Slow-growing subdermal cyst that contains keratin and is lined by stratified squamous epithelium
Most cysts are due to ductal blockage of hair follicles with downward rupture of obstructed pilosebaceous unit
Some cysts are due to traumatic or embryological subdermal sequestration of epithelial tissue
Histologically similar and hence grouped under general term "epidermoid cyst"
Wall of cyst must not contain dermal elements
Presence of dermal elements → designation as dermoid cyst
Epidermis = outer layers of skin
Contains keratinocytes, corneocytes, and melanocytes
Dermis = inner layers of skin that support epidermis
Contains hair follicles, nerves, sweat glands, small blood vessels, and sebaceous glands
IMAGING
General Features
Radiographic Findings
CT Findings
MR Findings
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Selected References
Clarke R et al: Twinkle artefact in the ultrasound diagnosis of superficial epidermoid cysts. Ultrasound. 24(3):147-153, 2016
Park HJ et al: Strain elastography features of epidermoid tumours in superficial soft tissue: differences from other benign soft-tissue tumours and malignant tumours. Br J Radiol. 88(1050):20140797, 2015
Hung EH et al: Pitfalls in ultrasonography of soft tissue tumors. Semin Musculoskelet Radiol. 18(1):79-85, 2014
Hung EH et al: Ultrasound of musculoskeletal soft-tissue tumors superficial to the investing fascia. AJR Am J Roentgenol. 202(6):W532-40, 2014
Yuan WH et al: Differences in sonographic features of ruptured and unruptured epidermal cysts. J Ultrasound Med. 31(2):265-72, 2012
Slow-growing subdermal cyst that contains keratin and is lined by stratified squamous epithelium
Most cysts are due to ductal blockage of hair follicles with downward rupture of obstructed pilosebaceous unit
Some cysts are due to traumatic or embryological subdermal sequestration of epithelial tissue
Histologically similar and hence grouped under general term "epidermoid cyst"
Wall of cyst must not contain dermal elements
Presence of dermal elements → designation as dermoid cyst
Epidermis = outer layers of skin
Contains keratinocytes, corneocytes, and melanocytes
Dermis = inner layers of skin that support epidermis
Contains hair follicles, nerves, sweat glands, small blood vessels, and sebaceous glands
IMAGING
General Features
Radiographic Findings
CT Findings
MR Findings
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Selected References
Clarke R et al: Twinkle artefact in the ultrasound diagnosis of superficial epidermoid cysts. Ultrasound. 24(3):147-153, 2016
Park HJ et al: Strain elastography features of epidermoid tumours in superficial soft tissue: differences from other benign soft-tissue tumours and malignant tumours. Br J Radiol. 88(1050):20140797, 2015
Hung EH et al: Pitfalls in ultrasonography of soft tissue tumors. Semin Musculoskelet Radiol. 18(1):79-85, 2014
Hung EH et al: Ultrasound of musculoskeletal soft-tissue tumors superficial to the investing fascia. AJR Am J Roentgenol. 202(6):W532-40, 2014
Yuan WH et al: Differences in sonographic features of ruptured and unruptured epidermal cysts. J Ultrasound Med. 31(2):265-72, 2012
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