Spherocytosis and pulmonary hypertension coincidental occurrence or causal relationship?

A report is given on a 59 yr old man with hereditary spherocytosis and progressive shortness of breath on exertion, due to severe pulmonary hypertension and cor pulmonale. An open lung biopsy was performed in order to exclude all known aetiologies of secondary pulmonary hypertension. Pathological examination revealed in situ thrombosis and asymmetric fibromuscular hyperplasia of small- and medium-sized pulmonary arteries. Both primary pulmonary hypertension and hereditary spherocytosis have a low incidence in the general population and their simultaneous occurrence has not been reported previously; the possibility that this was due to a causal relationship and not to coincidence cannot be ruled out, in view of some similarities with pulmonary hypertension complicating sickle cell anaemia.