title: Occult osseous metastasis of a colonic adenocarcinoma visualized with technetium tc 99m hydroxymethylene diphosphate scintigraphy in a horse.
abstract: A 5-year-old Arabian horse was admitted with a 5-day history of undulant pyrexia of unknown origin, inappetence, obtundation, and acute collapse. Physical examination results were unremarkable except for a grade II/VI left-sided systolic cardiac murmur and abdominal splinting. Mild chronic inflammatory changes were evident on clinicopathologic evaluation. Echocardiography revealed moderate aortic insufficiency. A solitary soft tissue opacity was found on thoracic radiography but not on ultrasonography. Palliative treatment was ineffective. Nuclear scintigraphy with WBC labeled with technetium Tc 99m hexamethylpropyleneamine oxime did not identify abnormalities, but a second nuclear scan with technetium Tc 99m hydroxymethylene diphosphate identified polyostotic disease. Examination of a biopsy specimen from an affected rib revealed disseminated adenocarcinoma. The horse was euthanatized. Necropsy and histologic examination revealed a colonic adenocarcinoma with osseous metaplasia that had disseminated to multiple parenchymal organs, muscle, and bone.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: East
authors.forename: P F
authors.initials: PF
authors.lastname: Steyn
authors.forename: C E
authors.initials: CE
authors.lastname: Dickinson
authors.forename: A A
authors.initials: AA
authors.lastname: Frank
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000556:secondary / Q000662:veterinary*; D000818:Animals; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000662:veterinary*; D003110:Colonic Neoplasms / Q000473:pathology / Q000662:veterinary*; D003937:Diagnosis, Differential; D006734:Horse Diseases / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D006736:Horses; D008297:Male; D010166:Palliative Care; D011877:Radionuclide Imaging; D019690:Technetium Tc 99m Exametazime; D013669:Technetium Tc 99m Medronate / Q000031:analogs & derivatives
chemical_list: D019690:Technetium Tc 99m Exametazime; C024226:technetium Tc 99m hydroxymethylene diphosphonate; D013669:Technetium Tc 99m Medronate