title: Interlabial masses in little girls: review and imaging recommendations.
abstract: When an interlabial mass is seen on physical examination in a little girl, there is often confusion about its etiology, its implications, and what should be done next. Five common interlabial masses, which superficially are strikingly similar, include a prolapsed ectopic ureterocele, a prolapsed urethra, a paraurethral cyst, hydro-(metro)colpos, and rhabdomyo sarcoma of the vagina (botryoid sarcoma). A prolapsed ectopic ureterocele occurs in white girls as a smooth mass which protrudes from the urethral meatus so that urine exits circumferentially. A prolapsed urethra occurs in black girls and resembles a donut with the urethral meatus in the center. A paraurethral cyst is smaller and displaces the meatus, so that the urinary stream is eccentric. Hydro(metro)colpos from hymenal imperforation presents as a smooth mass that fills the vaginal introitus, as opposed to the introital grapelike cluster of masses of botryoid sarcoma. Recommendations for efficient imaging are presented.
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003560:Cysts / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D005831:Genital Diseases, Female / Q000000981:diagnostic imaging*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D010808:Physical Examination; D044469:Racial Groups; D011859:Radiography; D012208:Rhabdomyosarcoma / Q000000981:diagnostic imaging; D014518:Ureterocele / Q000000981:diagnostic imaging; D014522:Urethral Diseases / Q000000981:diagnostic imaging; D014591:Uterine Diseases / Q000000981:diagnostic imaging; D014623:Vaginal Diseases / Q000000981:diagnostic imaging; D014625:Vaginal Neoplasms / Q000000981:diagnostic imaging