Fibroma-like PEComa: a newly recognized soft tissue neoplasm in tuberous sclerosis patients—imaging features and review of literature

Gitanjali Bajaj, Matthew R. Lindberg, Winson Chee, Debopam Samanta, Avneesh Chhabra

Research output: Contribution to journalArticlepeer-review

Abstract

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of spindled to epithelioid cells that co-express both melanocytic and myogenic markers. Recently, in 2018, a distinctive variant of PEComa has been described that arises in association with tuberous sclerosis complex (TSC) and resembles a fibroma by conventional morphology (called fibroma-like PEComa). Herein, we describe a case of a fibroma-like PEComa in a 4-year-old male child with a known diagnosis of tuberous sclerosis who presented with a firm mass along the anteromedial aspect of the right knee. The mass was excised, and microscopic examination showed bland spindled to stellate cells embedded in a dense collagenous stroma, morphologically resembling a fibroma. Immunohistochemistry analysis showed positivity for desmin (a myogenic marker) and HMB45 (a melanocytic marker), a hallmark for PEComas. To our knowledge, only six cases of fibroma-like PEComa have been described in the literature so far and this is the first report of such a tumor in the medial retinaculum of the knee joint with illustrations of conventional and diffusion imaging features. This case highlights the unique association of fibroma-like PEComa lesions with TSC. This should be considered a differential diagnosis for T2 hypointense masses in tuberous sclerosis patients. In addition, a diagnosis of fibroma-like PEComa should prompt further evaluation for associated TSC.

Original languageEnglish (US)
Pages (from-to)881-887
Number of pages7
JournalSkeletal radiology
Volume51
Issue number4
DOIs
StatePublished - Apr 2022

Keywords

  • Diffusion-weighted imaging (DWI)
  • Fibroma
  • Fibroma-like PEComa
  • Magnetic resonance imaging (MRI)
  • Perivascular epithelioid cell tumor (PEComa)
  • Tenosynovial giant cell tumor (TSGCT)
  • Tuberous sclerosis complex (TSC)

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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