Phyllodes tumour

Phyllodes tumour, also known as cystosarcoma phyllodes, is a rare fibroepithelial tumour of the breast which has some resemblance to a fibroadenoma. It is typically a large, fast growing mass that forms from the periductal stroma of the breast.

Phyllodes tumours account for less than 0.3-1% of all breast neoplasms. It is predominantly a tumour of adult women, with very few examples reported in adolescents. The occurrence is most common between the ages of 40 and 60, before the menopause (peak incidence ~45 years). This is about 15 years older than the typical age of patients with fibroadenoma.

Patients typically present with a painless, rapid growing breast mass for which imaging is requested. 

Its original term cystosarcoma phyllodes was coined in view of its leaflike pattern of growth. A phyllodes tumour may be considered benign, borderline, or malignant depending on histologic features including stromal cellularity, infiltration at the tumour edge, and mitotic activity. At histologic analysis, the tumour can resemble a giant fibroadenoma with both epithelial and stromal components being seen.

Fine needle aspiration is inaccurate, and even core biopsy has moderate sensitivity due to tumour heterogeneity causing inadequate sampling.

The tumours can be quite large at presentation.

Typically seen as non-specific large rounded oval or lobulated, generally well circumscribed, lesions with smooth margins. A radiolucent halo may be present. Calcification (typically coarse and plaque like) may be seen in a very small proportion. 

General sonographic features are non-specific and can mimic that of a fibroadenoma 7.

On ultrasound, an inhomogeneous, solid-appearing mass is the most common manifestation. A solid mass containing single or multiple, round or cleft like cystic spaces and demonstrating posterior acoustic enhancement strongly suggests the diagnosis of phyllodes tumour. Vascularisation is usually present in the solid components.

In practice, most lesions are indistinguishable from fibroadenomas on both mammography and ultrasound. This is why interval enlargement of a "fibroadenoma" is seen as an indication for a needle biopsy. Large lesions (i.e. >4 cm) may qualify for excision out of hand because needle biopsy may not be representative of the pathology in the whole lesion.

As with mammography, they are typically seen as oval, round, or lobulated masses with circumscribed margins. Signal characteristics can vary with histological grade 11 but in general are:

  • T1: usually of low signal 8
  • T2: can be variable ranging from homogenous low 8 to high 4-5 signal
  • T1 C+ (Gd): the solid components enhance after contrast administration
  • dynamic contrast: the kinetic curve pattern can be gradual slow or have rapid enhancement

Inhomogeneous signal may rarely result in the context of accompanying haemorrhage or cystic spaces 9. Some suggest inhomogeneous signal as indicative of benignity 10.

It is a locally invasive tumour. Treatment is usually with surgical excision. Large tumours may even require a full mastectomy. Both benign and malignant phyllodes tumours have a tendency to recur if not widely excised. Malignant degeneration is seen in 5-25% 4 (malignant phyllodes tumour).

After wide local excision there is relatively frequent local recurrence (up to 25%) and up to 10% can metastasise. The mode of metastases in such cases is by haematogenous route. 

The name is derived from the Greek word: "phullon" meaning "leaf"Phyllodes tumours were first described in 1838 by Johannes Muller as "cystosarcoma phyllodes".

For ultrasound and MRI appearances consider 6,8:

Breast imaging and pathology
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Article information

rID: 1872
System: Breast
Synonyms or Alternate Spellings:
  • Phyllodes
  • Cystosarcoma phyllodes
  • Cystosarcoma phylloides
  • Phyllodes tumor
  • Phyllodes tumours
  • Phyllodes tumors

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