CD4+ T-cells to coordinate a delayed-type hypersensitivity reaction toward self-antigens. Morphologically, berylliosis manifests as progressive pulmonary fibrosis with the presence of non-caseating granulomas, highlighting the role of delayed-type hypersensitivity in the pathogenesis of the disease. Clinically, patients display insidious but progressive onset of symptoms associated with declining respiratory function.