Encyclopedia of Pathology

Living Edition
| Editors: J.H.J.M. van Krieken

Pseudosarcomatous Myofibroblastic Proliferations

Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-28845-1_5459-1



A benign lesion of myofibroblasts showing overlap with nodular fasciitis, inflammatory myofibroblastic tumor, and granulation tissue.

Clinical Features

  • Incidence


  • Age

    Mainly seen in adults.

  • Sex

    No gender predilection.

  • Site

    The mucosal surface of the genitourinary tract is mostly affected, but the lesions can occur at any mucosal site of the gastrointestinal tract and head and neck area (Proppe et al. 1984; Harik et al. 2006).

  • Treatment

    Surgical excision usually is curative.

  • Outcome

    These lesions are benign but can occasionally recur.


The lesion usually presents as polypoid, exophytic, and ulcerated masses.


Plump, elongated myofibroblasts are arranged in loose fascicles (Fig. 1). Some cells have prominent eccentric cytoplasm and mimic rhabdomyoblasts (Fig. 2). The nuclei are...
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  1. Harik, L. R., Merino, C., Coindre, J. M., Amin, M. B., Pedeutour, F., & Weiss, S. W. (2006). Pseudosarcomatous myofibroblastic proliferations of the bladder: A clinicopathologic study of 42 cases. The American Journal of Surgical Pathology, 30, 787–794.CrossRefGoogle Scholar
  2. Jebastin, J. A. S., Smith, S. C., Perry, K. D., Gupta, N. S., Alanee, S., Carskadon, S., Chitale, D. A., Palanisamy, N., & Williamson, S. R. (2018). Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract are genetically different from nodular fasciitis and lack USP6, ROS1 and ETV6 gene rearrangements. Histopathology, 73, 321–326.CrossRefGoogle Scholar
  3. Marino-Enriquez, A., & Hornick, J. L. (2019). Pseudosarcomatous myofibroblastic proliferation. In J. L. Hornick (Ed.), Practical soft tissue pathology (pp. 25–27). Philadelphia: Elsevier.Google Scholar
  4. Proppe, K. H., Scully, R. E., & Rosai, J. (1984). Postoperative spindle cell nodules of genitourinary tract resembling sarcomas. A report of eight cases. The American Journal of Surgical Pathology, 8, 101–108.CrossRefGoogle Scholar

Authors and Affiliations

  1. 1.Department of Imaging and Pathology, Translational Cell and Tissue ResearchKU Leuven, University of LeuvenLeuvenBelgium