Dermoid cyst

Dermoid cyst Definition:

• Dermoid cyst is a benign embryonic tumor of ectodermal origin.
• Cystic/mature teratoma: Dermoid cyst which contains tissue from all 3 germ-lines

Terminology:

• Dermoid cyst, dermoid, epidermoid
• Epidermoid cyst: synonym for both a dermoid cyst and an epidermal cyst.

ICD code:

• D279

Pathogenesis:

• Origin:  arise from tissue dispersed during embryonic development due to the entrapment of ectodermal elements along the lines of embryonic closure.
• Composition:
  • Capsule: coarse, the surface smooth and shiny.
  • Contents: Pronounced variability of 3 germ-line derivatives with regard to their differentiation
    • Often contain hair, teeth, adnexa, bones, or fat  (contents are oily at 37 ° C, pasty at room temperature → keratinized debris can often be expressed as a cheesy mass after incision)
  • Microscopy: The following structures are randomly mixed up and embedded in loose connective tissue:

• • • +/- Granulomatous inflammation: granulomatous inflammation with foreign body giant cells develops when the contents of the cyst penetrate the soft tissue

Dermoid cyst types as per the Localization:

Clinical manifestations:

Complication:

• Malignant degeneration is possible → carcinomas of the squamous epithelium, malignant melanomas or sarcomas.

Dx:

• CT: dermoid of CNS appear non- contrasting and hypodense → can grow around the surrounding brain tissue.
• MRI: show a signal intensity similar to that of CSF (confused with enlarged cisterns)
• Diffusion-weighted imaging sequence (DWI-MRI):  appear light and the liquor appear dark are used for the differential diagnosis.

Ddx:

1. Epidermal cysts, but they usually have not been around since the birth
2. Subcutaneous hemangiomas
3. Gliomas and other congenital malformations of the central nervous system
4. Other ovarian tumors

Rx:

1. Should be excised in toto.
2. Must be taken into account that connections to deeper-lying structures (orbit or neural structures) even with superficial localization on the skin.

MCQs:

• Dermoid arises from?

1. 1. Pluripotent cell
   2. Totipotent cell
   3. Ectoderm
   4. Mesoderm

• What is the most probable diagnosis based on the given image?

​​​

1. 1. Dermoid cyst
   2. Sebaceous cyst
   3. Lipoma
   4. Hemangioma

Also read:

1. Dermoid Cyst by Shahjahan Shareef; Leila Ettefagh

Also Watch:

• Dermoid Cyst: 5-Minute Pathology Pearls

• Dermoid cyst scalp excision by Dr. Pandiaraja
• Dermoid Cyst Ablation 2D

References:

1. Prior A, Anania P, Pacetti M, Secci F, Ravegnani M, Pavanello M, Piatelli G, Cama A, Consales A. Dermoid and Epidermoid Cysts of Scalp: Case Series of 234 Consecutive Patients. World Neurosurg. 2018 Dec;120:119-124.
2. Sorenson EP, Powel JE, Rozzelle CJ, Tubbs RS, Loukas M. Scalp dermoids: a review of their anatomy, diagnosis, and treatment. Childs Nerv Syst. 2013 Mar;29(3):375-80.
3. Brownstein MH, Helwig EB. Subcutaneous dermoid cysts. Arch Dermatol. 1973 Feb;107(2):237-9.
4. Pryor SG, Lewis JE, Weaver AL, Orvidas LJ. Pediatric dermoid cysts of the head and neck. Otolaryngol Head Neck Surg. 2005 Jun;132(6):938-42.