Non-sarcoid granulomatous disease with involvement of the lungs

Pulmonary granulomatous disease can severely damage the lungs and represents a rather uniform response of the lungs to a multitude of different stimuli. Histologically, granulomatas can be broadly classified as either hypersensitivity-type or foreign-body-type. A wide variety of infectious and non-infectious etiologies discussed in this review have been identified as causes of granulomatous inflammation of the lungs. An infectious origin should always be excluded since specific etiologic therapy may be implemented. Culture techniques for microorganisms or fungi and standard or special stains of tissue samples are crucial to establish the specific etiologies. The mechanisms leading to granuloma formation are still poorly understood, but the role of parenchymal cells, fibroblasts, endothelial and epithelial cells, and cytokines, has been better appreciated; all of them are important in the initiation, maintenance, and resolution of the lesion. Whether these new insights will finally lead to new ways of treating lung granuloma remains to be determined.