Benign breast lumps

Benign breast lumps are common. Accurate diagnosis and effective treatment of women with benign breast lumps is crucial to relieve their anxiety and/or morbidity. Fibroadenomas and breast cysts account for most benign breast lumps. What follows is practical advice to understand and manage these two common benign conditions.

Dr Jose Cid Fernandez, Oncoplastic Breast Surgeon, Perth
Fibroadenomas

A fibroadenoma is not a tumour but is considered an aberration of normal breast development that contains a mixture of epithelial and stromal tissue. Clinically fibroadenomas present as discrete, mobile, rubbery lumps in young women, or as an incidental finding on breast imaging of older women. 

The majority do not change in size over time, some can become smaller or disappear, and a small proportion get larger, especially during pregnancy and breast feeding. Rapid growth is uncommon but can occur in adolescents (juvenile fibroadenoma) and in older women with other lumps that can resemble fibroadenomas, such as phyllodes (leaf-like) tumours.

A breast ultrasound can usually differentiate a fibroadenoma from a malignant breast lump. The diagnosis is confirmed with an ultrasound-guided biopsy, either by fine needle aspiration or preferably core biopsy. For the very young (i.e., under 18) with very small fibroadenomas shown unequivocally on ultrasound, biopsy can be omitted and a follow-up ultrasound at six months is recommended. 

For older women, breast lumps are investigated by way of triple assessment, which consists of a clinical breast examination, breast imaging (ultrasound, plus bilateral mammography in the over 35) and a breast biopsy – a benign triple assessment result is reassuring, and follow-up ultrasounds can be useful to monitor size change over time. Occasionally triple assessment results are unclear, for example, benign biopsy but worrisome breast ultrasound or mammogram appearance. In this scenario women are advised to have their breast lump surgically excised and examined. 

Preoperative markings of left breast fibroadenoma and skin incision in the inframammary fold (left), and postoperative hidden scar (right).

Management depends on the patient’s age, preference, lump size, and biopsy results. Surgical excision can be offered to those who wish to have their lump removed. However, women with histologically proven fibroadenomas less than 3cm in diameter can be reassured of the benign diagnosis. 

Surgical excision is recommended in patients with:

  • Lumps greater than 3cm, or those which cause distortion of the breast contour
  • Lumps undergoing rapid growth
  • Biopsy unable to distinguish fibroadenoma from phyllodes tumour

Excision for pain is not guaranteed to improve this symptom. Surgery is performed under general anaesthetic through a cosmetically placed skin incision, usually at the base of the breast or at the edge of the areola – an inframammary approach with tunnelling through the retro-glandular space provides access to most breast lumps and leaves an inconspicuous scar. Alternatively, small fibroadenomas can be removed with a vacuum-assisted core biopsy needle under local anaesthetic.

Breast cysts

Breast cysts are fluid-filled distended breast lobules, regarded as an aberration of normal breast involution. Cysts are affected by hormonal changes, thus occurring commonly in pre-menopausal women, and often disappear after the menopause, although they have become more common in older women taking HRT. Clinically they present as discrete breast lumps, often multiple, and some women have cysts bilaterally. Smaller cysts may cause no symptoms and be found incidentally on breast ultrasound or mammogram.

Breast ultrasound is essential to differentiate cystic and solid lesions, and can also distinguish between simple and complex cysts, the latter characterised by internal echoic filling defects, or thickened wall, and absent posterior acoustic enhancement. As for fibroadenomas, women over 35 have also a bilateral mammography.

Simple asymptomatic cysts can be left alone, and patients can be reassured that they are not cancerous, nor do they increase the risk of cancer. Large or painful cysts require aspiration, usually with a fine needle under ultrasound guidance. The fluid obtained is commonly clear or straw coloured. 

Cysts aspirated to dryness and without other demonstrated pathology do not require follow up, although repeat investigation and aspiration can be performed if/when the cyst recurs. If the fluid yielded is blood stained, it is sent for cytology. If a residual lump is palpable after aspiration this necessitates further imaging and biopsy. Complex cysts are aspirated too, with fluid cytology as necessary also. Core biopsy of thickened wall or cystic wall projections is performed to exclude an intra-cystic papilloma or carcinoma. 

It is important to counsel women known to have breast cysts not to assume that a new breast lump is just another cyst, but to seek medical advice for any new breast lump.

Key messages
  • Fibroadenomas and breast cysts are now not regarded as disease but aberrations of normal breast development and involution respectively
  • Most fibroadenomas do not require surgical excision, unless large or with equivocal biopsy findings
  • Breast cysts require aspiration only if symptomatic or complex on ultrasound.

Author competing interests – nil