Isolated congenital spleen agenesis: a rare cause of chronic thromboembolic pulmonary hypertension in an adult.

This report describes a case of isolated congenital spleen agenesis complicated by chronic thromboembolic pulmonary hypertension (CTPH) in a 44-year-old female patient. The patient had increasing exertional dyspnoea and thrombocytosis. An echocardiogram showed severe pulmonary hypertension and right ventricular hypertrophy, and contrast-enhanced chest CT revealed multiple thromboemboli within both pulmonary arteries. A perfusion lung scan demonstrated multiple segmental defects and no spleen was detected by abdominal CT, ultrasonography or scintigraphy. Comprehensive clinical examinations disclosed no evidence of a thrombus elsewhere or of an associated malformation such as a cardiac anomaly. Anticoagulation therapy was started, and a perfusion lung scan revealed partial improvement of the hypoperfusion in the right lower lobe. However, repeat echocardiography showed the pulmonary hypertension persisting for 1 year. The multiple segmental defects in the perfusion lung scans were also persistent. Collectively, a diagnosis of CTPH with isolated congenital spleen agenesis was established. This is the first documented case of CTPH in an adult with isolated congenital asplenia. Although congenital spleen agenesis is a rare condition, this case report suggests that this possibility should be considered when a diagnosis of CTPH and thrombocytosis is made.