PURPOSE: ILD occurs in 5-30% of patients with PM/DM and may be the presenting feature in up to 30%. The presence of anti-tRNA synthetase antibodies is a risk factor for ILD. The presence of these antibodies in a patient presenting with ILD may have treatment and prognostic implications. We evaluated the prevalence of PL 12 antibodies in patients undergoing myositis specific antibody testing (MSA) and its clinical relevance.
METHODS: We retrospectively reviewed the medical records of all PL-12 positive patients.
RESULTS: 33/300 (11%) were positive on MSA testing. 7/33 (21%) of these were PL-12 positive. 5 were females. The median age was 52 yrs (39 to 64 yrs). Only 3 patients had evidence of myositis and/or skin rash. All patients presented to a pulmonologist with subacute onset of dyspnea on exertion and were diagnosed with ILD by surgical biopsy (4), transbronchial biopsy (2) and chest computed tomography (1). Pathologic diagnoses COP (3) NSIP (2) and UIP (1). The median FVC was 55 % predicted (48%-86%) and DLCO was 36% (18%-53%). Predominant finding on CT was fibrosis with minimal honeycombing. Serology was negative for any other myositis specific antibodies including Jo-1. Other autoantibodies included RF (4), SSA (3) and ANA (2). The diagnoses were DM (3), PM (1), UCTD (2) and overlap syndrome (RA/PM) (1). Patients were treated with steroids (7), azathioprine (3), cyclophosphamide (1) and IVIg (1). Lung function minimally improved/stabilized in all patients treated with immunosuppressive therapy.
CONCLUSION: ILD is a common presentation in patients who have a positive PL-12 antibody and includes COP, NSIP and UIP and appears to stabilize with immunosuppressive therapy.
CLINICAL IMPLICATIONS: The presence of PL 12 antibody in a patient with ILD should alert the physician to an underlying rheumatic diagnosis such as amyopathic DM. It also appears to be a harbinger of early ILD that requires aggressive treatment. The role of autoantibodies in pathogenesis of lung disease is unknown and needs further evaluation.
DISCLOSURE: Meena Kalluri, No Financial Disclosure Information; No Product/Research Disclosure Information