Breast Care A-Z · Condition · PHYLLODES

Phyllodes tumour

also: phyllodes tumor, cystosarcoma phyllodes, phylloides tumour · pronounced fy-LOH-deez

A phyllodes tumour is an uncommon breast tumour that grows in the connective tissue; most are benign, but because they can grow quickly and recur, they are removed with a clear margin. You have probably been told a lump first thought to be a fibroadenoma is actually a phyllodes tumour, and are wondering what that means.

Quick answers

Is a phyllodes tumour cancer?

Most are not. Around 60–70% are benign, around 15–20% are borderline, and around 10–20% are malignant. Even malignant phyllodes tumours behave differently from conventional breast cancer — they spread through the bloodstream rather than the lymph nodes — and they are managed with surgery as the main treatment, sometimes followed by radiotherapy.

Will the lump come back after surgery?

Local recurrence rates depend on the type and the surgical margin. Benign phyllodes excised with a clear margin has a recurrence rate of under 10%. Borderline and malignant tumours have higher recurrence rates and need wider surgery. After excision, follow-up imaging is arranged to detect any recurrence early.

Why is my phyllodes tumour being treated differently from a fibroadenoma?

Because phyllodes tumours behave differently from fibroadenomas — they tend to grow more rapidly, they can recur locally if not fully removed, and they need a clear surgical margin to be managed safely. Fibroadenomas can usually be left alone or removed with a smaller operation if symptomatic.

Phyllodes Tumour -- Breastory Encyclopaedia Plate LXXIV Plate covering phyllodes tumour (cystosarcoma phyllodes): histology, classification, comparison with fibroadenoma, management, and surveillance. ONCOLOGY · RARE BREAST TUMOURS PLATE LXXIV phyllodes tumour cystosarcoma phyllodes · fibroepithelial tumour a rare fibroepithelial breast tumour classified as benign, borderline, or malignant, characterised by rapid growth and requiring wide local excision FIG 01 -- Histological cross-section: phyllodes tumour architecture Outer breast tissue (normal stroma + ducts) stromal hypercellularity Leaf architecture: fibrous stroma core covered by epithelium (biphasic). Stromal overgrowth = malignant behaviour. Inset: FA vs PT FA: small, compact PT: large, leaf-like i -- leaf-like (phyllodes) architecture ii -- hypercellular stroma (key feature) iii -- stromal overgrowth (malignant phyllodes) iv -- epithelial component (benign gland lining) v -- well-circumscribed pseudo-capsule Classification (WHO) Benign: mild atypia, <5 mitoses/10HPF, no overgrowth Borderline: moderate atypia, 5-9 mitoses/10HPF Malignant: marked atypia, >10 mitoses, stromal overgrowth, heterologous elements Heterologous: liposarcoma, osteosarcoma elements Why wide excision? Benign phyllodes: 20% local recurrence if margins <1cm Borderline: 25% recurrence rate Malignant: 30% recurrence + metastatic potential Spread: haematogenous (lung, bone) -- not lymph nodes FIG 02 -- Benign vs Malignant phyllodes: comparison Feature Benign Malignant Stromal cellularity Mild Marked Mitoses <5/10HPF >10/10HPF Atypia Mild Severe Stromal overgrowth Absent Present Margin needed ≥1cm (borderline/malignant); no tumour on ink (benign) ≥1cm clear (borderline/malignant) Recurrence ~20% if margins inadequate ~30% Metastasis Absent ~25% (lung, bone) Lymph node spread Not applicable Rare 5-yr survival ~99% ~60-80% Management WLE: no tumour on ink (benign); ≥1cm (borderline/malignant) WLE + ≥1cm margins + adjuvant discussion FIG 03 -- Phyllodes vs Fibroadenoma: differential features Feature Phyllodes Fibroadenoma Age 40-50 peak 15-35 peak Size Often >3cm, rapid growth Usually <3cm Growth Rapid (months) Slow Stroma Hypercellular Moderate cellularity Architecture Leaf-like (phyllodes) Intracanalicular or pericanalicular Margins Pushing but pseudo-capsule Well-defined Epithelium Compressed by stroma Regular Malignant potential Yes (10-25%) <1% Treatment WLE with clear margins Conservative / watch FIG 04 -- Clinical pathway: phyllodes tumour management 1 Rapidly growing lump presentation 2 Triple assessment (clinical + USS + core biopsy 3 Excision biopsy for definitive diagnosis 4 Histology classification (benign/borderline/malignant) 5 Re-excision to 1cm margins if initially shelled out 6 Surveillance (annual USS x3 years) FIG 05 -- Related conditions and procedures Benign phyllodes (B3 biopsy) Borderline phyllodes Malignant phyllodes WLE (grade-appropriate margins) Re-excision for close margins Malignant phyllodes chest wall recurrence FIG 06 -- Key statistics ~1% of breast tumours [1] 20% local recurrence with inadequate margins [2] Malignant phyllodes -- ~25% metastasis rate [3] Lymph node spread is rare -- haematogenous spread instead [4] References 1. Tan PH et al. WHO classification phyllodes. Histopathology 2012 2. Barth RJ et al. Phyllodes margins and recurrence. Cancer 1999 3. Macdonald OK et al. Malignant phyllodes survival. Cancer 2006 4. NICE NG101. Early breast cancer 2023 5. WHO Classification of Tumours: Breast 5th ed. IARC 2022 Clinically authored by Dr Fiona Tsang-Wright , FRCS (Gen Surg) GMC 4549831 · ORCID 0000-0003-4801-026X
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Definition
A phyllodes tumour is an uncommon fibroepithelial breast lesion that resembles a fibroadenoma on imaging but behaves differently — it tends to grow more rapidly, it can recur locally if not fully removed, and surgical excision is recommended even when the tumour is benign.

