PURPOSE:There is paucity of information regarding the histological findings of end-stage sarcoidosis.
METHODS:Explanted lungs and mediastinal lymph nodes from patients with sarcoidosis who underwent lung transplantation were examined by lung pathologists at our center. The pathologists were blinded to all clinical information except for the diagnosis of sarcoidosis and were asked to describe the histological patterns.
RESULTS:Total of seven subjects were enrolled in the study that consisted of 5 women and 2 men. Only 2 had the typical pattern of granulomatous lung disease with patchy areas of interstitial fibrosis expected of end-stage sarcoidosis. The remaining subjects had evidence of moderate to severe chronic interstitial pneumonitis not typically associated with sarcoidosis. Furthermore, 2 subjects had a pattern resembling usual interstitial pneumonitis (UIP) with fibroblastic foci. One had a single granuloma in the lung and mediastinal fibrosing granulomas; and the other was known to have granulomas in the mediastinal lymph nodes prior to transplant.
CONCLUSION:Advanced sarcoidosis is typically characterized by larger heterogeneous cystic spaces with residual granulomas in the lungs, and absence of significant chronic interstitial pneumonitis with no fibroblastic foci. Unexpectedly, we identified that majority of our cases showed moderate to severe chronic interstitial pneumonitis, not typically associated with sarcoidosis. Some of the cases even had a pattern indistinguishable from UIP with fibroblastic foci. The histological progression of granulomatous lung disease in sarcoidosis to end-stage fibrosis has not been fully investigated. Further studies are needed to elucidate the mechanism and clinical significance of the findings of UIP pattern in end-stage sarcoidosis.
CLINICAL IMPLICATIONS:The presence of UIP typically portend poor prognosis. It would be clinically relevant to further our understanding on the progression of typical sarcoid-related granulomatous lung disease into chronic interstitial pneumonitis in end-stage sarcoidosis.
DISCLOSURE:Hidenobu Shigemitsu, None.