Purpose or Case Report: To determine CT imaging features of benign intra-pulmonary lymph nodes in pediatric patients.
Methods & Materials: A retrospective medical record review was performed to identify thoracic CT studies from pediatric solid cancer patients (≤ 18 years) with histologically confirmed intrapulmonary lymph nodes between February, 2005 and October, 2015. CT characteristics of intrapulmonary lymph nodes (including size, shape, margin, location, interval growth) and patient’s history of metastasis were independently evaluated by two radiologists. CT features most predictive of an intrapulmonary lymph node in pediatric patients were analyzed using summary statistics and multiple logistic regression models.
Results: There were 33 pathology-confirmed benign intrapulmonary lymph nodes from 24 pediatric patients (15 boys and 9 girls; mean age = 14.1 years; age range 1 years to 18.2 years). Average size of intrapulmonary lymph nodes was 3.5 mm (1.3 mm to 7.8 mm). All triangular-shaped nodules (100%, 21/21) were found to be benign intrapulmonary lymph nodes (B = 4.6, p=0.00024). Other shapes (7 oval (21%), 3 round (9%), and 2 trapezoidal (6%)) were not statistically significant predictors of a benign intrapulmonary lymph node. All intrapulmonary lymph nodes were smoothly marginated and solid. There was symmetric distribution of the sampled intrapulmonary lymph nodes (19 (58%) in the right and 14 (42%) in the left). Intrapulmonary lymph nodes were pleural-based in 14 patients (43%), peri-fissural in 10 patients (30%), and parenchymal in 9 (27%) patients. Interval growth (B = -3.4, p = 0.0017, uni-variate model) and patient’s history of metastasis (B = -2.2, p = 0.015) were statistically significant negative predictors against benign lymph nodes.
Conclusions: In pediatric patients, benign intrapulmonary lymph nodes are sub-centimeter in size (average size = 3.5 mm), well-marginated, and appear solid on CT. In particular, triangular shape of a nodule strongly predicted benign intrapulmonary lymph node, while interval growth and patient’s history of metastasis predicted against a benign intrapulmonary lymph node.