A phyllodes tumor often grows rapidly and occasionally contains microcysts;
however, the tumor rarely shows a morphologically intracystic pattern. We
experienced a rare case of a phyllodes tumor with a solid mass growing into
the cyst. A 62-year-old female noticed a tumor in her right breast in Janu
ary 1995, The tumor grew rapidly and she visited our out-patient clinic in
February 1995, On physical examination, a 10 x 8 cm, well defined and movab
le mass with a smooth surface was palpated in the upper outer quadrant of t
he right breast. Mammography showed a large tumor shadow in the upper outer
quadrant of the right breast without any microcalcification. Ultrasonograp
hy revealed a large cystic shadow with a low echoic lesion and solid compon
ent with heterogeneous internal echo in the cyst. Under general anesthesia,
the tu mor was widely excised. The resected specimen was 11.5 x 11 x 11 cm
in size and the tumor was not invasive to surrounding tissues. Old bloody
fluid was contained within the cyst. The gross appearance showed papillary
process protrusions into a central cystic cavity. Histological examination
revealed a borderline case of phyllodes tumor. Two years after the operatio
n, she is doing well without any recurrence.