Common questions The questions patients ask first

Is a phyllodes tumour cancer?
Most are not. Around 60–70% are benign, around 15–20% are borderline, and around 10–20% are malignant1. Even malignant phyllodes tumours behave differently from conventional breast cancer — they spread through the bloodstream rather than the lymph nodes — and they are managed with surgery as the main treatment, sometimes followed by radiotherapy.
Will the lump come back after surgery?
Local recurrence rates depend on the type and the surgical margin. Benign phyllodes excised with a clear margin has a recurrence rate of under 10%1. Borderline and malignant tumours have higher recurrence rates and need wider surgery. After excision, follow-up imaging is arranged to detect any recurrence early.
Why is my phyllodes tumour being treated differently from a fibroadenoma?
Because phyllodes tumours behave differently from fibroadenomas — they tend to grow more rapidly, they can recur locally if not fully removed, and they need a clear surgical margin to be managed safely. Fibroadenomas can usually be left alone or removed with a smaller operation if symptomatic.
Will I need chemotherapy or radiotherapy?
Most patients with benign phyllodes tumours need surgery alone — no chemotherapy or radiotherapy. Borderline phyllodes are sometimes followed with radiotherapy if margins are close. Malignant phyllodes may have radiotherapy and, very rarely, chemotherapy, depending on the individual case. The plan is decided at the multidisciplinary team meeting.

A phyllodes tumour is an uncommon fibroepithelial breast lesion that resembles a fibroadenoma on imaging but behaves differently — it tends to grow more rapidly, it can recur locally if not fully removed, and surgical excision is recommended even when the tumour is benign.

Phyllodes tumours are rare — fewer than 1% of breast tumours1. Most are benign, but unlike fibroadenomas they need to be surgically removed to prevent local regrowth. A small minority are borderline or malignant, and these need wider surgical clearance and sometimes additional follow-up.

Orientation Why you might be reading about this

You have probably been told that a lump initially thought to be a fibroadenoma is actually a phyllodes tumour, and you are wondering what that means. The unfamiliar name and the word “tumour” are often the most worrying part — most phyllodes tumours are benign, but they are genuinely a different entity from fibroadenoma and the management is more involved. This page explains what a phyllodes tumour is, how it is diagnosed, and what the standard treatment looks like.

