title: Undifferentiated (embryonal) sarcoma of the liver in middle-aged adults: smooth muscle differentiation determined by immunohistochemistry and electron microscopy.
abstract: Undifferentiated (embryonal) sarcoma of the liver (UESL) is a rare pediatric liver malignancy that is extremely uncommon in middle-aged individuals. We studied 2 cases of UESL in middle-aged adults (1 case in a 49-year-old woman and the other in a 62-year-old man) by histology, immunohistochemistry, and electron microscopy to clarify the cellular characteristics of this peculiar tumor. One tumor showed a mixture of spindle cells, polygonal cells, and multinucleated giant cells within a myxoid matrix and also revealed focal areas of a storiform pattern in a metastatic lesion. The other tumor was composed mainly of anaplastic large cells admixed with few fibrous or spindle-shaped components and many multinucleated giant cells. In both cases, some tumor cells contained eosinophilic hyaline globules that were diastase resistant and periodic acid-Schiff positive. Immunohistochemically, the tumor cells showed positive staining for smooth muscle markers, such as desmin, alpha-smooth muscle actin, and muscle-specific actin, and also for histiocytic markers, such as alpha-1-antitrypsin, alpha-1-antichymotrypsin, and CD68. Electron microscope examination revealed thin myofilaments with focal densities and intermediate filaments in the cytoplasm of tumor cells. Our studies suggest that UESL exhibits at least a partial smooth muscle phenotype in middle-aged adults, and this specific differentiation may be more common in this age group than in children. Tumor cells of UESL with smooth muscle differentiation in middle-aged adults show phenotypic diversity comparable to those of malignant fibrous histiocytoma with myofibroblastic differentiation.
authors.affiliation: Department of Pathology, School of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nishio
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
authors.forename: Naomi
authors.initials: N
authors.lastname: Sakashita
authors.forename: Seiji
authors.initials: S
authors.lastname: Haraoka
authors.forename: Teruto
authors.initials: T
authors.lastname: Isayama
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Naito
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Miyayama
authors.forename: Yuuya
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kikuchi
mesh_terms: D000199:Actins / Q000032:analysis; D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D003893:Desmin / Q000032:analysis; D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure; D005260:Female; D006056:Golgi Apparatus / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology*; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology*; D010503:Periodic Acid-Schiff Reaction; D000514:alpha 1-Antichymotrypsin / Q000032:analysis; D000515:alpha 1-Antitrypsin / Q000032:analysis; D000097382:CD68 Molecule
chemical_list: D000199:Actins; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D003893:Desmin; D000514:alpha 1-Antichymotrypsin; D000515:alpha 1-Antitrypsin; C067980:CD68 antigen, human; D000097382:CD68 Molecule