title: A New Isolated Mediastinal Lymph Node or Small Pulmonary Nodule Arising during Breast Cancer Surveillance Following Curative Surgery: Clinical Factors That Differentiate Malignant from Benign Lesions.
abstract: OBJECTIVE
  A newly isolated mediastinal lymph node (LN) or a small pulmonary nodule, which appears during breast cancer surveillance, may pose a diagnostic dilemma with regard to malignancy. We conducted this study to determine which clinical factors were useful for the differentiation of malignant lesions from benign lesions under these circumstances.
  
  
  METHODS
  We enrolled breast cancer patients who were presented with a new isolated mediastinal LN or small pulmonary nodule that arose during surveillance, and whose lesions were pathologically confirmed. Tissue diagnosis was made by mediastinoscopy, video-assisted thoracic surgery or thoracotomy.
  
  
  RESULTS
  A total of 43 patients were enrolled (mediastinal LN, 13 patients; pulmonary nodule, 30 patients). Eighteen patients (41.9%) were pathologically confirmed to have a benign lesion (benign group), and 25 patients (58.1%) were confirmed to have malignant lesion (malignant group). Between the two groups, the initial tumor size (p=0.096) and N stage (p=0.749) were similar. Hormone receptor negativity was more prevalent in the malignant group (59.1% vs. 40.9%, p=0.048). The mean lesion size was larger in the malignant group than in the benign group (20.8 mm vs. 14.4 mm, p=0.024). Metastatic lesions had a significantly higher value of maximal standardized uptake (mSUV) than that of benign lesions (6.4 vs. 3.4, p=0.021).
  
  
  CONCLUSIONS
  Hormone receptor status, lesion size, and mSUV on positron emission tomography are helpful in the differentiation of malignant lesions from benign lesions in breast cancer patients who were presented with a new isolated mediastinal LN or small pulmonary nodule during surveillance.
authors.affiliation: Departments of Internal Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Tae-Yong
authors.initials: TY
authors.lastname: Kim
authors.forename: Kyung-Hun
authors.initials: KH
authors.lastname: Lee
authors.forename: Sae-Won
authors.initials: SW
authors.lastname: Han
authors.forename: Do-Youn
authors.initials: DY
authors.lastname: Oh
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
authors.forename: Wonshik
authors.initials: W
authors.lastname: Han
authors.forename: Kyubo
authors.initials: K
authors.lastname: Kim
authors.forename: Eui Kyu
authors.initials: EK
authors.lastname: Chie
authors.forename: In-Ae
authors.initials: IA
authors.lastname: Park
authors.forename: Young Tae
authors.initials: YT
authors.lastname: Kim
authors.forename: Dong-Young
authors.initials: DY
authors.lastname: Noh
authors.forename: Sung Whan
authors.initials: SW
authors.lastname: Ha
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang