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Phyllodes Tumour of the Breast: Symptoms, Diagnosis, Surgery & Follow-Up

  • Prof. Dr. Zahid Mahmood
  • August 14, 2026

Phyllodes Tumour of the Breast: Symptoms, Diagnosis, Surgery & Follow-Up

Medically reviewed by Prof. Dr. Zahid Mahmood, MBBS, FCPS — General, Laparoscopic & Laser Surgeon, Lahore.

A phyllodes tumour is a rare growth that develops in the supporting tissue of the breast. It often appears as a firm, painless breast lump and may grow quickly. Phyllodes tumours can resemble fibroadenomas on examination and imaging, but they require different treatment.

Most phyllodes tumours are benign. Others are classified as borderline or malignant. A rapidly enlarging breast lump should therefore be assessed promptly rather than assumed to be a harmless fibroadenoma.

What is a phyllodes tumour?

Phyllodes tumours are fibroepithelial tumours containing both breast ducts and specialised stromal tissue. The word “phyllodes” means leaf-like, describing their appearance under the microscope. The older term cystosarcoma phyllodes is now rarely used.

They account for only a small proportion of breast tumours and most commonly occur in women in their 40s and 50s, although they can develop at other ages.

Are all phyllodes tumours cancerous?

No. After examining the complete surgical specimen, the pathologist classifies the tumour as:

  • Benign: the most common type, with the lowest risk of recurrence or spread.
  • Borderline: has features between benign and malignant disease and needs closer follow-up.
  • Malignant: behaves like a soft-tissue sarcoma and can spread through the bloodstream, most often to the lungs and sometimes to bone.

This classification is based on stromal cellularity and atypia, mitotic activity, stromal overgrowth and whether the tumour border is pushing or infiltrative.

Symptoms and warning signs

The usual symptom is a breast lump. Features that should raise suspicion include:

  • A firm, mobile, painless breast lump
  • A lump that increases noticeably in size over weeks or months
  • A previously diagnosed fibroadenoma that starts growing
  • A large or lobulated breast mass
  • Stretching, redness or visible veins over the skin of a very large lump
  • Rarely, skin ulceration caused by pressure from a massive tumour

These features do not prove that a lump is malignant, but they require proper breast assessment.

Phyllodes tumour versus fibroadenoma

Both conditions can produce a smooth, well-defined and mobile lump. Fibroadenomas are common, especially in younger women, while phyllodes tumours are rare and tend to occur later in life. Rapid growth, larger size and a lobulated appearance increase suspicion for phyllodes, but no symptom or scan can reliably distinguish every case.

How is it diagnosed?

A breast lump should undergo triple assessment:

  1. Clinical assessment: history and examination of both breasts and lymph-node areas.
  2. Imaging: ultrasound, with mammography according to age and clinical circumstances.
  3. Tissue diagnosis: ultrasound-guided core needle biopsy.

Ultrasound may show a well-defined, oval or lobulated solid mass, sometimes with clefts or small cystic spaces. Mammography may show a dense, rounded or lobulated mass. MRI is not routinely more accurate than ultrasound and mammography for diagnosing phyllodes tumours.

Why can core biopsy be inconclusive?

Phyllodes tumours can be heterogeneous, and a core needle collects only small samples. A cellular fibroadenoma and a phyllodes tumour may look similar in those samples. The report may therefore say “cellular fibroepithelial lesion” or “phyllodes tumour cannot be excluded.”

When the lump is enlarging or clinical, imaging and biopsy findings do not agree, diagnostic surgical excision may be needed. Fine-needle aspiration alone is not reliable for distinguishing these lesions.

Treatment: surgery is the main treatment

Surgery aims to remove the tumour completely with an appropriate rim of normal tissue. The operation depends on tumour size, breast size, location, biopsy findings and whether the tumour is benign, borderline or malignant.

