Clinical Exposures: Cytologic examination of a cutaneous mast cell tumor in a boxer
Mar 01, 2007
A 7-year-old intact male boxer was evaluated because of a preputial dermal mass that had been present for about one year. The mass was on the left cranial aspect of the prepuce; was nonulcerated, round, and raised; and measured about 1 x 1.5 x 1 cm. No other abnormalities were noted on physical examination. The mass was aspirated, and two unstained direct smears were prepared for cytologic evaluation.
The cytologic pleomorphism and variable granularity were suggestive of a less well differentiated and potentially more aggressive mast cell tumor. The tumor was excised with wide surgical margins, and a histologic examination confirmed a completely excised, poorly differentiated (grade III) mast cell tumor. The results of postoperative staging tests were unremarkable, and multiagent chemotherapy was initiated. Six months later, the patient was still receiving chemotherapy and was reportedly tumor-free.DISCUSSION
Cutaneous mast cell tumors are a common finding in dogs, comprising about 16% to 21% of all dermal and subcutaneous tumors.1 Breeds reportedly predisposed to mast cell tumors include boxers, Boston terriers, beagles, and Labrador retrievers. Most mast cell tumors are found in middle-aged to older dogs, but younger dogs are sometimes affected, including dogs as young as 3 weeks old.1 No gender predilection has been documented.1-3 There is wide disparity in the gross appearance of these tumors, but they classically occur as solitary dermal or subcutaneous masses. A small percentage of affected dogs may have multiple masses.1-3