Pieces of the Puzzle: Using Nonspecific Interstitial Pneumonia (NSIP) as a Clue to the Diagnosis of Connective Tissue Disease in Usual Interstitial Pneumonia (UIP)
NA Cipriani, S Bhorade, E Garrity, W Vigneswaran, T Krausz, AN Husain. University of Chicago, Chicago
Background: UIP is the most common form of chronic interstitial lung disease, comprising up to 70% of cases. It can occur idiopathically (I-UIP) or in the setting of connective tissue disease (CTD-UIP). Patients with CTD have a better prognosis than those without, although both populations often undergo lung transplantation. Prior studies have demonstrated a preponderance of the NSIP pattern in CTD patients, or even coexisting NSIP and UIP. We aim to evaluate the utility of finding coexisting multi-lobar NSIP and UIP as a tool to aid in the differentiation between I-UIP and CTD-UIP.
Design: With IRB approval, explanted lung tissue from 8 patients (4 I-UIP, 4 CTD-UIP) was identified using an existing database: 2 I-UIP patients with bilateral explants, 1 with right and 1 with left-sided explants; 4 CTD-UIP patients with bilateral explants. Slides from all lobes were evaluated for the presence of NSIP in areas away from fibrosis/honeycombing.
Results: 1 of 4 I-UIP patients had cellular NSIP in all lobes and 1 had patchy fibrotic NSIP. 3 of 4 CTD-UIP patients had cellular NSIP in all lobes. In both groups, patients without multi-lobar NSIP demonstrated widened alveolar walls only in the areas adjacent to fibrosis, which was not seen in areas distant from fibrosis.
Conclusions: Although the presence of coexisting multi-lobar cellular NSIP is not exclusive to CTD-UIP patients, it does occur with a higher prevalence (25% in I-UIP versus 75% in CTD-UIP), and therefore may serve as a clue to the presence of CTD. Common to both groups are widened alveolar walls near areas of fibrosis, which may mimic fibrotic NSIP. Hence, alveoli near fibrotic/honeycombed areas cannot be used to evaluate for NSIP, and pathologists must be strict in examining pulmonary parenchyma at some distance from typical UIP fibrosis.
Monday, March 9, 2009 1:00 PM
Poster Session II # 228, Monday Afternoon