Pathology Presents: Diagnosing Diffuse Fibrotic Lung Disease in 2015
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Brandon T. Larsen, MD, PhD
Department of Pathology
University of Arizona College of Medicine
- Faculty Sponsor
Chuck Murry, MD, PhD
Diagnosing Diffuse Fibrotic Lung Disease in 2015: Clues to Distinguish “Idiopathic Pulmonary Fibrosis” from Potential Mimics
For most surgical pathologists, wedge biopsies from patients with diffuse fibrotic lung disease are challenging and anxiety-provoking, given the uncommon occurrence of these diseases. This anxiety is exacerbated by confusing terminology and new and rapidly evolving international consensus criteria for diagnosis. In late 2014, the advent of two novel FDA-approved medications for idiopathic pulmonary fibrosis (IPF) made accurate histopathologic classification even more essential, not only for establishing prognosis, but also for appropriate selection of treatment. IPF is the most common form of progressive diffuse lung scarring in older adults, and is manifest histopathologically as the “usual interstitial pneumonia” (UIP) pattern. IPF is not the only disease that causes a UIP pattern of fibrosis, however, and several other entities may present with patterns of patchy fibrosis that mimic the idiopathic UIP pattern. In the last year, it has become incumbent on pathologists to diagnose not only the pattern of fibrosis that they see, but also to distinguish between the various entities that can produce a UIP or UIP-like pattern of fibrosis, and provide their clinicians with the most likely etiology whenever possible. Often, clues in the lung biopsy may offer the first suggestion of a fibrotic lung disease other than IPF, and accurate classification is important for prognosis, treatment, and the development of future therapies. In his seminar, Dr. Larsen will first review the current consensus criteria for diagnosing IPF, and then will address the practical dilemma that arises when a surgical lung biopsy has clear evidence of patchy (spatially heterogeneous) fibrosis, but the clinical, imaging, and/or histopathologic sub-characteristics suggest something other than IPF. Six fibrotic lung diseases (connective tissue disease-associated interstitial lung disease, chronic hypersensitivity pneumonitis, advanced pulmonary Langerhans cell histiocytosis, end-stage pulmonary sarcoidosis, Erdheim-Chester disease, and Hermansky-Pudlak syndrome) will be presented, each with detailed clinical, radiologic, and histopathologic attributes, emphasizing similarities to and differences from IPF.