title: Malignant Leydig cell tumor with spindle-shaped cells in a male CD-1 mouse.
abstract: Leydig cell tumors with spindle-shaped cells are very rare in humans and animals. We report that an 84-week-old male CD-1 mouse had a malignant Leydig cell tumor characterized by proliferation of oval to spindle-shaped cells with or without fat deposition, and with a storiform pattern. These cells were immunopositive for inhibin and S-100, and negative for the androgen receptor, thereby suggesting that they may have differentiated from Leydig cells. This differentiation from Leydig cells was further confirmed by the immunopositivity of these cells for nestin and alpha-smooth muscle actin, both of which are known to be expressed in the stem/progenitor cells that differentiate into Leydig cells. These findings suggest that the tumor is most probably a malignant spindle-cell-type Leydig cell tumor.
authors.affiliation: Laboratory of Pathology, Toxicology Division, The Institute of Environmental Toxicology, Uchimoriya-machi 4321, Joso-shi, Ibaraki303-0043, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Ohnuma
authors.forename: Toshinori
authors.initials: T
authors.lastname: Yoshida
authors.forename: Naofumi
authors.initials: N
authors.lastname: Takahashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Akema
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Kumagai
authors.forename: Yuko
authors.initials: Y
authors.lastname: Chiba
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kashimoto
authors.forename: Maki
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakashima
authors.forename: Takanori
authors.initials: T
authors.lastname: Harada
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000473:pathology; D007150:Immunohistochemistry; D007984:Leydig Cell Tumor / Q000473:pathology* / Q000662:veterinary*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012376:Rodent Diseases / Q000473:pathology; D014617:Vacuoles / Q000473:pathology