Histopathologic findings in lung biopsies from patients with primary biliary cholangitis

Primary biliary cholangitis (PBC) is a progressive autoimmune disease of the liver causing destruction of intrahepatic bile ducts, associated with lymphocytic and granulomatous inflammation. PBC has been associated with many extrahepatic manifestations including interstitial lung disease. However, comprehensive pulmonary histopathology in PBC has not been well documented. Sixteen PBC patients who underwent lung biopsies were identified from surgical pathology files in three institutions. Histopathologic review was performed. Patient age ranged 41 to 79 years (median 55 years) and 15 patients (94%) were women. Specimens consisted of lobectomy (n = 1), surgical biopsies (n = 12), transthoracic needle biopsy (n = 1) and transbronchial biopsy (n = 2). Fifteen of 16 (94%) cases showed lymphocytic inflammation, mainly localized to peribronchiolar stroma and alveolar septa. Thirteen (81%) cases revealed non-necrotizing granulomas, most of which were poorly formed, reminiscent of those seen in liver biopsies from PBC patients. Six cases also showed eosinophilic infiltrates. Organizing pneumonia was seen in 7 cases. Four cases showed diffuse interstitial fibrosis with nonspecific interstitial pneumonia and usual interstitial pneumonia patterns. One patient underwent lobectomy for a mass lesion and was diagnosed with light chain deposition disease with underlying κ-restricted extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. In summary, PBC-associated histopathologic changes in the lung include lymphocytic inflammation predominantly around small airways and non-necrotizing granulomas in multiple compartments of lung tissue, which parallel PBC-associated histopathology in liver biopsies, often associated with other common patterns of diffuse lung disease.