Nodular Fasciitis of the Buccal Mucosa with a Novel USP6 Gene Rearrangement: A Case Report and Review of the Literature

Mallissa Vuong, Haider A. Mejbel, Alexander C. Mackinnon, Dylan Roden, David I. Suster

Research output: Contribution to journalArticlepeer-review

Abstract

Nodular fasciitis is a rare but benign fibroblastic proliferation that typically presents as a solitary lesion with rapid growth and variable mitotic activity. The lesions usually occur on the extremities and occasionally in the head/neck region. Involvement of the buccal mucosa is extremely rare with only few reports in the literature; in this case report, we describe a 41 year old female who presented with a 6-month history of a stable intraoral lump at the junction of the upper and lower lip. Fine needle aspiration revealed an atypical spindle cell population with plump cells. The surgical excision demonstrated a well circumscribed tan-white firm nodule. Histologic examination revealed a spindle cell proliferation that grew in short, intersecting fascicles with focal storiform architecture. The lesion had a pushing border that was not overtly infiltrative and the stroma contained focal myxoid changes giving a “tissue culture” appearance to the cells. Immunohistochemical testing showed the tumor cells were vimentin (+), SMA (+), weakly Calponin (+), and desmin (-), cytokeratin (-), AE1/AE3 (-), S100 (-), ALK (-), STAT6 (-), and beta-catenin (-). Fluorescence in-situ hybridization (FISH) revealed a USP6 gene rearrangement with an atypical probe pattern. Next generation sequencing identified a novel SPTAN1::USP6 fusion gene confirming the diagnosis of buccal nodular fasciitis. Identification of the characteristic histologic features and USP6 gene rearrangements helped support the diagnosis. A review of the literature identified 25 cases of nodular fasciitis involving the buccal mucosa. The occurrence of this tumor in an unusual location may pose difficulties for diagnosis.

Original languageEnglish
Article number79
JournalHead and Neck Pathology
Volume18
Issue number1
DOIs
StatePublished - Dec 2024
Externally publishedYes

Keywords

  • Myofibroblastic
  • Next generation sequencing
  • Nodular fasciitis
  • Oral cavity
  • USP6

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