Hamartoma of the breast is an uncommon benign tumor-like nodule, also known as fibroadenolipoma, lipofibroadenoma, or adenolipoma, composed of varying amounts of glandular, adipose, and fibrous tissue. Clinically, hamartoma presents as a discrete, encapsulated, painless mass. Although the pathogenesis of the lesion is not clear, it is thought to result from a dysgenesis rather than a true tumorous process. Some cases have been reported to berelated to a genetic defect called Cowden’s disease. The classic mammographic appearance is a circumscribed area consisting of both soft tissue and lipomatous elements, surrounded by a thin radiolucent zone [119, 120].
On macroscopic examination, hamartomas are typically well-circumscribed lesions with smooth contours. Histologically, the most characteristic appearance is otherwise normal breast and fat tissue distributed in a nodular fashion within a fibrotic stroma that surrounds and extends to between individual lobules and obliterates the usual interlobular specialized loose stroma [119, 121].
There are some issues that should be taken into consideration when evaluating hamartomas. First, this lesion can be very easily underestimated if the clinical finding of a distinct lump or breast asymmetry and the imaging features are not interpreted thoroughly. Second, the pathologist should always be careful about a coincidental epithelial malignancy occurring in the lesion, and the lesion has a potential problem of recurrence. Third, the lesion should be placed in the differential diagnosis of biphasic breast tumors [120, 121].
The current management of hamartomas is surgical removal.