title: Epidermal cysts in the superficial soft tissue: sonographic features with an emphasis on the pseudotestis pattern.
abstract: OBJECTIVE
  The purposes of this study were to report the sonographic features of superficial epidermal cysts with an emphasis on the characteristic pseudotestis appearance and to highlight the spectrum of ancillary findings.
  
  
  METHODS
  The medical records and sonographic studies of all cases of surgically proven epidermal cysts (n = 42) from January 2005 through December 2009 were reviewed. Twenty-six epidermal cysts (62%) that appeared on sonography as ovoid nodules with homogeneous low to medium echoes, simulating a testicle, were included in the pseudotestis group. The other 16 epidermal cysts (38%) without the pseudotestis pattern were included in the nonpseudotestis group. The age, sex, lesion size, length to width ratio, sonographic appearances, and frequencies of rupture and infection were compared between the groups.
  
  
  RESULTS
  Epidermal cysts in the nonpseudotestis group presented as heterogeneously echoic or lobulated nodules or had a concentric ring or target appearance. There were no significant differences in the age, sex, lesion size, and length to width ratio between the groups. The pseudotestis group had significantly higher frequencies of intralesional bright echogenic reflectors and filiform anechoic areas than the nonpseudotestis group (P < .01). There were no significant differences in the associated ancillary sonographic features, including posterior acoustic enhancement, dermal attachment, focal dermal protrusion, and frequencies of rupture and infection between the groups.
  
  
  CONCLUSIONS
  In this study, two-thirds of the superficial epidermal cysts had a characteristic pseudotestis pattern on sonography, whereas the others could be suspected by recognition of the ancillary sonographic findings, including dermal attachment and focal dermal protrusion or a distinctive concentric ring or target pattern.
authors.affiliation: Department of Radiology, Chang Gung University College of Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, 123 Ta-Pei Rd, Niao-Sung Hsiang, 833 Kaohsiung Hsien, Taiwan.
authors.forename: Chung-Cheng
authors.initials: CC
authors.lastname: Huang
authors.forename: Sheung-Fat
authors.initials: SF
authors.lastname: Ko
authors.forename: Hsuan-Ying
authors.initials: HY
authors.lastname: Huang
authors.forename: Shu-Hang
authors.initials: SH
authors.lastname: Ng
authors.forename: Tze-Yu
authors.initials: TY
authors.lastname: Lee
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Lee
authors.forename: Min-Chi
authors.initials: MC
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004814:Epidermal Cyst / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D012422:Rupture, Spontaneous; D013737:Testis / Q000000981:diagnostic imaging; D014463:Ultrasonography