A case of giant cell-rich solitary fibrous tumor in the external auditory canal

Sayaka Yuzawa, Satoshi Tanikawa, Isamu Kunibe, Hiroshi Nishihara, Kazuo Nagashima, Shinya Tanaka

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2 Citations (Scopus)

Abstract

We present a rare case of giant cell-rich solitary fibrous tumor (SFT) arising at the left external auditory canal in a 31-year-old woman. The tumor was well-circumscribed and composed of spindle-shaped cells with abundant collagenous bands. Scattered multinucleate giant cells were observed, some of which lined pseudovascular spaces. Although a focal mild-hypercellular area was observed, mitoses were rare and necrosis was absent. Interstitial mast cells were scattered, especially in the hypercellular area. Immunohistochemically, CD34, vimentin, and Bcl-2 presented diffuse positivity. Moreover, both mononuclear spindle cells and multinucleate cells showed nuclear STAT6 positivity, while NAB2-STAT6 fusion gene could not be detected by reverse transcription polymerase chain reaction using formalin-fixed specimen. These findings suggest the pathological diagnosis of giant cell-rich SFT, previously known as giant cell angiofibroma, which is a rare variant of SFT with multinucleate giant cells and occurs predominantly in orbital region. Although giant cell-rich SFTs of extra-orbital sites have been reported, to our knowledge, this is the first case arising in the external auditory canal. Giant cell-rich SFT should be considered as a differential diagnosis of spindle cell lesion with multinucleate giant cells, and STAT6 immunohistochemistry should be performed to distinguish this rare tumor from other mesenchymal neoplasms.

Original languageEnglish
Pages (from-to)701-705
Number of pages5
JournalPathology international
Volume66
Issue number12
DOIs
Publication statusPublished - 2016 Dec 1
Externally publishedYes

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Keywords

  • external auditory canal
  • giant cell angiofibroma
  • NAB2
  • solitary fibrous tumor
  • STAT6

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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