A dermoid cyst is a benign cutaneous developmental anomaly that arises from the entrapment of ectodermal elements along the lines of embryonic closure. These benign tumors are lined by stratified squamous epithelium with mature skin appendages found on their wall and their lumens filled with keratin and hair. Dermoid cysts are considered to be congenital, but not all of them are diagnosed at birth. Only about 40% of dermoid cysts are diagnosed at birth, while about 60% of the dermoid cysts are diagnosed by five years of age. The dermoid cysts usually present within the first year of life and grow slowly.[1] Dermoid cysts occur most commonly on the head and neck, with 84% of these cysts occurring in this region.
The etiology of dermoid cysts remains mostly unknown. The cause of this congenital developmental anomaly has yet to be determined. Dermoid cysts are true hamartomas. These occur when skin and skin structures become trapped during fetal development. Prior et al. did not find any correlation between the localization of the dermoid cyst and sex, histology, or age of the patient.[Treatment / Management
Dermoid cysts usually tend to grow slowly, further having the potential to cause bony deformities, intracranial extension, or intra spinal extension. The presence of intracranial extension or intra spinal extension can further lead to meningitis or develop into an abscess. A small, asymptomatic dermoid cyst may not necessitate immediate excision as it can be stable for years or even regress. However, because most dermoid cysts grow over time, complete surgical excision without disruption of the cyst wall by an experienced surgeon is recommended before the development of such complications.
Early resection may also avoid extensive surgery and a shorter skin incision, further resulting in an improved cosmetic outcome. An additional advantage of surgical excision is the possibility of obtaining a histologic diagnosis due to the rare possibility of a malignant tumor presenting as a solitary lump in the head and neck region of a child like a dermoid cyst .The most dermoid cysts can be removed using a direct approach with careful dissection at the site where the cyst adheres to the bone. If the cyst wall ruptures at the time of surgical removal, then remnant tissue should be removed using curettage and copious irrigation.
If the cyst wall has adhered to vital structures, a partial excision may be performed. Recurrences of dermoid cyst have been seen in cases of incomplete excision. Another benefit of early removal of dermoid cysts is a higher chance of obtaining a complete excision without disruption of the cyst wall, a factor associated with a reduced risk of recurrence. For small dermoid cysts, endoscopic surgery is a novel approach for removal .In cases of a dermoid cyst with intracranial extension, a craniotomy may still be required.
Differential Diagnosis
Dermoid cysts are rare, but all nodular cyst like lesions are included in the differential diagnoses of a patient presenting with a subcutaneous nodule, especially in the head and neck or midline region. Following are the differentials of a dermoid cyst:
Epidermoid cyst
Glioma
Encephalocele
Juvenile xanthogranuloma
Lipoma
Pilar cysts
Meningioma
Neurofibroma
Teratoma
Rhabdomyosarcoma
Olfactory neuroblastoma
Lymphoma
Subcutaneous abscess
Facial trauma
Trichilemmal cyst
Pilomatrixoma
Lymphatic malformation
Thyroglossal duct cyst