Myofibroblastoma of the breast with diverse differentiations

Arch Pathol Lab Med. 1997 Jun;121(6):599-603.


Background: The histogenesis of myofibroblastoma of the breast remains unknown.

Design: Two cases of myofibroblastoma of the female breast were analyzed using light microscopy and immunohistochemistry.

Results: The tumors were well circumscribed and predominantly composed of bland bipolar spindle cells and interspersed bands of hyalinized collagen. Additionally, one tumor contained a cartilaginous island, and the other contained a well-defined small nodule that consisted of fascicular arrangements of mitotically inactive atypical cells, simulating atypical leiomyoma. Both lesions contained a fatty element. Immunohistochemically, spindle tumor cells expressed desmin, alpha-smooth muscle actin, muscle actin, and CD34. The atypical cells were strongly and diffusely positive for all these markers. Both tumors were DNA diploid and had a moderate S-phase fraction. The patients have no evidence of disease 4 and 18 months after simple excision.

Conclusions: Myofibroblastoma of the breast may be a benign mesenchymal neoplasm capable of diverse lines of differentiation.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Antigens, CD34 / analysis
  • Biomarkers, Tumor / analysis
  • Breast Neoplasms / genetics
  • Breast Neoplasms / pathology*
  • Breast Neoplasms / surgery
  • Cell Nucleus / pathology
  • Cell Transformation, Neoplastic
  • Cytoplasm / pathology
  • DNA, Neoplasm / analysis
  • Desmin / analysis
  • Diploidy
  • Female
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Neoplasms, Muscle Tissue / genetics
  • Neoplasms, Muscle Tissue / pathology*
  • Neoplasms, Muscle Tissue / surgery
  • S Phase
  • S100 Proteins / analysis


  • Antigens, CD34
  • Biomarkers, Tumor
  • DNA, Neoplasm
  • Desmin
  • S100 Proteins