Incidental Gynecomastia on Thoracic Computed Tomography in Clinical Practice: Characteristics, Radiologic Features, and Correlation With Possible Causes in South Korean Men.

Gynecomastia is a common incidental finding on thoracic computed tomography (CT). This study aimed to retrospectively determine the prevalence, imaging characteristics, and possible causes of incidental gynecomastia on thoracic CT. Records of male patients who underwent thoracic CT in 2015 were reviewed. The size and morphologic types (nodular, dendritic, and diffuse) were recorded for patients with breast glandular tissue larger than 1 cm, and the cutoff value of gynecomastia was defined as 2 cm. Additionally, the possible causes of gynecomastia obtained by reviewing patients' charts were recorded. CT-depicted gynecomastia was identified in 12.7% (650 of 5,501) of patients. The median size of the breast glandular tissue was 2.5 cm (interquartile range 2.2-3.1), and 36.8% of patients (239 of 650) had unilateral gynecomastia. The age distribution provided a bimodal pattern with two peaks in the age groups from 20 to 29 years old and greater than 70 years old. Chronic liver disease (CLD; p < .001), all stages of chronic kidney disease (CKD; p < .001), and medications (p = .002) were significantly associated with gynecomastia. Gynecomastia did not correlate with body mass index (p = .962). The size of breast glandular tissue was identified to be correlated with the morphologic type of breast tissue and the severity of CLD or CKD. The prevalence of incidental gynecomastia seen on thoracic CT was 12.7%. CT-depicted gynecomastia is not associated with obesity but with CLD, CKD, and medications. When gynecomastia is detected on CT, further evaluations and management might be required for patients with a treatable cause.