Breast-conserving surgery

Most phyllodes tumours can be treated by local excision while preserving the breast, provided an adequate clear margin can be achieved. Current specialist guidance recommends a subtype-specific approach rather than the same margin for every tumour:

  • Benign: aim for complete excision with the capsule intact. If the tumour reaches the edge, the benefits and risks of further surgery are discussed individually.
  • Borderline: a wider clear margin is preferred, with re-excision considered according to the measured margin and pathological features.
  • Malignant: a wider clear margin is usually required; further surgery may be recommended if the margin is inadequate.

The exact margin decision should be made after review of the final pathology in a breast multidisciplinary meeting.

When is mastectomy required?

Mastectomy may be advised when the tumour is very large relative to the breast, clear margins cannot be obtained with breast conservation, or disease is recurrent or malignant. Mastectomy does not automatically mean that the tumour has spread. Breast reconstruction can be discussed when appropriate.

Are lymph nodes removed?

Routine sentinel lymph-node biopsy or axillary clearance is generally not required. Unlike common breast carcinomas, malignant phyllodes tumours usually spread through the bloodstream rather than the lymphatic system. Enlarged lymph nodes are often reactive, but a suspicious node should be assessed and biopsied.

Are radiotherapy or chemotherapy needed?

  • Benign: radiotherapy and chemotherapy are not routinely used.
  • Borderline: radiotherapy is not needed in most cases but may be considered when risk is high and further surgery is not possible.
  • Malignant: radiotherapy may be considered for a large tumour, multifocal or recurrent disease, or an inadequate margin that cannot be improved surgically.

Routine chemotherapy after complete removal has no clearly established benefit. Metastatic malignant phyllodes tumour is managed with a specialist sarcoma team, sometimes using sarcoma chemotherapy or treatment directed at limited metastatic sites.

Can a phyllodes tumour return?

Local recurrence can occur in every subtype, particularly after incomplete excision. Most recurrences develop during the first few years. A new lump near the surgical scar or elsewhere in the breast should be examined promptly.

Follow-up after surgery

Follow-up is based on the final subtype and operation:

  • Benign tumours may use patient-initiated follow-up after appropriate counselling.
  • Borderline tumours need planned clinical and breast-imaging surveillance.
  • Malignant tumours require closer clinical and breast-imaging follow-up, plus chest imaging because the lungs are the commonest site of distant spread.

Your treating team will provide an individual schedule. Continue normal breast awareness and report any new or rapidly growing lump, persistent cough, unexplained breathlessness or bone pain.

Frequently asked questions

Does a benign phyllodes tumour turn into cancer?

Most benign tumours remain benign. Rare recurrence may have a higher grade, which is why complete pathology review and awareness of new lumps are important.

Can phyllodes tumour affect both breasts?

It usually affects one breast. A new lump in either breast should still undergo standard assessment.

Can it be treated without surgery?

Surgery is the standard treatment because imaging and core biopsy may not classify the entire tumour reliably, and incomplete removal increases the risk of local recurrence.

Will surgery remove the whole breast?

Not necessarily. Breast-conserving excision is possible when the tumour can be removed with an appropriate margin and an acceptable cosmetic result.

Key message

A phyllodes tumour is a rare breast tumour that often resembles a fibroadenoma but may grow rapidly. Most are benign, while some are borderline or malignant. Triple assessment and core biopsy are essential, although complete classification may require surgical excision. Surgery with an appropriate clear margin is the main treatment, and follow-up depends on the final subtype.

Breast lump assessment in Lahore

Prof. Dr. Zahid Mahmood assesses enlarging breast lumps, arranges triple assessment and plans breast-conserving surgery or referral to specialist breast and sarcoma teams when required.

For an appointment, call 0300 413 0159 or visit professorzahid.com.

This article provides general education and does not replace personal medical assessment. Any new or rapidly enlarging breast lump requires prompt clinical review.

Medical references

  1. Williams NS, O’Connell PR, McCaskie AW, editors. Bailey & Love’s Short Practice of Surgery. 28th ed. CRC Press; 2023. Chapter 58, “The breast,” pp. 922–923.
  2. Mills C, et al. Contemporary management of phyllodes tumours of the breast: recommendations from the UK Association of Breast Surgery. British Journal of Surgery. 2025.
  3. National Cancer Institute. Definition of phyllodes tumour.

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