Pulmonary Pathologic Manifestations of Anti-Alanyl-tRNA Synthetase (Anti-PL-12)-Related Inflammatory Myopathy

- Patients with anti-aminoacyl-tRNA synthetase syndrome (ARS), a subset of idiopathic inflammatory myopathy, have a high prevalence of lung involvement. Autoantibodies directed against alanyl-tRNA synthetase (anti-PL-12 Abs) represent 1 of the 8 autoantibodies currently described under the rubric of ARS.

- To describe the clinical, radiographic, and pulmonary histopathologic findings in patients possessing anti-PL-12 autoantibodies.

- Patients with anti-PL-12 ARS were identified in the University of Pittsburgh Idiopathic Inflammatory Myopathy registry. Lung biopsies from 10 patients and lung explants from 2 patients with anti-PL-12 ARS were reviewed, together with chest computed tomography and clinical records.

- Patients primarily presented with dyspnea and variable combinations of cough, fever, mechanic's hands, Raynaud phenomenon, and skin and muscle involvement. Chest computed tomography most commonly showed lower lung zone-predominant reticular infiltrates and traction bronchiectasis, with or without honeycomb change. Surgical lung biopsies and pneumonectomies for lung transplantation revealed usual interstitial pneumonia in 8 of 12 cases (67%), nonspecific interstitial pneumonia in 2 of 12 cases (17%), and organizing pneumonia in 2 of 12 cases (17%). Lymphoplasmacytic interstitial inflammation with lymphoid aggregates was common.

- Lung disease is often the first manifestation of anti-PL-12 ARS. There are no pathognomonic histopathologic features to distinguish anti-PL-12 ARS-related lung disease from idiopathic variants of diffuse interstitial lung disease. Increased inflammation, lymphoid aggregates, and nonspecific interstitial pneumonia-like areas in a biopsy, as well as clinical features of mechanic's hands, Raynaud phenomenon, arthritis, and fever, should prompt pathologists to suggest involvement by ARS.