Poorly differentiated leiomyosarcoma of the urogenital tract in a horse.
METHODS
A 2-year-old Thoroughbred filly was evaluated because of hemorrhage from the vulva and suspected hematuria of 5 days' duration.


RESULTS
A primary coagulopathy was ruled out on the basis of results of hematologic testing. Vaginoscopy and cystoscopy revealed a large bleeding mass in the bladder that extended into the vagina, causing marked obliteration of normal urogenital structures and difficulty in urination. Histologic examination of endoscopic and surgical biopsy specimens revealed a poorly differentiated neoplasia likely of mesenchymal origin. Chronic suppurative cystitis caused by Streptococcus zooepidemicus was also diagnosed.


RESULTS
The tumor continued to grow despite treatment with doxorubicin and, within 45 days, was causing substantial discomfort and stranguria. Given the grave prognosis, the horse was euthanized. At necropsy, the tumor was found to have caused widespread destruction of the urinary bladder and to have invaded the broad ligament of the uterus. The mass was identified as a poorly differentiated leiomyosarcoma on the basis of results of histologic examination and immunohistochemical staining for alpha-actin.


CONCLUSIONS
Findings suggested that leiomyosarcoma should be considered in the differential diagnosis when examining horses with urogenital bleeding.
Hurcombe
Samuel D A
SD
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
Slovis
Nathan M
NM
Kohn
Catherine W
CW
Oglesbee
Michael
M
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D004317:Doxorubicin / Q000627:therapeutic use; D017809:Fatal Outcome; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D007890:Leiomyosarcoma / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*; D014594:Uterine Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*
D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin