title: Fluid-fluid level in a giant epidermal cyst of the buttock.
abstract: We describe a case of a giant epidermal cyst of the buttock that demonstrated a fluid-fluid level on imaging. There have been no previously reported cases of epidermal cysts containing a fluid-fluid level, so our case was considered to be very exceptional. A 39-year-old man had had a slowly enlarging giant subcutaneous mass in the left buttock for more than 10 years. It was elastic-soft, well-circumscribed and smooth-surfaced. Ultrasonography showed a well-circumscribed hypoechoic mass with a fluid-fluid level in the subcutis of the left buttock. Magnetic resonance imaging (MRI) showed a well-circumscribed cystic mass measuring 8 cm x 5.5 cm x 5.5 cm in the same place that the ultrasonography indicated. It was hypointense on the T1-weighted image, hyperintense on the T2-weighted image, and contained a fluid-fluid level on both the T1- and T2-weighted images. It bordered on the anus, but neither adhered nor formed a fistula with it. A surgical excision was performed. The mass was diagnosed histopathologically as an epidermal cyst. The occurrence of fluid-fluid levels in epidermal cysts should be kept in mind in the differential diagnosis of subcutaneous soft tissue tumors.
authors.affiliation: Division of Dermatology, Higashi-Ohmi Keiai Hospital, Yokaichi, Higashi-Ohmi, Japan. takemura@keiaikai.or.jp
authors.forename: Noriko
authors.initials: N
authors.lastname: Takemura
authors.forename: Norikazu
authors.initials: N
authors.lastname: Fujii
authors.forename: Chikako
authors.initials: C
authors.lastname: Shibata
authors.forename: Akiko
authors.initials: A
authors.lastname: Kawano
authors.forename: Noriki
authors.initials: N
authors.lastname: Fujimoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Uenishi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D002081:Buttocks / Q000473:pathology; D020420:Cyst Fluid; D004814:Epidermal Cyst / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D040521:Subcutaneous Tissue / Q000000981:diagnostic imaging / Q000473:pathology*; D014463:Ultrasonography