Recurrent pulmonary alveolar proteinosis after lung transplantation: a case series

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder that is characterized by the accumulation of proteinaceous material in the alveoli, leading to dyspnea, pulmonary fibrosis and potentially death. Lung transplantation represents the ultimate treatment option in patients with end-stage or refractory PAP. So far, post-transplant recurrence of PAP has been reported in only three individual cases worldwide. Moreover, there are no reported cases of PAP recurrence post-transplantation in existing patient registries. The detection of recurrent PAP presents a significant challenge after transplantation, given the high prevalence of infectious and immunological conditions in the differential diagnosis. Herein, we report PAP recurrence in three patients who underwent lung transplantation for PAP at our center, confirmed through CT imaging and histological findings. PAP recurrence in two patients with prior autoimmune PAP appears to have a mild clinical course, while a fatal course of PAP recurrence was observed in a patient with prior secondary PAP. Considering all reported cases, PAP recurrence was observed across all forms of pre-transplant PAP, contributing to death in three of the six cases. We call for increased awareness of this potentially underdiagnosed complication in patients undergoing lung transplantation due to PAP.