Intraalveolar Fibrin Is Associated with Poor Outcomes in Cryptogenic Organizing Pneumonia
Michiya Nishino, Susan K Mathai, Walter J O'Donnell, Richard L Kradin. Massachusetts General Hospital, Boston, MA
Background: Organizing pneumonia (OP) is a histopathologic pattern of response to lung injury that is characterized by intraalveolar filling by fibroblasts aggregated with immature collagen. Fibrin is a marker of acute microvascular injury, and variable amounts of intraalveolar fibrin are seen in OP; however, its relevance to clinical outcomes has not been assessed. We hypothesize that intraalveolar fibrin deposition in lung tissue of patients with idiopathic OP is associated with poor clinical outcomes.
Design: Patients with OP on pathology were identified, and hematoxylin and eosin-stained sections of formalin-fixed lung tissue were subclassified by the amount of intraalveolar fibrin associated with OP (none/low vs. medium/high). Biopsies with hyaline membranes and cases for which clinical data was not available were excluded. Clinical features (survival, rehospitalization, clinical relapse, pulmonary function testing, treatment, chest imaging) were compared between the groups at twelve months after biopsy. A poor clinical outcome was defined as a clinical relapse, hospitalization, or death due to OP.
Results: Eighty-six patients had histopathologic OP on biopsy; 32 patients were exluded due to lack of clinical follow-up, presence of another predominant histopathologic pattern, and presence of hyaline membranes. Of the remaining 54 patients with OP, 26 patients were further excluded due to presence of underlying systemic disease (e.g., autoimmune disease, malignancy) or drug-related pulmonary toxicity, leaving 28 patients with cryptogenic OP. Average age at biopsy was 62, and 11 patients showed significant intraalveolar fibrin (medium/high). Patients with intraalveolar fibrin were more likely to relapse (55% vs. 13%, p=0.03). This difference in groups persisted when patients with suspected aspiration (n=6) were excluded (p=0.02).
Conclusions: The histopathological presence of significant intraalveolar fibrin in lung biopsies of patients with cryptogenic organizing pneumonia appears to augur a less favorable clinical outcome.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 297, Tuesday Afternoon