title: A peripheral primitive neuroectodermal tumor with generalized bone metastases in a puppy.
abstract: A peripheral primitive neuroectodermal tumor (pPNET), most consistent with a human Ewing's sarcoma, is described in a 5-month-old male Australian Shepherd puppy. The first tumor site detected was in the left frontal bone of the skull with apparent subsequent rapid metastases to multiple sites in the axial and appendicular skeleton and bone marrow, kidneys, and perihyphophyseal meninges. Radiographically, all bone lesions were lytic and there was also a humeral bone fracture. Histologically, the tumor was diagnosed as a small round blue cell tumor. At this stage, the differential diagnosis included a lymphoma, rhabdomyosarcoma, and a PNET of the peripheral nervous system. However, the cells had positive expression of triple neurofilament antigens as detected immunocytochemically. The cells were negative for a broad panel of canine-specific leucocyte cell marker antigens for desmin, smooth muscle actin, synaptophysin, and CD99. Ultrastructurally, the cells contained occasional dense core neurosecretory granules and intermediate filaments with intercellular desmosomal-like junctions and abundant glycogen clusters. Based on the age of the dog, the clinical history, the distribution of gross lesions, histologic characteristics of a small round blue cell tumor, and immunocytochemical and ultrastructural evidence of neuroectodermal differentiation, a diagnosis of a pPNET similar to a human Ewing's sarcoma was made.
authors.affiliation: Department of Pathology, Microbiology and Immunology, One Shields Avenue, Davis, CA 95616, USA. hedecock@ucdavis.edu
authors.forename: H E V
authors.initials: HE
authors.lastname: De Cock
authors.forename: M D M
authors.initials: MD
authors.lastname: Busch
authors.forename: M M
authors.initials: MM
authors.lastname: Fry
authors.forename: M
authors.initials: M
authors.lastname: Mehl
authors.forename: A W
authors.initials: AW
authors.lastname: Bollen
authors.forename: R J
authors.initials: RJ
authors.lastname: Higgins
mesh_terms: D000818:Animals; D019046:Bone Marrow Neoplasms / Q000556:secondary / Q000662:veterinary; D001859:Bone Neoplasms / Q000556:secondary* / Q000662:veterinary*; D003896:Desmosomes / Q000648:ultrastructure; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D006003:Glycogen / Q000648:ultrastructure; D007150:Immunohistochemistry / Q000662:veterinary; D007382:Intermediate Filaments / Q000648:ultrastructure; D007680:Kidney Neoplasms / Q000556:secondary / Q000662:veterinary; D008297:Male; D008577:Meningeal Neoplasms / Q000556:secondary / Q000662:veterinary; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000556:secondary* / Q000662:veterinary*; D016900:Neurofilament Proteins / Q000032:analysis
chemical_list: D016900:Neurofilament Proteins; D006003:Glycogen