Diagnostic Testing
Most patients presenting with gynecomastia do not need a complete workup, which should be reserved for those in whom clinical suspicion for malignancy or other comorbidities is high. In these patients, laboratory tests to consider include a comprehensive metabolic panel, and tests to determine levels of thyroid-stimulating hormone, free thyroxine, free and total testosterone, estradiol, dehydroepiandrosterone sulfate, luteinizing hormone, follicle-stimulating hormone, and prolactin levels. Testicular ultrasound should be considered if bloodwork reveals hormonal dysregulation or if testicular cancer is a concern.
Ultrasound, rather than mammography, is the radiologic modality of choice for diagnosing gynecomastia, which will typically reveal hyperechoic fibroglandular tissue. Mammography and possible fine-needle aspiration or breast biopsy can be considered if breast cancer is a concern. Mammography for the detection of male breast cancer has a reported sensitivity of 92% and specificity of 91%. No established guidelines exist regarding regular mammographic screening for men with gynecomastia; however, if the patient is BRCA (the breast cancer gene) positive, an annual screening mammogram is generally recommended.BRCA screening should be performed only in patients with a strong family history of BRCA-associated cancers (eg, breast, ovarian, prostate, pancreatic cancers, malignant melanoma). Tissue sampling should be obtained only in patients with high suspicion for malignancy. Histology of breast tissue can be obtained by fine-needle biopsy, with gynecomastia usually demonstrating increased subareolar fat, stromal hyalinization, and fibrosis.
Factors that increase the risk of male breast cancer include high circulating estrogen levels, Klinefelter syndrome, family history of breast cancer, presence of BRCA gene mutations, hyperprolactinemia, and history of prior radiation therapy. In a Department of Veterans Affairs study of African American patients, cholelithiasis was a significant predictor of breast cancer in men. Still, no increased risk of breast cancer associated with gynecomastia in men has been demonstrated.