title: Benign notochordal cell tumors: A comparative histological study of benign notochordal cell tumors, classic chordomas, and notochordal vestiges of fetal intervertebral discs.
abstract: Intraosseous benign notochordal cell tumors are recently recognized conditions that may undergo malignant transformation to classic chordomas. This study attempts to define the morphologic and immunohistochemical characteristics of 34 benign notochordal cell tumors by contrasting them with classic chordomas and the notochordal vestiges in fetal intervertebral discs. Benign notochordal cell tumors were characterized by well-demarcated though unencapsulated sheets of adipocyte-like vacuolated and less vacuolated eosinophilic cells within axial bones. The round nuclei were mildly polymorphic but bland. The tumor cells often contained cytoplasmic eosinophilic hyaline globules and lack any intercellular myxoid matrix or necrosis. The involved bone trabeculae were often sclerotic without evidence of bone destruction. The histologic features were different from those of both notochordal vestiges in fetal intervertebral discs and classic chordomas. There was overlap in immunohistochemical reactivity of benign notochordal cell tumors and chordomas, but notochordal vestiges failed to demonstrate cytokeratin 18 positivity. A more appropriate term for the lesions is "benign notochordal cell tumor" rather than "notochordal rest" or "notochordal hamartoma" as they are not rests and do not fulfill the definition of hamartoma. Benign notochordal cell tumors do not need any surgical procedure and must be adequately recognized to prevent unnecessary operations.
authors.affiliation: Department of Pathology, Koshigaya Hospital, Dokkyo University School of Medicine, Saitama, Japan. takehiko@dokkyomed.ac.jp
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Suzuki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ishiiwa
authors.forename: Ken
authors.initials: K
authors.lastname: Shimizu
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Ueda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000473:pathology*; D002817:Chordoma / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000196:embryology*; D007633:Keratins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009672:Notochord
chemical_list: D007633:Keratins