A major strength of this study is to demonstrate the feasibility of technically demanding repetitive WLL in a very small child over extended periods of time. Although therapeutic WLL is generally accepted as the established treatment option for PAP in adults, its optimal method, frequency of application and many other details are currently not known in infants or children. Here we show that consecutive lavages via a small catheter located in a main stem bronchus ( Figure 3A) can be used to efficiently remove accumulated surfactant from the alveolar space in a very small child. Furthermore we show that it is helpful to monitor efficacy of the washing procedure by determination of proteins and lipids removed from the lungs [15] . These measurements allowed us to demonstrate only a marginal, but not clinically significant increase in the removal of surfactant material from the lungs, by the use of PFC for lavage. In a case report on an infant with alveolar proteinosis due Niemann Pick disease the usage of PFC was recently shown not to be of benefit as well [21] .