Breast hamartoma is a benign breast lesion involving a localized proliferation of normal breast elements. It has a characteristic appearance on imaging studies.


Synonyms: adenolipoma, lipofibroadenoma, fibroadenolipoma


Size: may measure up to 18 cm, but usually is around 3-4 cm


Age: anytime after puberty, but it is most commonly seen in women in their 40's.


It may occur as part of Cowden's syndrome (multiple hamaratoma syndrome).


Features on clinical examination depend on size and composition.

(1) The lesion may or may not be palpable. Lesions with more fibrous tissue are firmer, while those with more adipose tissue are softer.

(2) It may be asymptomatic or associated with pain, intermittent swelling, localized inflammation, nipple discharge or nipple retraction.


Features on imaging studies:

(1) unilateral, round or oval

(2) sharply demarcated ("encapsulated")

(3) variable degree of opacity, depending on the relative amount of fat:

(3a) It may have a homogeneous density only slightly different from that of the surrounding breast.

(3b) It may show focal areas of parenchymal distortion or a mixed density ("slice of salami").

(4) calcification is usually absent; if present it should have a pattern suggestive of benign disease


Features on pathologic examination:

(1) well-circumscribed with a fibrous pseudo/capsule. The lesion can usually be easily shelled out by the surgeon.

(2) clefts and fronds are not prominent on cross section

(3) admixture of adipose tissue, fibrosis, ducts and lobules

(4) pseudo-angiomatous stromal hyperplasia (a network of inter-anastomosing slit-like spaces lined by flattened cells negative for Factor-VIII related antigen) may be present

(5) fibrocystic changes (cysts, apocrine metaplasia), adenosis and epithelial hyperplasia may be present

(6) infrequently a carcinoma in-situ or carcinoma may arise within a hamartoma

(7) infrequently stromal giant cells or focal ossification may be present


Differential diagnosis:

(1) lipoma

(2) fibroadenoma (stroma more cellular and may lack breast lobules)

(3) phylloides tumor

(4) fibromatosis


Criteria for excision:

(1) troublesome breast asymmetry

(2) pain or discomfort

(3) mammographic changes suspicious for malignancy


About 5-10% of excised hamartomas will recur.


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