Breast-nonmalignant - Phyllodes Tumor

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Breast-nonmalignant

Benign tumors / changes

Phyllodes Tumor - general

Reviewer: Hind Nassar, M.D. in January 2009 (see Authors page)

Revised: 24 October 2012, last major update April 2010

Definition

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● Biphasic tumor resembling fibroadenoma, but with hypercellular mesenchymal component organized in leaf-like pattern around benign epithelial / myoepithelial lined spaces

Terminology

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● Also called cystosarcoma phyllodes (coined by Johannes Muller but not a good term since usually benign)

● Also spelled phylloides

● Means “leaf” in Greek

Epidemiology

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● 1% of breast tumors

● Average age 45 years (age 25-30 years in Asians, Aust N Z J Surg 1988;58:301)

● Rare in children or men (gynecomastia is more likely)

● More common in Hispanics, particularly if born in Latin America (Cancer 1993;71:3020)

Etiology

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● A fibroepithelial tumor, like fibroadenoma; that arises from intralobular stroma

● Rosai considers it a stromal tumor with the capacity to induce glandular formation

Clinical features

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● Tumors in young girls/women have similar morphology and behavior as older women (Am J Surg Pathol 1998;22:64)

● Either discrete palpable mass that rapidly enlarges or non-palpable mass identified on screening mammogram

● Axillary nodal enlargement is present in 17%, but usually reactive and not due to metastatic disease

● Rarely secretes insulin-like growth factor II causing hypoglycemia (Breast J 2007;13:189)

Prognostic factors

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● Traditional histological classification as benign, borderline or malignant; this classification has strong prognostic value (Eur J Obstet Gynecol Reprod Biol 2008;138:217)

● AFIP Fascicle, 4th series, recommends use of low grade / high grade terminology, because of difficulty in predicting behavior based solely on histology

● Positive margin status is significantly associated with recurrence (Archives 2006;130:1516)

● Overall good prognosis (Jpn J Clin Oncol 2007;37:730) with only rare deaths due to disease (Ann Surg Oncol 2007;14:2961)

Case reports

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● 30 year old woman (Case of Week #255)

Treatment

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● Wide local excision with a rim of uninvolved breast tissue

● Axillary nodal dissection is not necessary

Gross description (Macroscopy)

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● Well circumscribed, firm, bulging mass; often received as a shelled-out specimen

● Cut surface is tan-pink-gray

● Large lesions have whorled pattern with curved clefts resembling leaf buds

● Variable hemorrhage or necrosis in large lesions

Micro description (Histopathology)

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● Must take sufficient sections (at least one per cm of diameter), and classify based on area of highest cellular activity and most florid architectural pattern

● Important histologic features for classification as benign, borderline or malignant:

● (1) character of tumor-normal interface,

● (2) proportion of neoplastic stroma to epithelial structures,

● (3) mitotic figures/10 high power fields

● (4) anaplastic cytology

● Should report presence of tumor at margin, a major determinant of local recurrence

Cytology description

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● Epithelial cell clusters, naked nuclei, atypical cells, myxoid changes

● Background of mitotic active stromal cells

● Fibromyxoid stromal fragments with spindled nuclei, fibroblastic pavements (Cancer Cytopathol 2010;118:33)

Positive stains

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● Stroma: vimentin, actin

Negative stains

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● Stroma: keratin (CAM 5.2, CK7, AE1-AE3), EMA, S100

Electron microscopy descriptions

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● Features of fibroblasts - myofibroblasts

Differential Diagnosis

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● Fibroadenoma: no tissue fragmentation, no increased stromal cellularity around glands, no stromal overgrowth, no increased mitotic figures (Int J Surg Pathol 2008;16:137)

Additional references

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● eMedicine, Stanford University

End of Breast-nonmalignant > Benign tumors / changes > Phyllodes tumor - general

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