Hybrid granular cell tumor/perineurioma: a report of two rare cases with PIK3CA mutations.

in Virchows Archiv : an international journal of pathology by Ani Toklu, Gauri Panse, George Jour, Konstantinos Linos, Jeffrey M Cloutier, Carina A Dehner

TLDR

  • Two rare cases of hybrid granular cell tumor-perineurioma were reported, featuring pathogenic PIK3CA mutations and distinct immunohistochemical profiles.
  • The study provides the first molecular data on these unusual neoplasms and expands on the clinical and pathologic spectrum.

Abstract

Hybrid peripheral nerve sheath tumors (PNSTs) are rare mesenchymal neoplasms with dual differentiation, most often combining two of the three main PNST types: schwannoma, neurofibroma, and perineurioma. Recognized by the WHO since 2013, these tumors can also exhibit fewer common combinations, such as hybrid granular cell tumor/perineurioma. We herein report two rare cases of hybrid granular cell tumor perineurioma with molecular analysis. Both tumors presented as dermal to subcutaneous, well-circumscribed lesions composed of a combination of spindled and granular cell components. By immunohistochemistry, the granular cells were positive for S100, SOX10, and CD68, while the perineurial cells were highlighted by EMA and GLUT1 stains. Subsequent molecular testing revealed pathogenic mutations involving PIK3CA in both cases. Our study expands on the clinical and pathologic spectrum and provides the first molecular data on these unusual neoplasms. Further, we provide a comprehensive review of the literature of all previously reported cases and briefly discuss relevant differential diagnoses and their molecular features.

Overview

  • This study reports two rare cases of hybrid granular cell tumor-perineurioma, a rare type of peripheral nerve sheath tumor with dual differentiation.
  • The cases presented as dermal to subcutaneous, well-circumscribbed lesions composed of a combination of spindled and granular cell components.
  • The primary objective of the study is to provide molecular data on these unusual neoplasms and expand on the clinical and pathologic spectrum.

Comparative Analysis & Findings

  • The study analyzed two rare cases of hybrid granular cell tumor-perineurioma and found both tumors to have pathogenic mutations involving PIK3CA.
  • The immunohistochemical analysis revealed that the granular cells were positive for S100, SOX10, and CD68, while the perineurial cells were highlighted by EMA and GLUT1 stains.
  • The study expands on the clinical and pathologic spectrum of these tumors and provides the first molecular data on these unusual neoplasms.

Implications and Future Directions

  • The study provides valuable insights into the molecular mechanisms underlying these tumors, which may aid in the development of targeted therapies.
  • Further studies are needed to elucidate the precise role of PIK3CA mutations in the development and progression of these tumors.
  • The study highlights the importance of comprehensive molecular testing in the diagnosis and management of these rare tumors.
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