Malignant phyllodes tumor with osteosarcomatous differentiation metastasizing to small bowel and causing intestinal obstruction

Phyllodes tumors are relatively uncommon breast neoplasms constituting 0.3-1.0% of all breast tumors according to the 2012 World Health Organization book. Up to 10-20% of all phyllodes tumors are malignant and thus potentially capable of hematogenous metastatic spread particularly to the lungs and bones. Metastasis to the gastrointestinal tract, however, is unusual and might lead to diagnostic confusion particularly in the absence of relevant background clinical information. Phyllodes with osteosarcomatous and chondrosarcomatous heterologous differentiation may be particularly prone to metastasis. We report an unusual case of metastatic phyllodes tumor to small bowel that demonstrated extensive osteosarcomatous and chondrosarcomatous stromal elements.