ECMO Support in Paraneoplastic Pemphigus With Respiratory Failure: A Case Report With Immune Cell Monitoring

Paraneoplastic pemphigus (PNP) is a life‐threatening autoimmune blistering disease with a mortality rate of 70%–90%, driven largely by respiratory complications such as bronchiolitis obliterans. Managing respiratory failure in these patients remains exceptionally difficult. We report a 33‐year‐old male with follicular dendritic cell sarcoma who developed severe PNP complicated by type II respiratory failure and obstructive bronchiolitis requiring veno‐venous extracorporeal membrane oxygenation (ECMO) support. The patient's PNP skin lesions improved during a treatment course that included ECMO support, intravenous immunoglobulin (IVIG), immunosuppressants, hemodialysis, and plasma exchange. Serial immune cell subset monitoring showed a rising CD4/CD8 ratio (+94.8%) and Helper T cells (+33.8%), alongside declining NK cells (−48.2%), T lymphocytes (−17.7%), and Suppressor T cells (−31.6%). This case illustrates successful short‐term management of severe PNP with respiratory failure through multidisciplinary care, including ECMO. Because multiple interventions were administered concurrently, improvement cannot be attributed to any single therapy. Serial immune‐cell monitoring may help track treatment response in this setting.