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Phyllodes Tumor (Cystosarcoma Phyllodes)

  • Author: Donald R Lannin, MD; Chief Editor: John Geibel, MD, DSc, MSc, MA  more...
Updated: Jun 20, 2016


Cystosarcoma phyllodes (from Greek kystis ["sac, bladder"], sarcoma ["fleshy tumor"] and phyllon ["leaf"]) is a rare, predominantly benign tumor that occurs almost exclusively in the female breast.[1, 2] Grossly, the tumor displays characteristics of a large, malignant sarcoma, takes on a leaflike appearance when sectioned, and displays epithelial, cystlike spaces when viewed histologically. Because most of these tumors are benign, the term cystosarcoma is potentially misleading. Accordingly, the term currently favored is phyllodes tumor.


Pathophysiology and Etiology

Phyllodes tumor is the most commonly occurring nonepithelial neoplasm of the breast, though it represents only about 1% of tumors in the breast.[3]  It has a smooth, sharply demarcated texture and typically is freely movable. It is a relatively large tumor, with an average size of 5 cm (though lesions larger than 30 cm have been reported). The etiology of phyllodes tumors is unknown.

Because of limited data, the relative percentages of benign and malignant phyllodes tumors are not well defined. Reports have suggested, however, that about 85-90% of phyllodes tumors are benign and that approximately 10-15% are malignant.[4]

Although benign phyllodes tumors do not metastasize, they have a tendency to grow aggressively and can recur locally.[3]  Like other sarcomas, malignant phyllodes tumors metastasize hematogenously. Unfortunately, the pathologic appearance of a phyllodes tumor does not always predict the neoplasm's clinical behavior; in some cases, therefore, there is a degree of uncertainty about the lesion's classification.

The characteristics of a malignant phyllodes tumor include the following[5] :

  • Recurrent malignant tumors seem to be more aggressive than the original tumor
  • The lungs are the most common metastatic site, followed by the skeleton, heart, and liver
  • Symptoms of metastatic involvement can arise from as early as a few months to as late as 12 years after the initial therapy
  • Most patients with metastases die within 3 years of the initial treatment [6]
  • No cures for systemic metastases exist
  • Roughly 30% of patients with malignant phyllodes tumors die of the disease

Although most phyllodes tumors are benign, it is nonetheless important not to underestimate the potential of these lesions for malignancy. Moreover, some juvenile fibroadenomas in teenagers can look like phyllodes tumors on histologic examination; however, they behave in a benign fashion similar to that of other fibroadenomas. The difficulty of distinguishing among fibroadenomas, benign phyllodes tumors, and malignant phyllodes tumors may be vexing for even the most experienced pathologist.[7]



Phyllodes tumors occur almost exclusively in females, though rare cases have been reported in males. The tumors can develop in people of any age; however, the median age is the fifth decade of life.



If a phyllodes tumor is benign, the long-term prognosis is excellent after adequate local excision. However, the possibility for local recurrence after excision always exists, particularly with lesions that display malignant histology.[8, 9, 10]  If the tumor recurs locally after excision, further local excision or total mastectomy is typically curative. Metastatic disease is typically observed in the lung, mediastinum, and skeleton.[5]


Patient Education

As for all breast neoplasms, self-examination remains the most important initial detection mechanism for phyllodes tumors. Appropriate teaching of this procedure is vital for early detection of all breast neoplasms.

For patient education information, see the Women's Health Center and the Cancer Center, as well as Breast Cancer and Breast Self-Exam.

Contributor Information and Disclosures

Donald R Lannin, MD Professor, Department of Surgery, Section of Oncology, Director Emeritus, Yale-New Haven Breast Center

Donald R Lannin, MD is a member of the following medical societies: Alpha Omega Alpha, American Cancer Society, American College of Surgeons

Disclosure: Nothing to disclose.


Anastasios K Konstantakos, MD Clinical Associate Surgeon, Department of Cardiovascular Surgery, Billings Clinic

Disclosure: Nothing to disclose.

John H Raaf, MD, PhD (Retired) Professor, Department of Surgery, Case Western Reserve University School of Medicine

John H Raaf, MD, PhD is a member of the following medical societies: American Association for Cancer Research, American College of Surgeons, Central Surgical Association, Society of Surgical Oncology, American Association of Endocrine Surgeons, American Society of Clinical Oncology

Disclosure: Nothing to disclose.

Chief Editor

John Geibel, MD, DSc, MSc, MA Vice Chair and Professor, Department of Surgery, Section of Gastrointestinal Medicine, and Department of Cellular and Molecular Physiology, Yale University School of Medicine; Director, Surgical Research, Department of Surgery, Yale-New Haven Hospital; American Gastroenterological Association Fellow

John Geibel, MD, DSc, MSc, MA is a member of the following medical societies: American Gastroenterological Association, American Physiological Society, American Society of Nephrology, Association for Academic Surgery, International Society of Nephrology, New York Academy of Sciences, Society for Surgery of the Alimentary Tract

Disclosure: Received royalty from AMGEN for consulting; Received ownership interest from Ardelyx for consulting.


Brian James Daley, MD, MBA, FACS Associate Program Director, Professor, Department of Surgery, Division of Trauma and Critical Care, University of Tennessee School of Medicine

Brian James Daley, MD, MBA, FACS is a member of the following medical societies: American Association for the Surgery of Trauma, American College of Chest Physicians, American College of Surgeons, American Medical Association, Association for Academic Surgery, Association for Surgical Education, Eastern Association for the Surgery of Trauma, Shock Society, Society of Critical Care Medicine, Southeastern Surgical Congress, andTennessee Medical Association

Disclosure: Nothing to disclose.

Michael A Grosso, MD Consulting Staff, Department of Cardiothoracic Surgery, St Francis Hospital

Michael A Grosso, MD is a member of the following medical societies: American College of Surgeons, Society of Thoracic Surgeons, and Society of University Surgeons

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Reference Salary Employment

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