Erythromelalgia Caused by Polycythemia Vera Combined With Primary Aldosteronism

A 61-year-old woman with a history of primary aldosteronism caused by unilateral hyperplasia of the adrenal gland presented with a 2-week history of redness and severe pain in the right thumb and thenar regions. She had initially visited a dermatologist and was diagnosed with cellulitis and treated with cefditoren pivoxil for 5 days, but there was no improvement. The pain worsened and was accompanied by a burning sensation. The dermatologist prescribed famciclovir for 5 days owing to suspicion of herpes zoster. The patient was then referred to our department because her symptoms persisted. Physical examination showed no abnormalities other than the redness in the right thumb and thenar regions and spontaneous moderate pain present throughout the right thumb. Investigations revealed normal blood chemistry and coagulation factor levels, except for elevated haemoglobin (18.2 g/dl). Further investigations revealed an erythropoietin level of 2.3 IU/ml and Janus kinase 2 mutation. Hence, we diagnosed the patient with erythromelalgia caused by polycythemia vera. In this report, we discuss the treatment of polycythemia causing erythromelalgia, and the aetiology of primary aldosteronism and polycythemia vera.