Granulomas in UIP

Cholesterol granulomas

Occasionally, ill-defined granulomas may be found in biopsies or lungs resected prior to transplant.The granulomas shown below begin in air spaces, but may become incorporated into the interstitium as is occurring with the granuloma on the left. Epithelioid cells and multinucleated giant cells are present around prominent, empty clefts (cholesterol clefts), from which crystalline material was dissolved during processing. The clefts are thought to represent cholesterol liberated from cell debris. Cholesterol granulomas occur in other conditions, including plexogenic angiopathy.

Ill-defined, non-necrotizing granulomas

This type of granuloma was found in another patient undergoing lung transplant for UIP. The giant cells have peripheral nuclei (Langhans' type) and are mixed with lymphoid cells.

In this case, an infectious etiology is possible although no organisms were seen on stains for mycobacteria or fungi. Hypersensitivity pneumonia is also a possible cause. A history of organic dust exposure should be carefully sought by history and serologic tests so that the patient can be removed from the antigen, if identified. Although no foreign material was noted even with polarized light, these granulomas might be a response to aspirated material. In this regard, 16 of 17 patients with UIP were shown to have prolonged periods of esophageal acid exposure, and while aspiration is not believed to be the cause of the UIP, it may contribute to inflammation [1].


1. Tobin R, Pope II C, Pellegrini C, Emond M, Sillery J, Raghu G. Increased prevalence of gastroesophageal reflux in patients with idiopathic pulmonary fibrosis. 1998; 158:1804-1808.

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