RT Journal Article SR Electronic T1 Challenging cases in PH JF European Respiratory Review JO EUROPEAN RESPIRATORY REVIEW FD European Respiratory Society SP 19 OP 23 DO 10.1183/09059180.00010205 VO 16 IS 102 A1 M. M. Hoeper A1 F. Laenger YR 2007 UL http://err.ersjournals.com/content/16/102/19.abstract AB The requirement for a timely diagnosis of pulmonary arterial hypertension (PAH) to maximise the benefits achieved with appropriate therapy is hampered by the insidious nature of the disease and consequently the late presentation of the majority of patients. Therefore, it is critical to maintain a high index of suspicion in cases of unexplained dyspnoea and to employ a structured and systematic diagnostic strategy. Pulmonary hypertension (PH) has been classified clinically into PAH, PH associated with left heart diseases, PH associated with hypoxaemia or disorders of the respiratory system, PH caused by chronic thrombotic or embolic disease and PH caused by disorders of the pulmonary vasculature, such as sarcoidosis. These different classes of diseases may have similar presentations despite differing physiologies and aetiologies. Moreover, in some cases, incorrect diagnosis and instigation of an inappropriate course of action can have serious consequences. This paper illustrates two particularly challenging clinical cases that can be encountered in patients with pulmonary hypertension.