title: Rare case of biphasic tumor of the breast with prominent CD34-positive spindle cells.
abstract: We report an unusual case of biphasic tumor of the breast with prominent CD34-positive spindle cells. A 53-year-old woman presented with a mass in her right breast. Following an incisional biopsy, a partial mastectomy was done. Histologically, the tumor was a biphasic variant of a malignant spindle cell tumor of the breast. The lack of a leaf-like structure, together with the apparent myoid features of the spindle-shaped tumor cells, made it difficult to distinguish from malignant phyllodes tumor and from myoepithelial carcinoma. Immunohistochemistry revealed the spindle-shaped tumor cells to be myofibroblastic, but not myoepithelial in nature, ultimately categorizing this tumor as a malignant phyllodes tumor with prominent myofibroblastic differentiation.
authors.affiliation: Department of Pathology, Yamagata University School of Medicine, Yamagata, Japan. mahayasi@med.id.yamagata-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
authors.forename: G
authors.initials: G
authors.lastname: Tamura
authors.forename: O
authors.initials: O
authors.lastname: Matsumoto
authors.forename: T
authors.initials: T
authors.lastname: Motoyama
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis*; D001940:Breast / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015412:Mastectomy, Segmental; D008854:Microscopy, Electron; D008875:Middle Aged; D003557:Phyllodes Tumor / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
chemical_list: D018952:Antigens, CD34