OBJECTIVETo analyze the clinical features and investigate the clinical diagnostic methods of hard metal lung disease (HMLD), then provide reference for the diagnostic criteria of occupational HMLD.

METHODSRetrieved the open published case reports associated with HMLD from January, 2000 to June, 2014. Regarding the ages, sex, types and years of work, clinical features and laboratory results for analyzing.

RESULTSCollected 21 clinical cases of HMLD belonged to 6 internal reports and 15 oversea reports. Among them 15 male and 6 female, ages were from 22 to 58, length of service between 1 year and 43 years. Clinical presentations included cough (20 cases), dyspnea on progressive (10 cases), and pulmonary function testing showed a restrictive abnormality. The imaging features presented as bilateral areas of ground-glass attenuation, diffuse small nodules, extensive reticular opacities and traction bronchiectasis. The finding of giant cell interstitial pneumonia (GIP) was almost pathognomonic for hard metal pneumoconiosis. The main pathological findings contained a different levels of lymphocyte, acidophilic cell infiltration, hyperplasia of fibrous tissue and numerous large multinucleated histiocytes which ingested inflammatory cells were admixed with macrophages. 16 cases of the 21 reports showed GIP.

CONCLUSIONSClinical presentations include cough and dyspnea on progressive, and pulmonary function testing show a restrictive abnormality. The imaging features present as bilateral areas of ground-glass attenuation, areas of consolidation, diffuse small nodules, extensive reticular opacities and traction bronchiectasis. The prime pathological findings contain interstitial pneumonia with intra-alveolar macrophages and a large amount of multinucleated histiocytes.