Unilateral Left-Sided High-Altitude Pulmonary Edema Following Rapid Ascent to a City in the Himalayas.

High-altitude pulmonary edema (HAPE) is a medical emergency commonly observed in people ascending to altitudes above 9000 ft. The condition predominantly presents with bilateral clinical and radiological findings. In rare cases, where unilateral lung involvement is seen, a right lung predilection is usually noted. We present a case of HAPE with unilateral left lung involvement in a young man upon reintroduction to a high-altitude area. He presented with dyspnea at rest and was found to have severe hypoxemia and tachycardia. Clinical and radiological evidence showed unilateral left lung findings. After excluding other plausible causes, it was concluded to be a case of HAPE. Following treatment, his symptoms resolved, and he was discharged on the fifth day after admission. This case highlights the necessity of awareness related to the uncommon presentations of HAPE since this condition can be completely reversed with a good patient outcome if suspected and treated early.