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GTF2I mutation in micronodular thymoma with lymphoid stroma
  1. Andrea Bille1,
  2. Katherine Fryer2,
  3. Andrew Wallace2,
  4. Daisuke Nonaka3
  1. 1 Department of Thoracic Surgery, Guy's and St Thomas' Hospitals NHS Foundation Trust, London, UK
  2. 2 Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Manchester, UK
  3. 3 Department of Cellular Pathology, Guy's and St Thomas' Hospitals NHS Foundation Trust, London, UK
  1. Correspondence to Dr Daisuke Nonaka, Cellular Pathology, Guy's and St Thomas' Hospitals NHS Trust, London, SE1 7EH, UK; DNonaka{at}


Aims Micronodular thymoma with lymphoid stroma is a rare subtype of thymoma with characteristic clinical and pathological features. Some of the features, such as indolent nature, principally spindle morphology and no significant association to myasthenia gravis, are shared with type A and AB thymoma, which is closely linked to GTF2I mutation. However, not much is known regarding the molecular genetics of this thymoma subtype. In this study, the GTF2I mutation status was investigated in 16 cases of micronodular thymoma.

Methods 16 micronodular thymomas were retrieved and the GTF2I mutation was tested by Sanger sequencing. The clinicopathological findings were documented.

Results GTF2I c.1271T>A p.(Leu424His) mutation within exon 15 was detected in 14 out of 16 tumours (87.5%). Two patients died of other causes while all others remained alive with no evidence of recurrence during the follow-up period ranging from 19 to 188 months (median: 100 months).

Conclusions GTF2I mutation status and presence of spindle cell morphology may indicate that type A and AB thymoma, and micronodular thymoma represent a group biologically distinct from type B thymomas, which generally lack this mutation.

  • Morphological and Microscopic Findings

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • Handling editor Runjan Chetty.

  • Contributors DN performed study concept and design; DN, KF, AW and AB performed development of methodology and writing, review and revision of the paper; DN and AB provided acquisition, analysis and interpretation of data, and statistical analysis; KF and AW provided technical and material support; DN as a guarantor. All authors read and approved the final paper.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.