Subconjunctival Fat Prolapse and Dermolipoma of the Orbit: Differentiation on CT and MR Imaging

Abstract

BACKGROUND AND PURPOSE:Subconjunctival fat prolapse and dermolipoma of the orbit are unfamiliar to radiologists and yet should be differentiated because their treatments are different. The purpose of this study was to investigate the CT and MR imaging findings that distinguish these 2 conditions.

Inferomedial Dermolipoma With Ectopic Lacrimal Gland

“…2 In the largest series to date, Fry et al 1 describe 45 patients with dermolipomas, all of which were found to arise temporally. Mcnabb et al 2 and Kim et al 3 also found the dermolipoma to be in the temporal orbit in all patients studied in their series of 35 and 27 patients, respectively. Maeng et al 4 describe the only case we could find in the literature of a dermolipoma occurring medially and anterior to the palpebral conjunctiva that presented as a palpable right lower eyelid mass.…”

Diagnosis and Excision of Subconjunctival Herniation of Orbital Fat

“…1Y3 This weakening of the Tenon capsule allows the intraconal orbital fat to protrude anteriorly and can occur unilaterally or bilaterally. 5,6 Patients often present with cosmetic complaints and may also experience symptoms of dryness or discomfort. 2,4 If the lesion is large enough, it may cause formation of corneal dellen (distinct areas of corneal tissue thinning because of dehydration) secondary to exposure keratopathy.…”

“…1 It typically manifests as a yellowcolored mass located superotemporal beneath the conjunctival tissue. 1,4,5 Subconjunctival HOF is assumed to occur because of a dehiscence of the Tenon capsule whether caused by age, injury, or surgery. 1Y3 This weakening of the Tenon capsule allows the intraconal orbital fat to protrude anteriorly and can occur unilaterally or bilaterally.…”

“…7 Although subconjunctival HOF is considered a benign lesion, it does mimic several other ocular conditions such as dermolipoma, pleomorphic lipoma, atypical lipomatous tumor, conjunctival lymphoma, and lacrimal gland prolapse. 1,5,6 Differentiation between these lesions requires detailed examination with biomicroscopy, computed tomography (CT) or magnetic resonance imaging (MRI), and laboratory analysis of a biopsy specimen with light microscopy. 1,5,6 Management of subconjunctival HOF involves one of two things: observation or surgical treatment.…”

“…1,5,6 Differentiation between these lesions requires detailed examination with biomicroscopy, computed tomography (CT) or magnetic resonance imaging (MRI), and laboratory analysis of a biopsy specimen with light microscopy. 1,5,6 Management of subconjunctival HOF involves one of two things: observation or surgical treatment. 1,2,5 If the lesion does not interfere with function or cause any cosmetic concerns, it can be left alone and monitored yearly for any changes.…”