Synchronous collision tumor of malignant phyllodes and invasive ductal carcinoma

Phyllodes tumor (PT) constitutes <1% of breast tumors. Malignancy usually arises from the stromal component forming homologous or heterologous elements such as chondrosarcoma, liposarcoma, fibrosarcoma, osteosarcoma, or rhabdomyosarcoma. Rarely, carcinoma can arise from the epithelial cells within the PT. Rarer is the occurrence of collision tumor of malignant phyllodes and carcinoma in the breast which lacks the exact incidence since only few cases are reported in the literature. This is another such rare case of synchronous collision tumor of malignant phyllodes having chondrosarcomatous and osteosarcomatous differentiation associated with invasive and in situ ductal carcinoma having metastatic carcinomatous deposits in axillary lymph nodes in a 43-year-old female. Hence, extensive sampling of the gross specimen is crucial in diagnosing the collision tumors which are not detected either in breast imaging studies or during the surgery. Since malignant PT usually spreads through a hematogenous route, it has to be treated by wide local excision or simple mastectomy without the axillary lymph node dissection. If a PT is associated with carcinoma, the patient management and prognosis depend on the stage of the carcinoma.