Breast nonmalignant
Reactive spindle cell nodule

Topic Completed: 1 April 2010

Minor changes: 4 September 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Reactive spindle cell nodule

Hind Warzecha, M.D.
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Cite this page: Warzecha H. Reactive spindle cell nodule. website. Accessed May 31st, 2020.
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

AFIP images


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)
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