Pulmonary adenocarcinoma with psammoma bodies is associated with a specific endobronchial ultrasound pattern and a high prevalence of actionable driver mutations

Introduction: Pulmonary adenocarcinoma with psammoma bodies (PAPBs) is a rare histological variant whose association with a high prevalence of targetable mutations has been suggested by scant literature reports describing small series. We aim to describe the endobronchial ultrasound (EBUS) pattern and the molecular profile by next-generation sequencing of an Italian series of patients with PAPBs.Material and methods: Over a 8-year period (2012-2019), we identified 15 patients with a very uncommon endobronchial ultrasound (EBUS) heterogeneity pattern characterized by the presence of multiple to countless, punctate non-shadowing foci ("starry sky" sign) which were not evident at CT and corresponded to psammoma bodies at pathological examination. The clinical, radiological, pathological and molecular findings of these patients were retrieved and analyzed.Results: Pathological examination of the EBUS-TBNA specimens revealed malignancy (12 pulmonary adenocarcinoma, 2 breast carcinoma, 1 colonic carcinoma) and showed the presence of psammoma bodies in all of the 15 patients with the starry sky sign. Among the 12 patients with pulmonary adenocarcinoma with psammoma bodies, female sex (8/12, 66.7 %) and never-smoking habit (6/12, 50 %) were prevalent. Molecular tumor profiling using the OncomineTM Focus DNA and RNA fusion panels was successfully performed in 11/12 patients and revealed 10 genetic alterations (BRAF mutation, 4; EGFR mutation, 2; ALK rearrangement, RET rearrangement, PIK3CA mutation, CDK4 amplification 1) in 7 patients (63.6 %).Conclusion: The present series suggests that pulmonary adenocarcinoma with psammoma bodies is associated with a readily identifiable EBUS pattern and with a high prevalence of different, often uncommon and actionable, driver mutations.