Summary
We describe a patient with a malignant phyllodes tumor with both lobular carcinoma in situ and liposarcomatous stromal differentiation. Although lobular carcinoma in situ and adipose differentiation have been reported as separate features rarely seen in the phyllodes tumor, we are unaware of any cases in which both of these features have been seen within the same tumor. The prognosis for this patient related not only to the malignant stromal component of the tumor but also to her increased risk of developing carcinoma in the remaining breast tissue.