title: Laryngeal rhabdomyoma in a dog.
abstract: A 3-year-old, female spayed Australian Shepherd dog was presented to Veterinary Healthcare Associates in Winter Haven, FL with a history of respiratory stridor, difficulty swallowing, and a change in bark for approximately 3 months. Radiographs revealed a soft tissue mass caudal to the epiglottis. Oral and computerized tomographic (CT) examinations were performed under general anesthesia and revealed a small firm mass in the caudal larynx on the right side. Cytologic evaluation of a fine-needle aspirate of the mass revealed cells consistent with a rhabdomyoma, oncocytoma, or granular cell tumor. Histopathologic interpretation was rhabdomyoma or oncocytoma. Histochemical staining with periodic acid-Schiff was mostly negative with a low number of weakly positive cells and with phosphotungstic acid-hematoxylin was strongly positive with visible cross striations. Tumor cells did not express pancytokeratin AE1/AE3, were strongly immunoreactive for myoglobin and muscle-specific actin, and did not express vimentin except for a low number of weakly immunoreactive cells. These findings confirmed a diagnosis of rhabdomyoma. Primary neoplasia of the larynx is rare, and widely varying types of neoplasms have been documented in this location. Due to the cytologic and histologic similarities between rhabdomyoma, oncocytoma, and granular cell tumor, these neoplasms should be differentiated using histochemical staining and immunohistochemical analysis.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA. mdunbar@ufl.edu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Dunbar
authors.forename: Pamela
authors.initials: P
authors.lastname: Ginn
authors.forename: Matthew
authors.initials: M
authors.lastname: Winter
authors.forename: Karri Barabas
authors.initials: KB
authors.lastname: Miller
authors.forename: William
authors.initials: W
authors.lastname: Craft
mesh_terms: D000199:Actins / Q000378:metabolism; D018249:Adenoma, Oxyphilic / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D000818:Animals; D044963:Biopsy, Fine-Needle / Q000662:veterinary; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D005260:Female; D016586:Granular Cell Tumor / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D007822:Laryngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D007830:Larynx / Q000000981:diagnostic imaging / Q000473:pathology; D009211:Myoglobin / Q000378:metabolism; D009928:Organ Specificity; D012207:Rhabdomyoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D014057:Tomography, X-Ray Computed / Q000662:veterinary
chemical_list: D000199:Actins; D009211:Myoglobin