A comparative study of pilomatricoma and epidermoid cyst with ultrasound

Integrating vascularity into the pattern classification of pilomatricomas on ultrasound provides a more competent approach for discriminative evaluation

“…Posterior acoustic shadowing is predominantly present in pilomatricomas and occasionally in dermatofibrosarcomas protuberans and epidermoid cysts, while posterior acoustic enhancement is predominantly present in epidermoid cysts and occasionally in pilomatricomas. These findings are consistent with previous studies 4–8,21–23 . Vascularity is typically absent in epidermoid cysts unless there is coexisting inflammation, while it is rich in dermatofibrosarcomas protuberans and frequently present in pilomatricomas 20,22,23 .…”

“…Of the hypoechoic rim, we used the criterion from the Type 2 in the study by Pelizzari et al 5 Only five pilomatricomas were found to have a hypoechoic rim (7.9%, 5/63), while there were nine epidermoid cysts with a hypoechoic rim (11.8%, 9/76) in our study, as shown in Figures 4 and 7. Therefore, the presence of a hypoechoic rim is not a unique diagnostic factor for pilomatricoma, which differs from the findings of Choo et al 6 and Wei et al 21 The reason for this discrepancy may be the variation in inter-reader agreement for identifying a hypoechoic rim.…”

“…19 However, typical epidermoid cysts with uncommon features may be mistaken for other lesions. 20,21 In our study, there were five epidermoid cysts with the fistula sign or submarine sign and one epidermoid cyst with an ambiguous onion sign, and these features did not appear in pilomatricomas and dermatofibrosarcomas protuberans.…”

“…Scattered punctate hyperechoic foci or dots are predominantly present in pilomatricomas, but they can also appear in epidermoid cysts and dermatofibrosarcomas protuberans. 21 The echogenic texture of pilomatricomas is predominantly heterogeneous due to the presence of calcification and other changes, while epidermoid cysts and dermatofibrosarcomas protuberans mainly present as homogenous echogenicity. The presence of scattered punctate hyperechoic foci alone is not sufficient to support the differential diagnosis, as there can be overlap of these features.…”

“…These findings are consistent with previous studies. [4][5][6][7][8][21][22][23] Vascularity is typically absent in epidermoid cysts unless there is coexisting inflammation, while it is rich in dermatofibrosarcomas protuberans and frequently present in pilomatricomas. 20,22,23 In our study, two epidermoid cysts were mistaken as pilomatricoma and inflammatory lesions.…”