A breast hamartoma: A typical picture of ‘‘breast with in breast’’

A 40-year-old female presented to surgery department with complaint of right breast lump since 6 months without pain. No significant history for breast malignancy was found. On examination, firm non-painful lump was palpated causing breast asymmetry. Overlying skin appeared unremarkable. Patient was then referred to radiology department for sono-mammographic evaluation.

On full field digital (FFD) mammography, heterogeneously dense (Type C) breasts are found with a well-defined heterogeneous mixed radiodensity (similar to surrounding breast parenchyma including fatty radiolucent areas) lesion of size 8.3 x 10.4 x 9.3 cm compressing and displacing surrounding breast parenchyma with surrounding typical complete and thin fibrous pseudocapsule in lower central part of right breast without any micro or macro calcifications which gives it typical ‘‘breast with in breast appearance’’ and hence diagnosed as breast hamartoma – BIRADS 2 (Figures 1a and 1b). On ultrasound correlation, it shows a large, well-defined oval lesion with mixture of hypo and hyperechoic tissue following breast echogenicity. No evidence of abnormally increased vascularity / posterior acoustic shadowing or enhancement / duct ectasia / axillary lymphadenopathy was noted (Figure 2).

Hamartoma which is also known as fibroadenolipoma, are uncommon (4–8% of all benign tumours of breast) but typical benign tumour of the breast containing glandular epithelium, adipose tissue, and fibrous tissue in variable proportions. They are typically seen in middle-aged women older than 35 years of age and characterized by slowly growing and variable-sized mass usually measuring 10–12 cm in diameter, which may occupy almost the entire breast [1]. Most commonly breast hamartomas are asymptomatic, while others present by painless soft breast lump or unilateral breast enlargement. Components of hamartomas are similar to normal component of breast tissue hence named hamartoma. Even fibrocystic changes can be seen in it. The other name fibroadenolipoma refers to a benign proliferation of fibrous, glandular and fatty tissue surrounded by a thin capsule of connective tissue, which is actually a pseudo capsule made up of breast parenchyma that has been displaced by the mass [2]. On gross examination, hamartomas are typically well-defined, sometimes lobulated with smooth surface and an often rubbery greyish-white to yellow cut surface, resembling a fibroadenoma or lipoma. The two common variants of breast hamartoma are adenolipoma and chondrolipoma. Chondrolipoma variant consists of fatty tissue with mature lobules of cartilage with a well-circumscribed mass [6]. Adenohibernoma and myoid hamartoma are very rare variants, where adenohibernoma contains brown adipose tissue interspersed with glandular tissue [7], while myoid hamartoma contains well-differentiated adipose tissue, stromal components, areas of smooth muscle fibres and glandular tissue [8]. The risk of malignancy in hamartoma is very rare and develops from the glandular component. Rarely present in coexistence with lobular carcinoma and invasive ductal carcinoma [3-5]. Typical imaging features can give definitive diagnosis as in our case. Although fine-needle aspiration cytology (FNAC) and core needle biopsy are accurate for diagnosing most of the breast lesions, in cases of hamartoma both may be non-specific as they reveal normal breast tissue components and hence full excision biopsy is usually recommended. Follow-up or if symptomatic, simple lumpectomy is a treatment option in hamartoma without any complications.