ABSTRACT
PURPOSE: Many different conditions result in pleural effusions (PEs) and making the differential diagnosis of PE is difficult. The purpose of the present study was to document the change of incidence and compare the etiologies of PEs with regards to age, the sidedness and characteristics of PE. METHODS: During the 10-year period from 1986 to 1995, thoracentesis was performed in 197 children with PEs at Seoul National University Children's Hospital. The hospital records of these children were reviewed, and radiologic findings and laboratory data of PE were analyzed. RESULTS: The distribution of the etiologies of PEs changed with the declining incidence of tuberculous PE. Infectious PE was the leading cause of PE in each age group. The most common etiology of infectious PE in children aged less than 3 years was bacterial PE, aged 3 to 6 years mycoplasma PE, and aged more than 6 years tuberculous PE. Malignant PE was the second most frequent cause of PE and the incidence of it was marked in children aged 3 to 6 years. Non-Hodgkin lymphoma was the most frequent cause of malignant PE and Burkitt lymphoma and leukemia were the next two leading causes of it. The sidedness of the PE was not helpful in differentiating various types of PEs. Measurements of the pleural fluid protein & glucose were not useful either. Bacterial PE presented the highest LDH activity. Infectious PE presented higher pleural fluid leukocyte count than any other type of PE, and bacterial PE was most prominent in this respect. The PE polymorphonuclear leukocyte % was marked in bacterial PE and the PE lymphocyte % in tuberculous PE. CONCLUSION: The distribution of the etiologies of PEs seems to have changed. Age, LDH, leukocyte count and differential cell count of PE were helpful in differentiating various types of PEs.