Orbital Sarcoma with BCOR Genetic Alterations in the Pediatric Age Group

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Pediatric orbital tumors present a diagnostic challenge due to overlapping histology, particularly malignant small round cell tumors.
• BCOR genetic alterations define a specific subtype of undifferentiated round cell sarcomas (URCS) with unique clinical and pathological features.
• These BCOR-altered sarcomas have not been previously recognized in the orbit, increasing the risk of misdiagnosis.

Purpose of the Study:

• To report the occurrence and characteristics of orbital sarcomas associated with BCOR genetic alterations in pediatric patients.
• To highlight the importance of considering novel genetically defined entities in the differential diagnosis of pediatric orbital URCS.

Main Methods:

• Case series describing two pediatric patients with orbital sarcomas.
• Histopathological examination of tumor specimens, including cellular morphology and stromal characteristics.
• Immunohistochemical analysis for BCOR, cyclin D1, and SATB2.
• Assessment for BCOR rearrangements or internal tandem duplications.

Main Results:

• Two pediatric female patients, aged 8 and 16 months, presented with proptosis.
• Tumors exhibited sheets of round to ovoid cells with monomorphic nuclei and frequent mitoses.
• Absence of delicate branching capillaries and myxoid stroma was noted.
• Immunohistochemistry revealed diffuse positivity for BCOR, cyclin D1, and SATB2.

Conclusions:

• Orbital sarcomas with BCOR genetic alterations are exceptionally rare in pediatric patients.
• Pathologists must maintain a high index of suspicion for these rare entities.
• Accurate diagnosis necessitates appropriate ancillary genetic testing for BCOR alterations in suspected pediatric orbital URCS.