Orbital Teratoma in an Adult: A Case Report and Literature Review.

Orbital teratomas are rare congenital tumors that are typically diagnosed in infancy due to rapidly progressive proptosis. Adult-onset orbital teratomas are exceedingly rare, with only a few cases reported in the literature. We present the case of a 24-year-old man who developed progressive right-sided proptosis and diplopia. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a well-circumscribed mass in the superolateral right orbit containing areas of fat attenuation without calcification or bony erosion. The tumor was completely resected via a frontotemporal craniotomy. Histopathological examination revealed mature tissues derived from all three germ layers: ectodermal (nerve bundles), mesodermal (adipose tissue and vascular elements), and endodermal (salivary gland-like glandular tissue). These findings confirmed the diagnosis of a mature teratoma. At six-month follow-up, there was no radiologic or clinical evidence of recurrence, and ocular motility had markedly improved. This case illustrates the diagnostic challenges of distinguishing adult-onset orbital teratoma from other fat-containing orbital lesions, such as dermoid cysts or lipomas. It also demonstrates that, when the lesion extends into the superolateral orbit, a frontotemporal craniotomy provides safe and complete resection with favorable functional and cosmetic outcomes.