More than meets the eye: IgG4-related disease presenting as isolated interstitial lung disease

Skin disorders and interstitial lung disease: Part I-Screening, diagnosis, and therapeutic principles

Numerous inflammatory, neoplastic, and genetic skin disorders are associated with interstitial lung disease (ILD), the fibrosing inflammation of lung parenchyma that has significant morbidity and mortality. Therefore, the dermatologist plays a major role in the early detection and appropriate referral of patients at risk for ILD. Part 1 of this 2-part CME outlines the pathophysiology of ILD and focuses on clinical screening and therapeutic principles applicable to dermatological patients who are at risk for ILD. Patients with clinical symptoms of ILD should be screened with pulmonary function tests and high-resolution chest computed tomography. Screening for pulmonary hypertension should be considered in high-risk patients. Early identification and elimination of pulmonary risk factors, including smoking and gastroesophageal reflux disease, are essential in improving respiratory outcomes. First-line treatment interventions for ILD in a dermatological setting include mycophenolate mofetil, but the choice of therapeutic agents depends on the nature of the primary disease, the severity of ILD, and comorbidities and should be the result of a multidisciplinary assessment. Better awareness of ILD among medical dermatologists and close interdisciplinary collaborations are likely to prevent treatment delays improving long-term outcomes.

Long-term clinical course and outcomes of immunoglobulin G4-related lung disease

Background

Immunoglobulin G4-related lung disease (IgG4-RLD) is the pulmonary manifestation of a systemic fibroinflammatory disease characterized by lymphoplasmacytic infiltration with an abundance of IgG4-positive plasma cells. Long-term clinical course and outcomes of IgG4-RLD remain unclear. We aimed to identify clinical characteristics, treatment outcomes, and longitudinal pulmonary function changes in patients with IgG4-RLD according to the radiologic classification.

Methods

Chest computed tomography findings of 37 subjects were classified into five subtypes: solid nodular, bronchovascular, alveolar interstitial, round ground glass opacity, and alveolar consolidative. Radiologic treatment outcomes and longitudinal pulmonary function changes were compared among the different radiologic subtypes.

Results

The mean age of the subjects was 55.6 years, and 78.4% were male. Among the five radiologic subtypes, alveolar consolidative and solid nodular type were most common, accounting for approximately 29.7% each of the total cases. Prednisone with or without azathioprine was administered to 31 patients (median treatment duration 14 months). In the treated patients, serial images showed complete response or partial response in 77.4%. However, relapse was documented in 25.0% of those who showed complete or partial response. In patients whose longitudinal lung function data were available (n = 20), the lung function was found to be stable during follow-up. Alveolar consolidative type showed the highest complete response rate, whereas alveolar interstitial type showed the lowest response rate, either complete or partial.

Conclusions

Most patients showed a favorable outcome with regards to radiologic improvement and maintenance of pulmonary function; however, the response differed according to the radiologic subtype.