chronic mountain sickness (cms) misdiagnosed as high altitude cerebral edema (hace) at extreme altitude (6400 m/21000 ft)

introduction: chronic mountain sickness (cms) represents a syndrome of secondary polycythemia along with thrombocytopenia, altered hemorheology, pulmonary and systemic hypertension, and congestive heart failure, occurring due to hypobaric hypoxia-anoxia-induced erythropoiesis reported in both native mountain residents and new climbers after prolonged stays at high and extreme altitudes.case presentation: a healthy non-smoker non-drinker reported occipital headache, breathlessness, and insomnia after an uneventful stay of 70 days at 6400 m/21000 ft. his hemoglobin was 21 gm/dl. the patient was diagnosed as having a case of cms with a qinghai cms score >6. therapeutic phlebotomy was performed; 350 ml was drained on two occasions, reducing his hemoglobin to 14.6 gm/dl.conclusion: the altered presentation, difficult diagnosis, evacuation, and long-term management highlighted in this case occurring at 6400 m/21 000 ft in the karakoram himalayas represents the insidious nature of altitude sickness in acclimatized subjects.