Simultaneous occurrence of multiple aetiologies of polycythaemia: renal cell carcinoma, sleep apnoea syndrome, and relative polycythaemia in a smokerwith masked polycythaemia rubra vera

A 58 year old male heavy smoker presented with intracranial haemorrhage and erythrocytosis. Four aetiologies of polycythaemia-polycythaemia rubra vera (PRV), renal cell carcinoma, sleep apnoea syndrome, and relative polycytha emia-were found to be associated with the underlying causes of erythrocytos is. He did not fulfill the diagnostic criteria for PRV at initial presentat ion, but an erythropoietin independent erythroid progenitor assay identifie d the masked PRV, and the low postphlebotomy erythropoietin concentration a lso suggested the likelihood of PRV evolution. This case demonstrates that a search for all the possible causes of erythrocytosis is warranted in pati ents who already have one aetiology of polycythaemia.