Related terms: Fibroadenoma · Breast lump · Core biopsy · Breast ultrasound · Triple assessment

Definition What a phyllodes tumour is

The name phyllodes comes from the Greek for “leaf-like”, describing the characteristic leaf-like pattern the tumour shows under the microscope. Like a fibroadenoma, a phyllodes tumour is a fibroepithelial lesion — it contains both glandular and stromal (connective tissue) components. The difference is in the stroma: in a phyllodes tumour, the stromal cells are more crowded, more cellular, and divide more actively than in a fibroadenoma.

Pathologists divide phyllodes tumours into three categories based on their microscopic features:

  • Benign phyllodes — the most common; behaves predictably with appropriate surgery.
  • Borderline phyllodes — intermediate features; higher chance of local recurrence; needs wider surgical margins.
  • Malignant phyllodes — rare (around 10–15% of phyllodes); can occasionally spread1 (typically through the bloodstream rather than lymph nodes); needs wider surgery and is sometimes followed by adjuvant treatment.

The vast majority of phyllodes tumours encountered in private breast practice are benign. The terminology — particularly the older name cystosarcoma phyllodes — sounds more aggressive than most of these tumours behave.

Diagnosis How a phyllodes tumour is diagnosed

The diagnosis often starts with a presumed fibroadenoma:

  • Clinical presentation — usually a smooth, firm, mobile lump, sometimes growing more rapidly than expected for a fibroadenoma. Phyllodes tumours typically present in women in their 40s and 50s — slightly older than the typical fibroadenoma age group.
  • Breast ultrasound — typically shows a well-defined oval mass that can be hard to distinguish from a fibroadenoma. Some features (cystic spaces within the lesion, larger size) raise suspicion of phyllodes but cannot reliably distinguish them.
  • Mammogram — usually shows a smooth oval density.
  • Core biopsy — the key test. Many phyllodes tumours are diagnosed when a presumed fibroadenoma is biopsied, particularly if it is large or growing.

Notably, a needle biopsy alone cannot always make a confident distinction between a fibroadenoma and a benign phyllodes tumour — they share many microscopic features and the leaf-like pattern is sometimes only obvious on the whole excised specimen. This is one reason larger or growing fibroadenoma-like lumps are usually removed surgically, rather than monitored.

Treatment How a phyllodes tumour is treated

The standard treatment is surgical excision with a clear margin. The aim is to remove the tumour together with a rim of healthy tissue around it, to reduce the chance of local recurrence.

  • Benign phyllodes — usually excised with a margin of around 1 cm. Recurrence rate after wide excision is low1 (less than 10%).
  • Borderline and malignant phyllodes — excised with a wider margin, often around 2 cm1. Mastectomy is occasionally needed for very large tumours, or where adequate margins cannot be achieved with breast-conserving surgery.

Biopsy-confirmed borderline and malignant phyllodes tumours are reviewed jointly with the breast and sarcoma multidisciplinary teams in line with ABS 2025 guidance, with expert pathology review where needed.

Sentinel lymph node biopsy is not routinely performed for phyllodes tumours, even malignant ones, because they spread through the bloodstream rather than via the lymph nodes. This is one of the differences between phyllodes and conventional breast cancer.

For most patients with a benign phyllodes tumour, the operation is similar in scale to a fibroadenoma excision but with a slightly wider margin. Recovery is similarly quick.

At consultation What to discuss with your surgeon

If a phyllodes tumour has been diagnosed on biopsy:

  • Whether the biopsy result is “benign”, “borderline”, or “malignant” — this changes the surgical plan.
  • The size of the planned margin and what that means for cosmetic outcome.
  • The plan for follow-up — most benign phyllodes need a single follow-up after surgery; borderline and malignant tumours need more structured ongoing surveillance.
  • Whether the multidisciplinary team has reviewed the case (they should have).

If the diagnosis or the planned excision is unclear, a second-opinion consultation is a normal next step. Wide excision is planned with the same surgical team — see breast cancer surgery.

Resources Further reading

Sources & guidance

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  1. review Chiba A, Hoskin TL, Hieken TJ, Boughey JC. Phyllodes Tumor of the Breast: A Review. Annals of Surgical Oncology. 2017 ;24(11):3366-3374 doi:10.1245/s10434-017-6022-0 Cited for: Phyllodes tumour subtype distribution (benign/borderline/malignant), management and recurrence rates.