title: Intramuscular keratocyst as a soft tissue counterpart of keratocystic odontogenic tumor: differential diagnosis by immunohistochemistry.
abstract: Keratocystic odontogenic tumor (KCOT), a developmental jaw cyst previously referred to as odontogenic keratocyst (OKC), typically arises in the jawbone. In this article, however, we report a case of KCOT located within the temporalis muscle. We compared its immunohistochemical profiles with those of authentic jaw KCOT, orthokeratinized odontogenic cyst, and epidermoid cyst in order to consider whether a soft tissue counterpart of KCOT could be a separate disease entity. The patient was a 46-year-old man with a well-defined cystic lesion within the left temporalis muscle. On computed tomographic images, the lesion was recognized as a cystic lesion, although KCOT was not included in the clinical differential diagnoses. The location of the lesion was not within bone but, rather, within the temporalis muscle that was attached to the jawbones. Our review of the literature has disclosed more than 20 peripheral KCOT cases of the oral mucosa and more than 10 cases of the skin, but only 1 case arising in muscle. Immunohistochemical investigation of the present intramuscular case reveals KCOT-characteristic profiles distinct from the other 3 types of cysts investigated. The results indicate that KCOT-like lesions can arise within soft tissues, although use of the term odontogenic might seem inappropriate in those cases.
authors.affiliation: Oral Pathology Section, Department of Surgical Pathology, Niigata University Hospital, Niigata 951-8520, Japan; Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Abé
authors.forename: Satoshi
authors.initials: S
authors.lastname: Maruyama
authors.forename: Manabu
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Ahmed
authors.initials: A
authors.lastname: Essa
authors.forename: Hamzah
authors.initials: H
authors.lastname: Babkair
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Mikami
authors.forename: Susumu
authors.initials: S
authors.lastname: Shingaki
authors.forename: Tadaharu
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.forename: Takashi
authors.initials: T
authors.lastname: Saku
mesh_terms: D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D007573:Jaw Neoplasms / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D009807:Odontogenic Cysts / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D013703:Temporal Muscle / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed
keywords: Cutaneous keratocyst; Intramuscular KCOT; Keratocyst; Keratocystic odontogenic tumor (KCOT); Peripheral KCOT