Giant benign phyllodes tumor with lactating changes in pregnancy: a case report

Phyllodes tumor in pregnancy is extremely rare. We present the first case ever reported of a giant benign phyllodes tumor with lactating changes during pregnancy.

A 36-year-old female patient at the 32nd week of pregnancy presented with a huge mass in left breast for 5-6 months. Physical examination revealed a firm palpable 20 cm mass occupying the whole left breast. Ultrasound guided core needle biopsy demonstrated a fibroepithelial lesion suggestive of benign phyllodes tumor. She was scheduled for mastectomy three weeks after birth delivery. The microscopic examination of the resected specimen revealed the mass consisted mainly of lactating components with areas of hypercellular stroma and epithelial proliferation in leaf-like pattern. Finally, the pathological report confirmed a giant benign phyllodes tumor with lactating changes and frees all surgical margins.

Phyllodes tumor in pregnancy is rare with just nine cases reported. It is unknown if the rapidly growing mass in pregnant patient is hormone-dependent. This is the first report of a giant benign phyllodes tumor with lactating changes in pregnant patient. In these large phyllodes tumors, heterogeneous stromal components are common. It is occasionally difficult to distinguish between benign phyllodes tumor with lactating changes and lactating adenoma. Because the surgical treatment and local recurrence rate are different between these two diseases, we need to clearly differentiate benign phyllodes tumors from other benign breast diseases.

This case emphasizes the heterogeneity of giant phyllodes tumors. Therefore, it is important to thoroughly examine the resected specimen for possible additional components. The key point is that adequate and clear surgical margins in any phyllodes tumors must be achieved to reduce local recurrence.