Large Fibroadenoma and Phyllodes Tumour Excision

Fibroadenomas and phyllodes tumours are both fibroepithelial lesions — benign breast lumps that arise from the glandular and connective tissue of the breast. While they share some features on imaging and clinical examination, they are distinct conditions with different natural histories and different management requirements.

Fibroadenomas

Fibroadenomas are the most common benign breast lump in women under 40, though they can occur at any age. They are smooth, firm, well-defined, and mobile — sometimes described as feeling like a "breast mouse" because of the way they move freely under the fingers during examination. They are not cancerous and do not significantly increase the risk of breast cancer in most cases.

Most fibroadenomas are small (under 3 cm), stable, and can be safely monitored with periodic ultrasound without any surgical intervention. Reassurance and surveillance is the standard approach for a confirmed, small, stable fibroadenoma in a young woman.

However, surgical excision is recommended in the following situations.

The fibroadenoma is large, generally greater than 3 to 4 cm, where the ongoing presence of a significant breast mass warrants removal. The lump is growing on serial ultrasound surveillance, particularly if it is growing rapidly. The fibroadenoma is causing discomfort or distortion of the breast contour. The core biopsy result is borderline or shows atypical features that cannot be fully characterised without complete excision. The patient prefers removal for personal reasons, including ongoing anxiety about the lump's presence.

A giant fibroadenoma is defined as a fibroadenoma greater than 5 cm in diameter. These are uncommon and occur most frequently in adolescent girls and young women. They can grow rapidly and cause significant breast distortion. Surgical excision is almost always recommended for giant fibroadenomas.

Phyllodes Tumours

Phyllodes tumours are less common than fibroadenomas but are an important and distinct clinical entity. They can appear very similar to a fibroadenoma on clinical examination and ultrasound, presenting as a smooth, well-defined breast mass, but they have a different biological behaviour that requires a different management approach.

Phyllodes tumours are classified as benign, borderline, or malignant based on their microscopic features. The majority (approximately 60 to 75%) are benign, but even benign phyllodes tumours have a meaningful tendency to recur locally if not excised with an adequate margin of surrounding normal tissue. Borderline and malignant phyllodes tumours carry a higher risk of local recurrence and, in the case of malignant phyllodes, a risk of distant spread.

Unlike simple fibroadenomas, phyllodes tumours cannot be safely monitored without excision once diagnosed. Surgical excision with a clear margin of at least 1 cm of surrounding normal breast tissue is the recommended treatment for all phyllodes tumours regardless of their classification.

Several features on clinical examination or imaging may raise suspicion for a phyllodes tumour rather than a simple fibroadenoma, including rapid recent growth, a large size (particularly greater than 3 cm), an age at presentation over 35 to 40 years, and certain features on core biopsy pathology. However, the diagnosis is frequently not confirmed until after surgical excision and full pathological analysis of the specimen.

Diagnosis

Both fibroadenomas and phyllodes tumours are assessed with the same triple assessment approach used for all breast lumps: clinical examination, imaging (ultrasound and mammogram where appropriate), and core biopsy. Core biopsy is the most informative diagnostic tool and can often distinguish between a fibroadenoma and a phyllodes tumour, though the distinction is not always possible on biopsy alone and may only be fully established after excision.

Where there is any diagnostic uncertainty — particularly in a rapidly growing lump or one with features atypical for a simple fibroadenoma — surgical excision and complete pathological analysis is the recommended approach.

Surgical Excision

Excision of a fibroadenoma or phyllodes tumour is performed under general anaesthetic as a day procedure in most cases. The approach varies depending on the size and location of the lesion and whether margin clearance is required.

For fibroadenomas, the goal is complete removal of the lump through the smallest incision that achieves this safely. Incisions are placed in inconspicuous positions — within natural skin creases, at the areola border, or along the breast fold — to minimise visible scarring. The surrounding breast tissue is closed to restore a smooth contour, and wounds are closed with buried dissolving sutures. In younger women and for smaller fibroadenomas, vacuum-assisted excision (a minimally invasive technique using a large-bore vacuum biopsy probe under ultrasound guidance) is an option for complete removal without a formal open incision, and is discussed where appropriate.

For phyllodes tumours, adequate margin excision is the primary surgical goal. The surgeon removes the tumour with a rim of normal breast tissue on all sides — a wider excision than for a simple fibroadenoma. The margin requirement means the incision and tissue removal are somewhat larger, and oncoplastic reshaping techniques may be used where needed to restore breast contour after a more generous excision. All tissue is sent for full pathological analysis to confirm the classification of the phyllodes tumour and the adequacy of margins.

If margins are inadequate after initial excision of a phyllodes tumour, re-excision to achieve a clear margin is recommended to reduce the risk of local recurrence.

Recovery

Recovery from fibroadenoma and phyllodes tumour excision is straightforward for the majority of patients. Most patients go home the same day. Some bruising and tenderness at the wound site is expected for one to two weeks. Wounds are closed with dissolving sutures under a waterproof dressing that can be left in place until the first post-operative appointment. Most patients can return to desk work within a few days and to strenuous exercise within three to four weeks.

Pathology results are typically available within five to seven days of surgery and are reviewed at the post-operative appointment. For phyllodes tumours, the pathology report confirms the classification and margin status and guides any recommendation for further management or surveillance.

Follow-Up

For excised fibroadenomas with a straightforward histological result, long-term follow-up beyond the post-operative wound check is not routinely required, though ongoing breast awareness and screening is encouraged.

For phyllodes tumours, clinical and imaging surveillance after excision is recommended, as local recurrence is possible even after apparently adequate excision. The frequency and duration of surveillance depends on the classification (benign, borderline, or malignant) and will be outlined by your surgeon after the final pathology is available. Local recurrence of a phyllodes tumour should be excised promptly.

Booking an Appointment

If you have been told you have a fibroadenoma or a lump that may be a phyllodes tumour and would like specialist assessment, or if you have been referred for surgical excision, we welcome the opportunity to see you.

This page is intended as a general guide only and does not replace personalised medical advice. The most appropriate management for any breast lump should be discussed with your specialist.