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Dermoids

Etiology

1. benign cystic lesions that are choristomas (tumors composed of tissues not usually found at the involved site)
2. originate at bony suture sites during embryogenesis as a lead to of surface skin elements becoming entrapped
3. usually found in early childhood (25% are noted at birth), but can also be diagnosed in adults
   • in adults, they often involve the deep orbital tissues and grow to a very large size
4. Not to be confused with Epidermoid cysts which are   similar but lack certain elements in the wall of the cyst

Differential Diagnosis

• encephalocele
• lacrimal mass/tumor
• lacrimal mass or tumor

Work-up / Course / Prognosis

CT/MRI imaging reveals characteristic round to oval shaped cystic lesion with a defined lining

Symptoms

• painless
• slow-growing

Signs

• typically do not displace the globe
• typically do not raise intraocular pressure

Locations

• occur in the superotemporal  orbit (the most common site, 70% )
• the superomedial orbit
• deep orbit

Trauma might lead to leakage of the cystic contents and likely will lead to in acute inflammation

Pathology

Lining

• the cysts are lined by keratinizing, stratified squamous epithelium (85% of lesions), or
• nonkeratinized stratified squamous epithelium

Filling

• filled with keratin
• hair shafts are usually present in lumen or wall of cyst (99%)
• sebaceous glands are usually present in lumen or wall of cyst (75%)
• sweat glands are often present in lumen or wall of cyst (20%)

Treatment

• surgical excision is the treatment of choice. With complete excision, the prognosis is excellent.
• usually once they child has reached age 12 months

Compare with EPIDERMOID