Subpleural Fibroblastic Foci Identify a Unique Subset of Patients with Spontaneous Pneumothorax
Deborah A Belchis, Dale Johnson, Kris Shekitka. Johns Hopkins University School of Medicine, Baltimore, MD; Sinai Hospital of Baltimore, Baltimore, MD; St. Agnes Hospital, Baltimore, MD
Background: Spontaneous pneumothorax (SP) occurs in a heterogeneous group of patients with predisposing factors including inherited to acquired. Newly described entities, like Birt-Hoge-Dube, suggest there are underlying morphologic features which might alert the pathologist to the presence of an as yet unrecognized inherited or developmental disorder. The purpose of this study was to examine cases of SP to identify histopathologic patterns which may correlate with clinical entities.
Design: All cases of SP were selected from the pathology files over a 10 year period (2001-2011). The slides were examined for the presence of fibroblastic foci, eosinophilic pleuritis, pleural fibrosis/elastosis, airspace enlargement/emphysema, intraalveolar macrophages, cholesterol clefts, malignancy, intraparenchymal cysts and lymphangioleiomyomatosis. The significant morphologic features were confimed by another pathologist. The charts were abstracted for sex, age, family history, smoking and asthma history, and radiographic findings.
Results: 92 cases was retrieved. Slide review revealed 18 patients with fibroblastic foci. 6 had chronic lung disease and were excluded. The other 12 demonstrated a distinct lesion of patchy pleural fibrosis with a zonal pattern of dense, collagenized pleural fibrosis peripherally and loose fibroblastic areas at the leading edge. Interstitial fibrosis was absent. The adjacent alveoli ranged from unremarkable to showing mild type 2 hyperplasia. In some of the fibroblastic foci (FF), thick collagen bundles intermingled with the looser myxoid tissue. Ten patients were <25 (16-15) years old, one was 40 and one was 53. Both the 40 and 53 year old were non-smokers. Of the others, 6 were nonsmokers, 5 were smokers, one was unknown. Three had a history of asthma, 3 did not. The others were unknown. All involved the upper lobes. One additionally involved the lower lobe.
Conclusions: The discreet, patchy distribution of lesions and presence in only 13% of cases argue against a non-specific reactive process. These patients do not fulfill criteria for UIP: upper lobe involvement, no honeycomb change, predominantly young, no interstitial fibrosis. Some similarity to the newly described pleuroparenchymal fibroelastosis, an entity also associated with pneumothorax, is noted. Analysis of the elastic structure of the lung may be informative.
Wednesday, March 21, 2012 9:30 AM
Poster Session V # 303, Wednesday Morning