Dermoid Cyst of the Superolateral Preseptal Orbit in a Child: Ultrasound, MRI, and Histopathological Correlation

Orbital dermoid cysts are benign congenital lesions that commonly arise along embryonic suture lines, particularly in the superolateral orbit. We report a case of a four-year-old boy presenting with a painless, progressively enlarging right superolateral orbital mass. Ultrasonography demonstrated a well-defined cystic lesion with heterogeneous hypoechoic content and fine internal echogenic foci, producing the characteristic "sack of marbles" appearance, with no significant internal vascularity on color Doppler imaging. Magnetic resonance imaging revealed a well-circumscribed superolateral preseptal orbital lesion with high signal intensity on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images, diffusion restriction, and no appreciable internal post-contrast enhancement. The lesion was surgically excised, and histopathological examination confirmed the diagnosis of dermoid cyst. This case highlights the complementary roles of ultrasonography and magnetic resonance imaging in the diagnosis, anatomical localization, and pre-operative assessment of pediatric orbital dermoid cysts.