Immunocytochemical detection of Napsin-A in pulmonary alveolar proteinosis. A report of two cases

We have observed intense Napsin-A expression in the globular bodies seen in BAL samples from patients with PAP. We believe that it is a useful marker for confirming this diagnosis, especially in the absence of electron microscopy or surfactant-specific antibodies. Its application to cytological samples increases diagnostic accuracy, allowing, in an appropriate clinical and imaging context, a more precise diagnosis.