Breast hamartoma: A report of 14 cases of an under-recognized and under-reported entity

• Mammary hamartoma is a rare benign lesion accounting for approximately 4.8% of all benign breast masses.
• There are several variants depending on the composition of glandular and fibroadipose elements including adenolipoma, fibroadenolipoma, and myoid hamartoma.
• Histologically the lesions show a haphazard admixture of benign mammary glandular tissue, fat, and fibrous strands present in varying proportions.
• Breast hamartomas are rarely associated with malignancies.
• Excision of hamartoma is considered curative; though recurrence is seen in 8% of cases.

ObjectivesMammary hamartoma is a rare benign lesion accounting for approximately 4.8% of all benign breast masses. It is often underdiagnosed and therefore is underreported mostly due to lack of awareness of the characteristic clinical and histological features. Raising awareness of this poorly recognized benign entity is of utmost significance as it clinically mimics other breast tumors including both benign and malignant ones. This study is to report and present our experience of breast hamartomas from Johns Hopkins Aramco Healthcare in the Eastern province of Saudi Arabia from which there have not been previous studies in literature.MethodA retrospective review of our pathology files was done from 1994 to 2014 for cases diagnosed as breast hamartoma during this 20 year period.ResultsA total of 14 cases with diagnosis of breast hamartoma were identified in our institute. Histologically the lesion is mostly sharply demarcated showing a mixture of varying proportions of fibrous, adipose, and glandular tissue. 13 cases were seen in females (93%) and only one rare occurrence in a male patient (7%). The age ranges quite vastly from 18 to 51 years (mean 33 years). Two-third of these lesions were seen involving the right breast (9 cases/64.3%) and only one-third in the left side (5 cases/35.7%). 13 out of 14 patients had a well circumscribed lesion (92.9%) while only 1 case showed irregular borders (7.1%). The size varied from 1.4 to 9.5 cm. Three cases (21.4%) showed evidence of myoid differentiation, a histopathologic variance which is important to identify however has no clinical significance. 3 cases had associated epithelial ductal hyperplasia of the usual type varying from mild (2 cases) to moderate (1 case); with two of these cases exhibiting additional features of fibrocystic mastopathy including adenosis, apocrine metaplasia, and cyst formation. None of our cases showed any malignancy or pseudoangiomatous stroma hyperplasia (PASH).