What you see is not always what you get: Radiographic-pathologic discordance among benign breast masses

The differential diagnosis for benign breast masses is broad and ranges from common lesions like fibroadenomas to rare masses like breast hamartomas. Fibroadenomas are proliferative benign masses made up of fibroglandular tissue. Hamartomas are neoplasms comprised of different tissues that are endogenous to the area where they originate. Breast hamartomas specifically, are rare, benign slow growing tumours comprised of fibrotic stroma, adipose, glandular tissue, and epithelial components. Both lesions are painless, firm, and are typically palpable on clinical exam. Given their similarities in composition, diagnosing these masses can be challenging, but may be confirmed with ultrasonography, mammogram, computed tomography, magnetic resonance imaging, or via histological specimen. Once diagnosed, surgical excision is the preferred treatment option. We present a 33-year-old woman with a large left breast mass that gradually increased in size and provide a review of the current literature regarding the challenge of distinguishing between breast fibroadenomas and hamartomas.