Distinguishing a Trichilemmal Cyst From a Pilomatricoma With Ultrasound

Abstract

Objectives-To determine whether ultrasound (US) could distinguish a trichilemmal cyst from a pilomatricoma preoperatively. Methods-Ultrasound images of 61 pathologically proven trichilemmal cysts and 90 pathologically proven pilomatricomas were analyzed retrospectively. Two radiologists evaluated several US features. The sensitivity, specificity, Youden index, and predictive values of statistically significant US features were assessed. Parallel combined tests, serial combined tests, or both were performed to identify US features with high statistical significance. Results-Results from individual US features were not satisfactory; however, serial combined tests that included absence of complete internal echogenic foci, absence of a hypoechoic rim, absence of peritumoral hyperechogenicity, and absence of vascularity showed higher diagnostic utility. The sensitivity, specificity, Youden index, positive predictive value, and negative predictive value for correctly identifying a trichilemmal cyst were 74%, 88%, 0.62, 80%, and 83%, respectively. If 1 of these 4 US features was not a match for a trichilemmal cyst, pilomatricoma was considered. Conclusions-It may be possible to distinguish trichilemmal cysts from pilomatricomas preoperatively using US. A combined test is superior to using any individual US feature.

Ultrasonographic Spectrum of Cutaneous Cysts With Stratified Squamous Epithelium in Pediatric Dermatology: Pictorial Essay

“…They appear as well‐defined, round or ovoid, sometimes lobulated, hypoechoic, anechoic, or more often heterogeneous avascular lesions with or without posterior acoustic enhancement 1,15 . They are usually located in the dermal–epidermal junction and part of the hypodermis, and may present a thinning of the overlying dermis 1,15 . Echogenicity may vary depending on cyst content 1 .…”

“…Echogenicity may vary depending on cyst content 1 . Internal echogenic foci represent calcification, cholesterol crystals, or both (Figure 5, A and B) 15 …”

“…1,15 They are usually located in the dermalepidermal junction and part of the hypodermis, and may present a thinning of the overlying dermis. 1,15 Echogenicity may vary depending on cyst content. 1 Internal echogenic foci represent calcification, cholesterol crystals, or both (Figure 5, A and B).…”

“…1 Internal echogenic foci represent calcification, cholesterol crystals, or both (Figure 5, A and B). 15 The differential diagnosis includes epidermoid cyst, dermoid cyst, and pilomatrixoma. Even though some authors report it is impossible to distinguish between epidermoid and trichilemmal cysts, 1 others argue that they can be differentiated because trichilemmal cysts locate mainly on the scalp, do not have a connecting tract (punctum), and may contain scattered dotlike and lumplike/arc-shaped calcifications inside, whereas only a few epidermoid cysts may contain internal linear calcifications.…”

A rare ossifying trichilemmal cyst in a young female patient: Case report and literature review

“…They constitute the second most common cutaneous cysts and are diagnosed mainly clinically [2,11]. Imaging modalities such as ultrasound and computerized tomography can provide additional information regarding the location and characteristics of the cyst, whereas the diagnostic confirmation is made via pathology examination of the lesion [12].…”