• Journal of Veterinary Clinics
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• v.30 no.6
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• pp.486-489
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• 2013

An 18-year-old, neutered female, Yorkshire terrier was presented with abdominal mass. Large abdominal mass was located in right 4th and 5th mammary glands. Surgically excised mammary mass was submitted for histological evaluation. Microscopically, multifocal to confluent neoplastic foci were existed from superficial dermis to subcutis. Several different growth patterns such as comedo, solid, cribriform, and micropapillary were present in the neoplastic foci. Large neoplastic mammary ducts showed great invasive tendency to adjacent tissues. Many superficial lymphatic plexuses and dermal lymphatics contained numerous neoplastic cell emboli. Because comedo pattern was demonstrated by more than 50% of the neoplastic cell population, we confirmed this case as mammary comedocarcinoma according to recent classification of canine mammary tumors.