Phyllodes Tumour
DEFINITION
"Phyllodes" - from Greek Phyllon = 'leaf'.
A cousin of the fibroadenoma; nonepithelial.
AKA cystosarcoma phyllodes (old term, see below).
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EPIDEMIOLOGY

Incidence
Most common neoplasm of nonepithelial origin of the breast.
Relatively rare.
- estimated at between 2-4% as common as fibroadenomas.
Estimated at 2.1 / million for malignant Phyllodes.

Age
Any age
Median is 45yrs (R&A)
- ie 20 years later than average fibroadenoma patient.
- and same age as cancer group.
- very few are younger than 25 years, but can occur in adolescents.
--> in women over 35 with a rapidly enlarging ?fibroadenoma, consider phyllodes.

Gender
Are exclusive to the female breast.

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AETIOLOGY

Tumour
Spectrum from benign to malignant.
Non-epithelial stromal tumours - see below.
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BIOLOGICAL BEHAVIOUR

Pathophysiology
Phylloides arises from periductal stromal tissue, fibroadenomas do not.

Pathology
Gross pathology
A bulky tumour.
- usually sharply demarcated.
- round, freely mobile, smooth contour, firm.
- median size 4-5cm at excision; can be any size, perhaps very large.

Histopathology
When cut, gives an embossed 'leaflike' appearance.
First named 'cystosarcoma phyllodes' (1838 by Müller).
- on microscopy, cystlike spaces lined with low epithelium are often seen.
- however sarcoma is an exaggeration, as most are believed benign.
The term 'fibroadenoma phyllodes' is again only acceptable to some of the spectrum
- so the simple term phyllodes tumour is preferred (WHO recommendation).

How does it differ from a fibroadenoma?
Two key features (R&A):
i) stromal hypercellularity.
- can be difficult to distinguish from hypercellular fibroadenomas (if possible, if not its academic anyway usually).
ii) presence of benign glandular elements integral in the neoplasm.
It is the amount and appearance of the stromal elements that determine whether it be called a fibroadenoma or phylloides.
- and what its chances of malignacy are.

A description of malignant potential is given based on stromal characteristics (Sabiston).
- 25% = malignant
- 60% = benign
- 15% = indeterminate potential.

Risk factors of metastatic potential? (Sabiston)
Histological features include nuclear atypia, numerous mitoses and loss of relationship between glands and stroma (stromal overgrowth).
- the latter may be the most useful (Petrek).
Multivariate retrospective analysis of histology:
- histologic type (one study)
- stromal type + presence of necrosis (one study)
- NOT to tumour size or margin status.

Natural history

Local recurrence
For benign lesions enucleated, 5-year LR of 4% reported (Sabiston).
- "20% of all phyllodes will recur if excised without margin" (Petrek).
Multiple reports describe "malignant transformation".
- ie recurrent tumour more aggressive histologically than the primary.
- however this is uncommon in reality (Petrek).

Metastasis
The cytologically malignant tumours have metastatic potential.
- varies from 3-12% in various series (R&A),
- overall <5% metastasise, 20% of malignant lesions and up to 5% of benign lesions (Sabiston).
- axillary mets are rare
Rather, most spreading systemically do so haematogenously (Sabiston).
- commonly to lung, bone, possibly to CNS (R&A), possibly abdo viscera, mediastinum (Sabiston).
- contain only the stromal elements histologically.
- no reports of long-term survivors --> truly sarcomas.
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MANIFESTATIONS

Symptoms
Almost always a rounded, painless, smooth, multinodular breast mass.
- most report continuous growth
- others rapid growth in a previously stable longstanding nodule.

Signs
Overlying skin almost never attached.
- but may be shiny and stretched.
- rarely ulcerates, when due to ischaemia however, rather than invasion.
Nipple will not be retracted or invaded.

Axillary lymphadenopathy
May be detected in up to 20%, but as above is rarely due to mets.
- rather suspect necrotic or infected tumour mass.

Diagnosis
Impossible to distinguish clinically, radiologically, or even via triple assessment from a fibroadenoma.
Consider this diagnosis if:
- larger size
- history of rapid growth
- patients >35
But not exclusive to these groups.
The diagnosis is usually made from excision biopsy.

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INVESTIGATIONS

Pathology
Cytology is inaccurate comparing low-grade phyllodes from fibroadenoma.
One series of core biopsy showed true +ve rate of 50% (Sabiston).

Imaging
Mammogram
Round densities, smooth borders.
Usually indistinguishable from fibroadenoma.
- irregular margins may suggest local invasion.

Ultrasound
Discrete structure with cystic spaces.
Again, often mistaken for fibroadenoma.

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MANAGEMENT

Operative
Excision to 1cm negative margins is advocated (where phylloides is known) to lower LR risk (Sabiston).
- LR is usually seen within a few years of surgery.
- inversely correlated with width of negative resection margin.
- do not simply enucleate the lesion --> unacceptable LR rate (see above)
Routine mastectomy and axillary clearance can be avoided (see above).
- however removal of low nodes, especially if palpable cannot be criticized.

What if I thought it was a fibroadenoma at the time, and simply enucleated it?
Most patients should undergo reexcision within 4 weeks.

What if the histology returns a tumour with strong malignant potential?
Breast preservation has been accomplished with satisfactory outcomes.

Local Recurrence
Usually treated with total mastectomy.
However, can still be cured by adequate WLE (R&A).
- take 2-3cm margins.
- more aggressive Rx to confront possibility of malignant transformation is ill-advised as this is rare (see above).

Sentinal node?
No, tend not to spread via LNs

Palliative Treatments for Metastatic Disease
Optimal therapy not defined (Sabiston).
- no sustained remission from any treatment.
- good published data is lacking.
Most used = cyclophosphamide- or doxyrubacin- containing combos.
- ie as for sarcomas, not breast cancers.
Several used cisplatin and etoposide combination chemo.
Radiation to symptomatic mets may help.
Most contain estrogen and progesterone receptors
- palliation with hormone manipulation has not been extensively explored.
Distant pulmonary single mets may be excised with possibility of cure.

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REFERENCES
Sabiston 17th.
Rosai & Ackerman 9th.
Petrek JE.  Phyllodes Tumour.  Chapter in Diseases of the Breast.