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Reactive Spindle Cell Nodules of the Breast After Core Biopsy or Fine-Needle Aspiration

Helenice Gobbi MD, PhD, Gary Tse MD, David L. Page MD, Sandra J. Olson MS, Roy A. Jensen MD, Jean F. Simpson MD
DOI: http://dx.doi.org/10.1309/RPW4-CXCC-1JHM-0TL7 288-294 First published online: 1 February 2000


Reactive spindle cell nodules (RSCNs) arising postoperatively or after fine-needle aspiration (FNA) have been reported previously in the genitourinary tract and thyroid. We describe 18 cases of similar lesions in breast, associated with a history of core needle biopsy or FNA. The majority of the RSCNs (15 cases) were associated with papillary lesions or complex sclerosing lesions. The RSCNs were nonencapsulated and relatively nodular, measuring 1.5 to 9 mm. They were composed of spindle cells with mild to moderate nuclear pleomorphism and a low mitotic count. A network of small blood vessels, macrophages, and lymphocytes was present in all cases. Immunohistochemically, the spindle cells expressed smooth and specific muscle actins, supporting a myofibroblastic origin. The association of RSCNs with needle trauma to fibrosclerotic lesions, such as complex sclerosing lesions and papillary lesions that regularly have myofibroblasts, suggests an exuberant reparative cause. Recognition of this reactive process will avoid overdiagnosis of mammary spindle cell malignant neoplasm.

Key Words:
  • Spindle cell nodules
  • Breast fine-needle aspiration
  • Post-core needle biopsy changes
  • Complex sclerosing lesion
  • Papilloma
  • Inflammatory pseudotumor