Overview
What is a trichilemmal cyst (pilar cyst)?
What is the pathophysiology of trichilemmal cyst (pilar cyst)?
What causes trichilemmal cyst (pilar cyst)?
What is the prevalence of trichilemmal cyst (pilar cyst) in the US?
What are the racial predilections of trichilemmal cyst (pilar cyst)?
What are the sexual predilections of trichilemmal cyst (pilar cyst)?
Which age group is at highest risk for trichilemmal cyst (pilar cyst)?
What is the prognosis of trichilemmal cyst (pilar cyst)?
Presentation
Which clinical history findings are characteristic of trichilemmal cyst (pilar cyst)?
Which physical findings are characteristics of trichilemmal cyst (pilar cyst)?
What are the possible complications of trichilemmal cyst (pilar cyst)?
DDX
What are the differential diagnoses for Trichilemmal Cyst (Pilar Cyst)?
Workup
What is the role of imaging studies in the diagnosis of trichilemmal cyst (pilar cyst)?
What is the role of excision in the evaluation of trichilemmal cyst (pilar cyst)?
Which histologic findings are characteristic of trichilemmal cyst (pilar cyst)?
Treatment
What are indications of infection in a trichilemmal cyst (pilar cyst)?
How is trichilemmal cyst (pilar cyst) treated?
Medications
What is the role of medications in the treatment of trichilemmal cyst (pilar cyst)?
-
A firm, smooth swelling on the scalp.
-
Surgical removal of an intact pilar cyst through an elliptical excision.
-
Closure of the defect after surgical removal of the pilar cyst.
-
The trichilemmal cyst is lined by a squamous epithelium without a granular layer and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin.
-
At higher magnification, the cyst is lined by a squamous epithelium without a granular layer and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin.
-
Numerous cholesterol clefts are identified within the homogenous keratin of the trichilemmal cyst.
-
Pilar cyst, low power. The trichilemmal cyst is lined by squamous epithelium without a granular layer (trichilemmal keratinization) and with swelling of the cells close to the cyst cavity, which is filled with homogenous keratin. Calcifications are a common feature.
-
Pilar cyst, medium magnification. Higher magnification shows the stratified squamous epithelium without a granular layer and shows swelling of the cells closest to the cyst cavity.
-
Ruptured pilar cyst. A ruptured trichilemmal cyst showing replacement of the squamous lining by histiocytes and rare multinucleated giant cells.
-
Ruptured, low power. Another ruptured trichilemmal cyst showing replacement of the epithelial lining by granulomatous reaction with numerous cholesterol clefts and calcifications.
-
Ruptured, high power. Higher-power image highlighting the cholesterol clefts and calcifications.