Cytologic Evaluation of Positron Emission Tomography-Computed Tomography-Positive Lymph Nodes Sampled by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: Experience at a Large Cancer Center.

CONTEXT.­: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is routinely used to evaluate mediastinal lymph nodes (LNs), especially for cancer staging. There are limited large studies evaluating the cytologic, radiologic, and clinical features of 18F-fluorodeoxy glucose positron emission tomography-computed tomography-positive (PET-CT+) LNs. OBJECTIVE.­: To compare cytologic, radiologic, and clinical features of PET-CT+, cytology-malignant (PET-CT+/Cyto+) and PET-CT+, cytology-benign (PET-CT+/Cyto-) LNs. DESIGN.­: The pathology database was searched for cases of mediastinal LNs obtained by EBUS-TBNA from January 1, 2015 to December 31, 2015. The cytologic, radiologic, and clinical features were collected for all PET-CT+ LNs. RESULTS.­: Of 2267 mediastinal LNs obtained by EBUS-TBNA during this period, 577 LNs met the criteria. Of the latter, 263 (46%) were PET-CT+/Cyto+ and 314 (54%) were PET-CT+/Cyto-. All of the patients with PET-CT+/Cyto+ results had a prior or concurrent diagnosis of malignancy as compared to 89% of patients with PET-CT+/Cyto- results. Of the 224 patients with PET-CT+/Cyto+ LNs, 177 (79%) had metastases from lung primary, 43 (19%) had metastases from nonlung primaries, and 7 (3%) had lymphoma. Average LN size was larger in the PET-CT+/Cyto+ group than in the PET-CT+/Cyto- group (14.6 mm versus 9.58 mm), and mean standardized uptake value in PET-CT+/Cyto+ LNs was higher than that of PET-CT+/Cyto- LNs (10.05 versus 5.99). Significant cytologic findings in PET-CT+/Cyto- cases were necrosis and granulomatous inflammation, including 3 cases with fungal organisms. CONCLUSIONS.­: PET-CT positivity alone was nonspecific for malignancy and insufficient to guide management of patients with mediastinal adenopathy, but specificity could be improved when combined with LN size and standardized uptake value.