DICER1 mutation-positive giant botryoid fibroepithelial polyp of the urinary bladder mimicking embryonal rhabdomyosarcoma

Hum Pathol. 2019 Feb:84:1-7. doi: 10.1016/j.humpath.2018.05.015. Epub 2018 Jun 5.

Abstract

Fibroepithelial polyps of the urinary tract are rare lesions. They occur mainly in the upper urinary tract of children. A high disease prevalence has been reported in families with pleuropulmonary blastoma. Here we present a case of a 46-year-old woman who presented with a giant botryoid fibroepithelial polyp of the urinary bladder. Histologically, the lesion showed prominent botryoid features with an embryonal rhabdomyosarcoma-like cambium layer lacking nuclear or cellular atypia. Immunohistochemical analysis ruled out rhabdomyoblastic differentiation. Next-generation sequencing was performed on the polyp tissue and revealed two pathogenic mutations in the DICER1 ribonuclease III (DICER1) gene (c.[5439G>T]; p.[Glu1813Asp] and c.[1525C>T]; p.[Arg509*]). Truncating DICER1 mutations, accompanied by characteristic "hotspot" mutations affecting the RNase IIIB domain of DICER1 are typically seen in DICER1-related lesions. Our findings indicate a role of DICER1 mutations in the pathogenesis of fibroepithelial polyps of the urinary tract.

Keywords: DICER1; DICER1 syndrome; Embryonal rhabdomyosarcoma; Fibroepithelial polyps; Pleuropulmonary blastoma.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • DEAD-box RNA Helicases / genetics*
  • Diagnosis, Differential
  • Female
  • Humans
  • Middle Aged
  • Mutation
  • Polyps / diagnosis
  • Polyps / genetics*
  • Polyps / pathology*
  • Rhabdomyosarcoma, Embryonal / diagnosis
  • Ribonuclease III / genetics*
  • Urinary Bladder Diseases / diagnosis
  • Urinary Bladder Diseases / genetics*
  • Urinary Bladder Diseases / pathology*

Substances

  • DICER1 protein, human
  • Ribonuclease III
  • DEAD-box RNA Helicases