High altitude pulmonary edema (HAPE) is a life-threatening complication of high altitude stay, which may occur above altitudes of 2500 m. This is a case report of a healthy 41-year-old man, presenting with recurrent HAPE at moderate altitude. Medical work-up revealed an idiopathic pulmonary artery hypertension (PAH), and specific vasoactive treatment was started. Despite treatment with an endothelin receptor antagonist, the patient deteriorated clinically. Subsequent medical reevaluation showed a significant progress of mediastinal lymphadenopathy. Due to the histological proof of sarcoidosis, the initial diagnosis of PAH had to be changed to sarcoidosis-related pulmonary hypertension. Initiation of immunosuppressive therapy with corticosteroids led to significant and clinically relevant decrease in pulmonary artery pressure, even allowing episodes of asymptomatic re-exposure to moderate altitude. This case describes HAPE as first manifestation of a sarcoidosis-related pulmonary hypertension with a very unusual and early presentation of the underlying disease in an apparently healthy mountaineer.