Malignant phyllodes tumour with a noninvasive ductal carcinoma component

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• Phyllodes tumors are rare biphasic neoplasms of the breast, typically benign but can exhibit malignant potential.
• Malignant transformation can occur in either the stromal or epithelial component, or both.
• Coexistence of phyllodes tumor with ductal carcinoma is exceptionally rare, posing diagnostic and therapeutic challenges.

Observation:

• An 80-year-old Japanese woman presented with a large, ulcerated breast tumor detected during routine examination.
• Macroscopic examination suggested a phyllodes tumor; histological analysis revealed a malignant phyllodes tumor with a noninvasive ductal carcinoma component.
• The epithelial component showed progression to intraductal papillary carcinoma, while the stromal component exhibited fibrosarcoma, osteosarcoma, and rhabdomyosarcoma.

Findings:

• The tumor demonstrated malignant changes in both stromal and epithelial elements, with independent histological origins.
• No stromal invasion by the carcinoma or direct transition between stromal and epithelial elements was observed.
• The patient experienced rapid disease progression with widespread pulmonary and subcutaneous metastases post-mastectomy.

Implications:

• This case highlights the aggressive behavior of malignant phyllodes tumors with carcinomatous components.
• The independent nature of the stromal and epithelial malignant components suggests phyllodes tumors may be a precursor to carcinosarcoma.
• Further research is needed to understand the pathogenesis and optimize treatment strategies for these rare breast malignancies.