Tumours, masses and neoplasia
Choristomas
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Get access- Non-neoplastic tumour of normal (ectodermal) tissues in an abnormal location
Dermoid cyst
- Composed of fat, fibrous tissue, hair follicles, sweat glands (ectodermal elements).
Congenital
- May be the most common orbital tumours in children
- Due to entrapment of embryonic epithelial nests in a suture line during embryogenesis
- Keratinized stratified squamous epithelium
- No malignant potential
- Typically found in the superotemporal quadrant (frontozygomatic suture) or superomedially (frontoethmoidal suture)
- May be:
- Outside the orbital rim
- Inside the orbit
- Straddle the suture line
- Bulbar conjunctival (limbal) dermoids: well-defined, white-pale yellow lesions
- Associated with Goldenhar’s syndrome
Presentation
- Painless
- Diplopia if deep
- Slowly enlarge with age
- On CT: well-circumscribed lesion with hyperdense wall and hypodense contents (there may be an oil/water interface visible within)
- Imaging is only needed if there is uncertainty about extent/nature of lesion
Treatment
- Typically surgical excision
- A lipogranulomatous reaction may occur if the cyst ruptures or if incompletely removed
Dermolipomas
- Phakomatous choristoma: eyelid nodule composed of lens capsular material!