Dermoid Cyst Differential Diagnoses

Updated: Apr 16, 2019
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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DDx

Diagnostic Considerations

Pilar cysts, also known as trichilemmal cysts, are acquired rather than congenital. They tend to appear on the scalp rather than the face, and they tend to be intradermal rather than subcutaneous.

Although dermoid cysts are rare, they should be included in the differential diagnosis of all nodular cystlike lesions in the head or neck or in a midline (eg, chest midline) in infants and children. An intraoral nodular lesion or tumor of the tongue may be a dermoid cyst.

Cutaneous or lymph node lesions diagnosed as metastases of melanoma or squamous cell carcinoma may reflect other pathologic entities, especially in patients in whom the primary skin tumor could not been identified. Such lesions may represent a late clinical stage in the malignant malformation of melanocytic lesions, or may reflect a malignant squamous epithelial proliferation inside an ovarian dermoid cyst. Although these malignancies are extremely rare, they should be included in the dermatologic differential diagnosis.

The presence of a hair collar sign around a suspected dermoid cyst might indicate cranial dysraphism, such as that seen in a cutaneous ectopic brain.

A giant dermoid cyst of the neck can mimic a cystic hygroma, requiring MRI to differentiate. [34]

A retrorectal (presacral) dermoid cyst has been described in which the lining squamous epithelium showed marked expansion by Paget disease of extramammary type. [35]

A vascular leiomyoma of the extracranial scalp with a small deformity on the skull in a child may mimic a dermoid cyst. [36]

A childhood dermoid cyst may mimic a craniopharyngioma. [37]

A congenital intracranial frontotemporal dermoid cyst may be first evident as a cutaneous fistula. Intracranial extension and a cutaneous sinus tract are rarely seen with craniofacial dermoid cysts. [9] Failure to recognize and promptly treat these dermoid cysts may lead to a progressive skeletal distortion and/or recurrent infection with a potential for meningitis or cerebral abscess. Congenital lesions of the midline should always be approached with caution. Imaging studies are prudent.

Important, include dermoid cyst in the differential diagnosis of a tarsus-based eyelid nodule, because misdiagnosis may lead to incision and curettage, resulting in spillage of cyst contents and severe inflammation and scarring. [5]

Also consider intramuscular lipoma [38] and ocular adnexal racemose cysticercosis. [39]

Differential Diagnoses