The rarest type of breast cancer often goes unnoticed

A phyllodes tumor is a rare breast tumor that develops in the connective tissue of the breast, rather than in the milk ducts as is the case with most breast cancers. The name phyllodes comes from Greek and means "leaf-like," a reference to the typical appearance of the tumor under the microscope. Phyllodes tumors account for less than 1% of all breast tumors. They can be benign or malignant, and sometimes fall somewhere in between. It is precisely this unpredictability that makes this condition complex.

Benign, borderline, or malignant

Doctors divide phyllodes tumors into three categories: benign (does not spread, but may return after removal), borderline (has characteristics of both benign and malignant), and malignant (can grow rapidly, but rarely spreads). Approximately 10–20% of phyllodes tumors are malignant.

Phyllodes tumors are most common in women between the ages of 35 and 55. However, they can also affect younger women and, in rare cases, men. There is no known cause, and they do not appear to be related to hormonal factors such as pregnancy or contraception. The most noticeable symptom is a fast-growing, painless lump, usually firm and clearly palpable. As the lump grows larger, it can cause tension or redness of the skin. Because this tumor often resembles a benign connective tissue tumor, it is initially underestimated. The lump becomes visible with a mammogram or ultrasound, but at least a biopsy is needed for a correct diagnosis. Sometimes the doubt remains and only the laboratory examination of the lump after surgery provides a definitive answer. This can be very confusing. What was initially considered harmless sometimes turns out to be malignant after all.

A phyllodes tumor must always be completely removed, with a wide margin. This means that in some cases a mastectomy is necessary. Chemotherapy and hormone therapy are not used. Radiation therapy is sometimes used if the tumor keeps coming back. That is why people who have had a phyllodes tumor must be monitored continuously with regular check-ups. The prognosis is usually good, even for malignant forms.