title: Spontaneous rhabdomyosarcoma in a young Sprague-Dawley rat.
abstract: An eight-week-old male Sprague-Dawley (SD) rat showed signs of emaciation, and masses were found in the subcutis around the cervical and thoracic regions. At necropsy, a multilobular mass, 2.2 x 1.8 x 2.0 cm in size, had grown from the left neck into the thoracic cavity. On a cutting surface, masses were firm and whitish to tan, with necrotic and hemorrhagic plaques. Microscopically, masses were composed of multiple nodules of tumor cells that were incompletely encapsulated with fibrous connective tissue. The tumor cells exhibited varied forms, from spindle to globoid shapes with minimal to abundant eosinophilic cytoplasm, and appeared as large, multinucleated cells; many of the tumor cells were vacuolated. Histochemistry results revealed that tumor cells exhibited some cross-striation in the cytoplasm using PTAH staining. There were some multinuclear tumor cells with vacuoles located around the nuclei, and these vacuoles showed reddish staining by the periodic acid Schiff (PAS) method. Immunohistochemical staining also expressed intense granular cytoplasmic staining for desmin and myoglobin, with highly positive staining for PCNA, whereas alpha-smooth muscle actin (alpha-SMA) was negative. Based on the pathology results, a spontaneous rhabdomyosarcoma with pleomorphic type was diagnosed in a young SD rat.
authors.affiliation: Department of Veterinary Medicine and Veterinary Medical Teaching Hospital, National Chung-Hsing University, Taichung, Taiwan, ROC.
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Chang
authors.forename: Kosei
authors.initials: K
authors.lastname: Inui
authors.forename: Wei-Cheng
authors.initials: WC
authors.lastname: Lee
authors.forename: Shih-Ling
authors.initials: SL
authors.lastname: Hsuan
authors.forename: Maw-Sheng
authors.initials: MS
authors.lastname: Chien
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Chen
authors.forename: Shi-Jan
authors.initials: SJ
authors.lastname: Chang
authors.forename: Jiunn-Wang
authors.initials: JW
authors.lastname: Liao
mesh_terms: D000199:Actins / Q000032:analysis; D000208:Acute Disease; D000818:Animals; D003937:Diagnosis, Differential; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D006416:Hematoxylin; D006651:Histocytochemistry; D007150:Immunohistochemistry; D008297:Male; D010503:Periodic Acid-Schiff Reaction; D010772:Phosphotungstic Acid; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012208:Rhabdomyosarcoma / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D012376:Rodent Diseases / Q000175:diagnosis / Q000473:pathology*; D013194:Staining and Labeling; D013899:Thoracic Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*
chemical_list: D000199:Actins; D006416:Hematoxylin; D010772:Phosphotungstic Acid; D018809:Proliferating Cell Nuclear Antigen; C498862:Acta2 protein, rat