Breast - nonmalignant
Inflammatory / infectious
Reactive spindle cell nodule

Author: Hind Nassar, M.D. (see Authors page)

Revised: 27 July 2017, last major update April 2010

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Reactive spindle cell nodule

Cite this page: Reactive spindle cell nodule. website. Accessed July 17th, 2018.
Definition / general
  • Benign spindle cell tumor, rare complication of breast core biopsy or fine needle aspiration (Am J Clin Pathol 1991;96:76)
  • Similar to counterparts in bladder, prostate or other GU sites but few publications in breast
  • May be due to exuberant reparative process
Clinical features
Case reports
Gross description
  • Up to 1 cm, nodular, not encapsulated
Microscopic (histologic) description
  • Myofibroblastic spindle cells with mild / moderate nuclear pleomorphism, small vessel proliferation, foam cells, lymphocytes, hemosiderin
Microscopic (histologic) images

Images hosted on Pathout server:


AFIP fig 2-70: interlacing fascicles of myofibroblasts

Uniform cells are mixed with inflammatory cells

Images hosted on other servers:


Left: muscularis propria,
Right: spindle cell nodule

Positive stains
Differential diagnosis
  • Fibromatosis: spindle cells form interlacing fascicles with variable collagen deposition and cellularity; usually extends into surrounding fat and glandular parenchyma
  • Inflammatory myofibroblastic tumor: prominent inflammatory infiltrate, not postoperative
  • Leiomyosarcoma: no recent history of biopsy or surgery; often marked atypia and necrosis
  • Low grade sarcoma
  • Low grade spindle cell carcinoma
  • Myofibroblastoma: uniform, bland spindle cells haphazardly arranged in fascicles with pushing borders, separated by broad bands of hyalinized collagen
  • Nodular fasciitis: superficial, well circumscribed, zonation effect with hypocellular central region and hypercellular periphery; feathery, tissue culture-like growth pattern due to abundant ground substance; often with mucoid pools (microcysts)