Recurrent Sinonasal CD34-Negative Malignant Solitary Fibrous Tumor Diagnosed on STAT6 Immunohistochemistry and NAB2-STAT6 Fusion
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A spectrum of mesenchymal neoplasms occur in the sinonasal region. One of these is solitary fibrous tumor (SFT), a translocation-associated neoplasm characterized by NAB2-STAT6 gene fusion. Sinonasal SFTs characteristically display CD34 immunopositivity, which aids in diagnosis. However, a small proportion of SFTs may be negative for CD34, making diagnosis difficult. The availability of STAT6 immunohistochemistry (IHC) has helped to overcome this. Malignant SFTs, characterized by increased cellularity and mitoses > 4 per ten high power fields, are extremely unusual in the sinonasal region, with only ten such cases reported to date. We report a case of a CD34-negative malignant SFT that was diagnosed using STAT6 IHC and confirmed by demonstrating NAB2 ex 4-STAT6 ex 2 fusion, and recurred 8 months after complete excision, to highlight the aggressive nature of this tumor.
KeywordsSpindle cell tumor Nose Hemangiopericytoma Solitary fibrous tumor STAT6
The authors are grateful to the Division of Molecular Pathology, Department of Pathology, Tata Memorial Centre, Mumbai, India for performing molecular testing for NAB2-STAT6 fusion.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article is a case report and does not contain any studies with human participants or animals performed by any of the authors.
Informed consent was obtained from the patient included in the study.
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