Clinical and roentgenological profiles and etiological correlations of encysted pleural effusions

One hundred and thirty-six cases of encysted pleural effusions were studied and investigated to reach an etiological diagnosis. The clinical profile of encysted pleural effusions differed little from that of free pleural effusions. Of the four sites of encystments seen (costoparietal, interlobar, subpulmonic, and mediastinal), costoparietal effusions were the commonest and resulted most often from infections. Interlobar encystments came next in frequency and most often resulted from congestive cardiac failure. Of the various causes of encysted pleural effusions, tuberculosis was the commonest, followed by pyogenic infection and congestive cardiac failure, in this order. Conventional radiographic techniques were adequate in diagnosing most cases of encysted pleural effusions.