A 10-year-old girl presents with rapidly progressive unilateral proptosis over 4 weeks, with periorbital swelling and ecchymosis. CT shows an irregular, ill-defined extraconal mass in the superonasal orbit with bone destruction. Biopsy shows sheets of small round blue cells positive for desmin and myogenin. The MOST common primary malignant orbital tumor of childhood is:

• A Embryonal rhabdomyosarcoma ✓
• B Alveolar soft part sarcoma
• C Neuroblastoma metastasis
• D Ewing sarcoma

Explanation

Orbital rhabdomyosarcoma is the most common primary malignant orbital tumor of childhood, typically presenting as rapid proptosis in the first decade. Desmin and myogenin positivity confirms skeletal muscle differentiation, and the embryonal type predominates in the orbit. Neuroblastoma is a common metastatic tumor but not primary, and Ewing sarcoma rarely presents primarily in the orbit.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.