Fibroadenoma
Although classified in most textbooks as benign neoplasms, fibroadenomas are best considered as aberrations of normal development: they develop from a whole lobule and not from a single cell, they are very common, and they are under the same hormonal control as the remainder of the breast tissue. They account for about 13% of all palpable symptomatic breast masses, but in women aged 20 or less they account for almost 60% of such masses. There are four separate types of fibroadenoma: common fibroadenoma, giant fibroadenoma, juvenile fibroadenoma, and phyllodes tumours. There is no universally accepted definition of what constitutes a giant fibroadenoma, but most consider that it should measure over 5 cm in diameter. Juvenile fibroadenomas occur in adolescent girls and sometimes undergo rapid growth but are managed in the same way as the common fibroadenoma. Phyllodes tumours are distinct pathological entities and cannot always be clinically differentiated from fibroadenomas.
A definitive diagnosis of fibroadenoma can be made by a combination of clinical examination, ultrasonography, and fine needle aspiration cytology. They have characteristic mammographic features in older patients when they calcify, and a few patients have multiple fibroadenomas. Current evidence of the natural history of fibroadenomas suggests that less than 5% of them increase in size and about one quarter get smaller or completely disappear.
Management - Fibroadenomas over 4 cm in diameter should be excised. In women aged under 40 fibroadenomas diagnosed by clinical examination, ultrasonography, and fine needle aspiration cytology do not need excision unless this is requested by the patient. In women aged over 40 a selective policy of excision should be used to ensure that breast cancers are not missed.
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