Hypersensitivity Pneumonia: Where Do Granulomas and Giant Cells Live?
Mathieu C Castonguay, Jay H Ryu, Eunhee S Yi, Henry D Tazelaar. Dalhousie University, Halifax, NS, Canada; Mayo Clinic, Rochester, MN; Mayo Clinic, Scottsdale, AZ
Background: Characteristic histologic findings in hypersensitivity pneumonia (HP) include chronic bronchiolitis, interstitial pneumonia, non-necrotizing granulomas, and isolated multinucleated giant cells (MNGCs). Although the location of granulomas and MNGCs is said to be of importance in the differential diagnosis (“they should be interstitial in HP”), their distribution has not yet been systematically evaluated. This study was undertaken to determine whether they could also be found in airspaces.
Design: Retrospective study spanning 16 years (1997–2012), evaluating 40 patients with a clinicopathologic diagnosis of HP who underwent lung wedge biopsy at our institution; 2 patients also underwent lung transplantation. The medical records were reviewed for demographic, clinical, and imaging features. Glass slides prepared from wedge biopsy and explant specimens were reviewed by three pathologists to assess multiple histologic features of HP, including the location of granulomas and isolated MNGCs.
Results: Patient ages were from 16 to 79 years (mean, 59), with 24 (60%) women. Historical exposures to potentially responsible antigens were identified in 27 patients, 8 of whom had confirmatory serologies. Classic features of HP were present in the majority of patients (see Table). Granulomas were seen in the airspaces of 28 patients (and strictly so in 6); similarly, isolated MNGCs were present in the airspaces of 25 patients (and solely so in 7); both granulomas and MNGCs were confined to airspaces in 3 patients (each with antigen exposure). Pleural granulomas were seen in 3 cases, and pleural MNGCs in 1 additional case (3 with antigen exposure).
|Histologic Feature||Present (%)||Absent (%)|
|Interstitial Pneumonia||Centrilobular Accentuation||75||25|
|Peripheral with Honeycombing||15||85|