An unusual cause of acute cor pulmonale--significance of the 'continuous diaphragm sign'.

A patient presented with chest pain and clinical features of acute right heart failure. Initial work up revealed the presence of severe PAH. Acute pulmonary embolism is the commonest and most life-threatening cause for acute cor pulmonale. Even though the clinical picture suggested pulmonary embolism, a subtle sign was missed from the first chest X-ray taken in the emergency department. However on reanalysis the 'continuous diaphragm sign' later guided us towards the diagnosis. Our case represents one of the first reports of a rare etiology for acute cor pulmonale--hypersensitivity pneumonitis. Right ventricular dysfunction was caused by an acute rise in pulmonary artery pressures as well as by the compressive effects of pneumomediastinum. We emphasize the role played by a good quality chest X-ray early in the management of acute chest pain syndromes. However pulmonary embolism should be ruled out conclusively before redirecting attention to less malignant conditions.