Subcutaneous chondromyxoid fibroma with a novel PNISR::GRM1 fusion—report of a primary soft tissue tumour without connection to an underlying bone

Zupan, Andrej (author), Salapura, Vladka (author), Šekoranja, Daja (author), Pižem, Jože (author)

Chondromyxoid fibroma (CMF) is a rare benign bone tumour. While CMF located entirely on the surface of a bone (i.e. juxtacortical CMF) has been well characterised, CMF has not so far been convincingly documented to arise in soft tissues without connection to an underlying bone. We report a subcutaneous CMF in a 34-year-old male, located on the distal medial aspect of the right thigh without any connection with the femur. The tumour measured 15 mm, it was well-circumscribed and displayed typical morphological features of a CMF. At the periphery, there was a small area of metaplastic bone. Immunohistochemically, the tumour cells were diffusely positive for smooth muscle actin and GRM1, and negative for S100 protein, desmin and cytokeratin AE1AE3. Whole transcriptome sequencing revealed a novel PNISR::GRM1 gene fusion. Our case indicates that CMF should be included in the differential diagnosis of soft tissue (including subcutaneous) tumours composed of spindle/ovoid cells, with a lobular architecture and chondromyxoid matrix. The diagnosis of CMF arising in soft tissues can be confirmed by identifying a GRM1 gene fusion or GRM1 expression by immunohistochemistry.

• Language: English
• Keywords: chondromyxoid fibroma, extraosseous tumour, GRM1, MEF2A::ARHGAP36, PNISR::GRM1, subcutaneous tumour
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 917-921
• Numbering: Vol. 482, iss. 5
• PID: 20.500.12556/RUL-148046
• UDC: 616
• ISSN on article: 0945-6317
• DOI: 10.1007/s00428-023-03519-4
• COBISS.SI-ID: 142570499
• Publication date in RUL: 26.07.2023

Record is a part of a journal

• Title: Virchows Archiv
• Shortened title: Virchows arch.
• Publisher: Springer Nature
• ISSN: 0945-6317
• COBISS.SI-ID: 7571161

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: hondromiksoidni fibrom, zunajkostni tumor, GRM1

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P3-0054
• Name: Patologija in molekularna genetika