Malignant phyllodes tumor of the breast with axillary lymph node metastasis: case report and review of the literature

Excerpt

Phyllodes tumors are fibroepithelial tumors with characteristic histological features. The epithelial component is always benign with luminal and myoepithelial cells, and is surrounded by a cellular mesenchymal component. Phyllodes tumors typically show an exaggerated intracanalicular growth pattern, which results in leaf-like structures projecting into cysts [1]. Since not all phyllodes tumors are cystic, the original name “cystosarcoma phylloides” given by the first describer Johannes Müller (1838) was misleading and later changed by the WHO (1981) to “phyllodes tumor” [2, 3]. According to the current WHO classification, phyllodes tumors are classified as benign, borderline, or malignant based on stromal atypia, stromal cellularity, mitotic rate, stromal overgrowth, and tumor margins [4]. The mesenchymal component determines the biological behavior of the phyllodes tumor. At one end of the spectrum are benign phyllodes tumors with a stroma slightly more cellular than in fibroadenoma and lacking a significant degree of atypia and mitosis, on the other end there are malignant phyllodes tumors with highly atypical and polymorphic stroma with brisk mitotic activity and infiltrative growth into the adjacent tissues. Malignant phyllodes tumors often show an overgrowth by the malignant mesenchymal component, which may lead to a reduction of the epithelial component including the leaf-like pattern and the appearance of a spindle cell neoplasm. …