Value of serum YKL-40 in the diagnosis of anti-MDA5-positive patients with dermatomyositis complicated with severe pulmonary injury / 北京大学学报(医学版)

OBJECTIVE@#To investigate the value of serum and bronchoalveolar lavage fluid (BALF) chitinase-3-like-1 protein (YKL-40) in the diagnosis of anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis (DM) patients complicated with serious pulmonary injury, including rapidly progressive interstitial lung disease (RP-ILD) and pulmonary infection.@*METHODS@#Anti-MDA5 antibodies positive patients with DM who were hospitalized in the Department of Rheumatology of China-Japan Friendship Hospital from 2013 to 2018 were involved in this study. Demographic information, clinical, laboratory and imaging data were retrospectively collected. ELISA was used to detect the serum and BALF levels of YKL-40. The receiver operating characteristic (ROC) curve was drawn, and the area under ROC curve (AUC) was used to evaluate the diagnostic value of serum YKL-40 for pulmonary injury.Interstitial lung disease (ILD) was confirmed by chest high-resolution CT (HRCT). RP-ILD was defined as progressive respiratory symptoms such as dyspnea and hypoxemia within 3 months, and/or deterioration of interstitial changes or appearace of new pulmonary interstitial lesions on chest HRCT. Pulmonary infection was considered as positive pathogens detected in qualified sputum, blood, bronchoalveolar lavage fluid or lung biopsy specimens.@*RESULTS@#A total of 168 anti-MDA5-positive DM patients including 108 females and 60 males were enrolled in the study. Of these patients, 154 had ILD, and 66(39.3%) of them presented RP-ILD. Seventy patients with pulmonary infection were confirmed by etiology. In the patients with RP-ILD, 39 (59.1%) of them were complicated with pulmonary infection. While only 31 cases(30.4%) had pulmonary infection in the non-RP-ILD patients. The incidence of pulmonary infection in the patients with RP-ILD was significantly higher than that of those with non-RP-ILD (P < 0.001). The serum YKL-40 levels in the RP-ILD patients with pulmonary infection were the highest compared with RP-ILD without pulmonary infection, non-RP-ILD with pulmonary infection and non-RP-ILD without pulmonary infection groups among all the patients [83 (42-142) vs. 42 (21-91) vs. 43 (24-79) vs. 38 (22-69), P < 0.01].The sensitivity, specificity and AUC of serum YKL-40 in the diagnosis of RP-ILD complicated with pulmonary infection were 75%, 67%, and 0.72, respectively. The AUC of diagnosed of anti-MDA5 positive DM patients complicated with RP-ILD and pulmonary infection was higher than that of patients complicated with only RP-ILD and only pulmonary infection (0.72 vs. 0.54 and 0.55, Z=2.10 and 2.11, P < 0.05).@*CONCLUSION@#The prognosis of anti-MDA5-positive DM patients with RP-ILD and pulmonary infection were poor. Serum YKL-40 level can be used as a helpful tool for the diagnosis of coexistence of these conditions in the patients.

Spontaneous pneumomediastinum complicating interstitial lung disease, associated with clinically amyopathic dermatomyositis and positive anti-MDA5 antibodies / Neumomediastino espontáneo como complicación de enfermedad pulmonar intersticial, asociada con dermatomiositis clínicamente amiopática y anticuerpos anti-MDA5 positivos

Abstract Clinically amyopathic dermatomyositis comprises a special group of patients within the spectrum of dermatomyositis characterized by the presence of typical skin lesions, minimal or absent muscle involvement, and increased risk of interstitial lung disease. The antibodies directed against the protein encoded by melanoma differentiation-associated gene 5 (MDA5) are present in a significant proportion of patients with clinically amyopathic dermatomyositis, who develop rapidly progressive interstitial lung disease, with high mortality and frequently complicated by the onset of spontaneous pneumomediastinum. A case is presented of an African patient with anti-MDA5 positive clinically amyopathic dermatomyositis and interstitial lung disease with tomography pattern of organizing pneumonia who developed spontaneous pneumomediastinum during its clinical course.

Resumen La dermatomiositis clínicamente amiopática comprende un grupo especial de pacientes dentro del espectro de la dermatomiositis, caracterizados por la presencia de lesiones cutáneas típicas, compromiso muscular mínimo o ausente y riesgo aumentado de enfermedad pulmonar intersticial. Los anticuerpos dirigidos contra la proteína codificada por el gen asociado con la diferenciación del melanoma 5 (MDA5), están presentes en una proporción importante de pacientes con dermatomiositis clínicamente amiopática, los cuales desarrollan enfermedad pulmonar intersticial rápidamente progresiva, con elevada mortalidad y que se complica frecuentemente con la aparición de neumomediastino espontáneo. Presentamos el caso de una paciente de origen africano con dermatomiositis clínicamente amiopática anti-MDA5 positiva y enfermedad pulmonar intersticial con patrón tomográfico de neumonía organizada, que desarrolló neumomediastino espontáneo durante su evolución.