This article reports the case of an adolescent patient presenting with recurrent epistaxis and orthostatic hypoxemia. Chest imaging revealed multiple bilateral pulmonary nodules of varying sizes and mixed densities. The presence of intrapulmonary right-to-left shunting was confirmed through bubble contrast echocardiography, pulmonary first-pass perfusion imaging, and the pure oxygen inhalation formula method. Whole-genome sequencing identified a mutation in the SMAD4 gene, and subsequent family analysis confirmed the diagnosis of hereditary hemorrhagic telangiectasia (HHT). Currently, there is no international consensus on the management of such rare presentations. Based on relevant case reports in the literature, the patient was empirically treated with a combination of amlodipine and thalidomide. After one year of follow-up, significant improvement in hypoxemia was observed. The diagnostic and therapeutic process of this case offers valuable insights for the clinical management of patients with mixed-type PAVMs caused by HHT.