Small Biopsy Samples: Are They Representative for Biphenotypic Sinonasal Sarcoma?

Area of Science:

• Pathology
• Oncology
• Genetics

Background:

• Biphenitional sinonasal sarcoma (BSNS) is a rare, low-grade neoplasm affecting the sinonasal tract.
• BSNS exhibits characteristic PAX3 gene rearrangements and demonstrates both myogenic and neural differentiation.

Purpose of the Study:

• To detail the histologic, immunohistochemical, and molecular characteristics of BSNS.
• To provide diagnostic clues for identifying BSNS from small incisional biopsies.

Main Methods:

• Retrospective analysis of archival sinonasal tumor samples.
• Histologic examination and immunohistochemistry (S100, SMA, SOX10, PAX3) on biopsy and resection specimens.
• Fluorescence in situ hybridization (FISH) for PAX3 and SS18 rearrangements on biopsy samples.

Main Results:

• Six cases of BSNS were identified and confirmed.
• PAX3 rearrangement was detected by FISH in 5 of the 6 cases.
• Immunohistochemical staining patterns were consistent between paired biopsy and resection samples in most cases.

Conclusions:

• Small incisional biopsies are generally sufficient for BSNS diagnosis.
• Morphological assessment combined with S100, SOX10, and SMA immunohistochemistry serves as a reliable screening method.
• PAX3 rearrangement analysis is crucial for diagnosis in cases with atypical morphology or immunoprofile.