Orbital Tumors - Herniated Orbital Fat

General

• Prolapse of subconjunctival intraconal orbital fat
• First described in pathology literature in 2007 (Am J Surg Pathol 2007;31:193)

Clinical features

• Rarely causes an intraorbital mass lesion
• Mean age 66 years, 90% men
• Prolapse is usually into superotemporal quadrant or lateral canthus
• Usually due to orbital fat herniation through a dehiscence in Tenon's capsule
• Manifests as unilateral or bilateral yellowish mass
• Does not recur

Differential diagnosis

• Pleomorphic lipoma: different clinical presentation; aggregates of bland spindle cells, floret cells and wiry collagen
• Well differentiated liposarcoma: different clinical presentation; enlarged hyperchromatic cells within fibrous septae