Clinical Analysis Of Patients With Dermatomyositis/Polymyositis Complicated Interstitial Lung Disease

Dermatomyositis (DM) and polymyositis (PM) are the idiopathic inflammatory diseases of soriated skeletal muscle. A characteristic skin rash is present in DM. Besides skin and muscle, they can cause multiple organs and systems lesion. Lung, which has rich connective tissue and blood supply, is the mostly involved organ. Interstitial lung disease (ILD) is the most common involvement. Diagnosing the disease at the early stage and offering the reasonable therapy may help to improve the prognosis and quality of life.The etiology of DM/PM complicated ILD is complex and still not clear so far. Current thoughts relate to the disorder of humoral immune and cellular immune. Pulmonary fibrosis is a slow and complicated course which includes the participation of various cells, cytokines and extracelluar matrix (ECM). The balance of promoting and inhibiting fibrotic cytokines decides the occurrence and extent of pulmonary fibrosis. Pathologic unbalance of cytokines and accumulation of ECM can both lead to pulmonary fibrosis. Autoantibodies to aminoacyl transfer RNA synthetases, such as histidyl(Jo-1), threonyl(PL-7), alanyl(PL-12), glycyl(EJ) and isoleucyl (OJ) are all associated with the disease which have an important effect. Additionally, pneumonia caused by esophagus muscle weakness or ventilative deficiency may aggravate the fibrosis. Treatment of costicosteroides and immunosuppressants can also increase the conditional inflammation or lead to drug induced pneumonia.Chest radiographic test, high-resolution computed tomography (HRCT), pulmonary function test are the most common diagnostic techniques. The inflammatory lung pattern, such as ground-glass attenuation, reticulation, nodular change can be discovered on HRCT. Honeycombing change can be detected in end stage patients. Radiological technique is capable of detecting secondary lung lobar disease via HRCT. The widely uses of HRCT can help to diagnosis on early stage and supervising the development of the disease. Furthermore, serum tests including laminin(LN), precollogentype III(PcIII), serum surfactant protein D(SP-D), serum KL-6 has been the international focus recently. KL-6 level is considered to be a serum factor correlated directly with alveolar lesion. It has been proved that DM/PM-ILD patients elevated significantly , which was about 7 times higher than normal group. The sensitivity and specificity of serum abnormal KL-6 levels for the disease were 90.9% and 80.6%. The methods above provides available prospect to ILD in DM/PM.How to cure the DM/PM-ILD patients is still a very difficult problem in clinical practice. Since the side function of drugs is a lot and therapeutic efficacies are limit, whether treating or not should due to the evaluation of the clinical manifestation, pulmonary function and the degree of fibrosis. The basic target of treatment includes: to eliminate the primary disease causing pulmonary fibrosis and control the inflammation; to inhibit the proliferation and activation of cells and induce necrosis; to antagonize the synthesis and resolve of ECM. Costicosteroides and immunosuppressive drugs are still the major methods in DM/PM-ILD. Costicosteroides can prevent neutrophils and lymphocytes assembling to lung, reduce the production of immune complex, inhibit the secreting function of macrophages and disturb the adherence of neutrophils on the endotheliums. Through the mechanisms above, costicosteroides are able to suppress the inflammation and prevent pulmonary fibrosis. immunosuppressive drugs includes cyclophosphamide, methotrexate, azathioprine, cyclosporine and so on. Low dose of costicosteroides combined immunosuppressive drugs are generally accepted by many patients.This article is a retrospective clinical observation. 78 patients were divided into three groups which were DM/PM with ILD, DM/PM without ILD, idiopathic pulmonary fibrosis(IPF) and try to analyze the clinical feature of DM/PM-ILD and summarize the therapeutic efficacy.The result display:1. Fifteen DM/PM patients (31.15%) developed ILD.2. Female to male ratio of DM/PM was 2.17:1 while the data was 0.54:1 in IPF. The average age in IPF was significantly higher than DM/PM. The average smoking period was 22.44±10.56 years in IPF compared 10.53±2.15 in DM/PM. The respiratory symptoms and signs were more common in IPF group. The Velcro rales and acropachy occurrence were more than DM/PM group. The reticulation was the most common change in HRCT between the two groups. The frequency of pleural involvement in DM/PM group was significantly higher than IPF group (P<0.05).3. Arthralgia and the occurrence of anti-Jo-1 antibodies were found more often in patients with ILD than in those without. Dysphagia and the higher level of ESR, LDH, had statistical significance between the two groups. The reduction of serum CK in the ILD group was smaller than the other group via the corticosteroid treatment. In the nineteen patients with ILD, ten, five and two cases had experienced improvement, little changing and death respectively.Conclusions:1. The frequency of ILD is high among DM/PM, which reaches to 31.15%. The data seems increasing annually.2. IPF always occurs in senile males and may relate to the length of smoking period. DM/PM-ILD always occur in young and middle-aged females. It has no obvious relevance with smoking.3. The symptoms and signs of DM/PM-ILD were not typical compared with IPF. Pleural involvement on HRCT suggests that we should pay attention to the possibilities of DM/PM-ILD.4. Arthralgia, the occurrence of anti-Jo-1 antibodies, higher values of ESR, LDH may be considered as the predictive factors of ILD.5. Costicosteroides can reduce serum CK of most DM/PM patients. It seems costicosteroides is more effective in the patients without ILD.