A case of phyllodes tumor with rapid growth during pregnancy and lactation period: a case report

TL;DR

A 39-year-old woman developed a rapidly growing phyllodes tumor during pregnancy and lactation, which was later diagnosed as benign.

Contribution

This case highlights the rare occurrence of phyllodes tumor growth during pregnancy and lactation.

Findings

The tumor increased in size during pregnancy and lactation, reaching 85 mm in diameter.

The tumor contained a milk-like substance, which may have contributed to its rapid growth.

Histological analysis confirmed a benign phyllodes tumor with degeneration.

Abstract

The age of onset of the phyllodes tumor is generally in the late 40 s, and diagnosis and treatment during pregnancy and lactation are rare. We herein present a case of a phyllodes tumor that rapidly increased in size during the pregnancy and lactation period.

A 39-year-old woman was referred to our hospital with a mass in the right breast that increased in size during the pregnancy and lactation period. On ultrasound (5 week postpartum), a well-defined lobulated mass with internal septations and fluid retention was observed. Magnetic resonance imaging of the breast at 8 week postpartum revealed a 70-mm-sized smooth-margin mass with multilocular cystic components. Marked proliferation of stromal cells with high cell density was observed in a biopsy specimen taken at the previous hospital. We diagnosed the mass as a phyllodes tumor of borderline malignancy and excised it at 13 week postpartum. The excised tumor was 85 mm in diameter and its interior was filled with a milk-like substance. Histologically, there was only a mild increase in stromal cell density but fibrosis with associated degeneration was prominent. The final diagnosis was benign phyllodes tumor with degeneration.

We report a case of a phyllodes tumor that rapidly increased in size during pregnancy and the lactation period. The accumulation of a milk-like substance was thought to be responsible for the rapid growth of the tumor.

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