title: Plunging Ranulas Revisited: A CT Study with Emphasis on a Defect of the Mylohyoid Muscle as the Primary Route of Lesion Propagation.
abstract: OBJECTIVE
  The purpose of this study was to clarify the pathogenesis of plunging ranulas in regard of the pathway of lesion propagation using CT scans.
  
  
  METHODS
  We retrospectively reviewed CT scans of 41 patients with plunging ranula. We divided plunging ranulas into two types: type 1 was defined as those directly passing through a defect of the mylohyoid muscle with the presence (type 1A) or absence (type 1B) of the tail sign and type 2 as those through the traditional posterior route along the free edge of the mylohyoid muscle. Images were also analyzed for the extent of the lesion in respect to the spaces involved. As for type 1 lesions, we recorded the location of the defect of the mylohyoid muscle and the position of the sublingual gland in relation to the defect.
  
  
  RESULTS
  CT scans demonstrated type 1 lesion in 36 (88%), including type 1A in 14 and type 1B in 22, and type 2 lesion in 5 (12%). Irrespective of the type, the submandibular space was seen to be involved in all cases either alone or in combination with one or more adjacent spaces. Of the 36 patients with type 1 lesions, the anterior one-third was the most common location of the defect of the mylohyoid muscle, seen in 22 patients. The sublingual gland partially herniated in 30 patients.
  
  
  CONCLUSIONS
  Our results suggest that the majority of plunging ranulas take an anterior shortcut through a defect of the mylohyoid muscle.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.; Department of Radiology, Hanyang University Hospital, Hanyang University College of Medicine, Seoul 04763, Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Hyung-Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Departments of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Han Sin
authors.initials: HS
authors.lastname: Jeong
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Yi-Kyung
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Cha
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
authors.forename: Sung Tae
authors.initials: ST
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009334:Neck Muscles / Q000000981:diagnostic imaging / Q000473:pathology; D011900:Ranula / Q000000981:diagnostic imaging* / Q000473:pathology; D012189:Retrospective Studies; D013361:Sublingual Gland / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Anatomy; CT; Plunging ranula; Salivary glands