PDCD1 and pulmonary arterial hypertension: Pulmonary hypertension (PH) triggered by ICI, though infrequently documented, has come to be recognized and regarded with greater importance in recent years owing to its association with life-threatening outcomes.<h4>Case presentation</h4>We report a case of a 65-year-old male who developed severe pulmonary arterial hypertension (PAH) following treatment with the programmed cell death protein 1 inhibitor tislelizumab.