PIK3CA mutation in a case of CTNNB1 mutant sinonasal glomangiopericytoma

CD34-Positive Spindle Cell Tumor With CTNNB1 Mutation: An Unusual Spindle Cell Variant of Sinonasal Glomangiopericytoma

Sinonasal glomangiopericytoma is an uncommon mesenchymal tumor with a perivascular myoid phenotype, which is categorized as a borderline/low-grade malignant soft tissue tumor by the current World Health Organization Classification of Head and Neck tumors. Here, we present the case of a 53-year-old woman with an unusual spindle cell morphology of sinonasal glomangiopericytoma arising in the nasal cavity, mimicking solitary fibrous tumor. Microscopically, the tumor showed a cellular proliferation of spindle cells in fascicles including a focal long sweeping arrangement or whorls, or with a storiform growth pattern, associated with hemangiopericytoma-like gaping blood vessels embedded in a fibrous stroma. This arrangement of the spindle cells faintly indicated a solitary fibrous tumor rather than sinonasal glomangiopericytoma. Immunohistochemically, the tumor was positively reactive to not only beta-catenin (in the nuclei) but also CD34, although signal transducers and activators of transcription 6 was negative. Mutational analysis using Sanger sequencing detected a CTNNB1 mutation. We finally diagnosed the tumor as a sinonasal glomangiopericytoma, showing an unusual spindle cell variant. Such unusual spindle cell morphology with CD34-immunoreactivity potentially leads to an incorrect diagnosis of solitary fibrous tumor because such prominent fascicles including long sweeping structures, reminiscent of desmoid-type fibromatosis, have scarcely been described in the literature. Hence, careful morphological scrutiny using appropriate diagnostic adjuncts is necessary for correct diagnosis.

International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors

BACKGROUND

Sinonasal neoplasms, whether benign and malignant, pose a significant challenge to clinicians and represent a model area for multidisciplinary collaboration in order to optimize patient care. The International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors (ICSNT) aims to summarize the best available evidence and presents 48 thematic and histopathology-based topics spanning the field.

METHODS

In accordance with prior International Consensus Statement on Allergy and Rhinology documents, ICSNT assigned each topic as an Evidence-Based Review with Recommendations, Evidence-Based Review, and Literature Review based on the level of evidence. An international group of multidisciplinary author teams were assembled for the topic reviews using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format, and completed sections underwent a thorough and iterative consensus-building process. The final document underwent rigorous synthesis and review prior to publication.

RESULTS

The ICSNT document consists of four major sections: general principles, benign neoplasms and lesions, malignant neoplasms, and quality of life and surveillance. It covers 48 conceptual and/or histopathology-based topics relevant to sinonasal neoplasms and masses. Topics with a high level of evidence provided specific recommendations, while other areas summarized the current state of evidence. A final section highlights research opportunities and future directions, contributing to advancing knowledge and community intervention.

CONCLUSION

As an embodiment of the multidisciplinary and collaborative model of care in sinonasal neoplasms and masses, ICSNT was designed as a comprehensive, international, and multidisciplinary collaborative endeavor. Its primary objective is to summarize the existing evidence in the field of sinonasal neoplasms and masses.