Cytologie Differentiation of Benign from Malignant Canine Mammary Tumors

Abstract

Abstract. Cytologic and histologic examination of 91 canine mammary masses was performed by two cytologists and two histopathologists. Ten important cytologic criteria of malignancy for canine mammary tumors were identified. A cytologic grading system for differentiation of benign from malignant mammary tumors was proposed using these criteria. With this system, approximately one fourth of the malignant mammary tumors were given a concordant cytologic diagnosis. Approximately one-half of the benign masses were given a concordant cytologic diagnosis by the two cytologists. One-half of all the tumors examined were given inconclusive cytologic diagnoses by both cytologists. The cytologic identification of spindle cells did not differentiate complex and mixed mammary tumors from simple tumors. Only five of the animals studied died of mammary cancer, precluding a critical analysis of the cytologic criteria for prediction of cancer mortality.Tumors of the mammary gland are a common clinical problem in the adult bitch, comprising up to 52% of all neoplasm^.^ The frequency of malignancy among mammary tumors is approximately 50%.4~8~28 The disease is commonly multicentric, and tumors in a single dog may be of more than one type.9,25,32.36 Clinical findings identified by history or physical examination that could indicate malignancy include a tumor diameter of greater than 5 cm, recent rapid growth, infiltration of surrounding tissues, erythema, and edema.3,4,34 Most canine mammary tumors (Le., benign and malignant) exhibit none of these findings. Other prognostic indicators (i.e., cellular differentiation and invasion of surrounding stroma) are identifiable only through histologic examination. Since the most common treatment for canine mammary neoplasia is surgical excision, definitive therapy often is pursued prior to diagnosis of the disease.The safety of fine needle aspiration cytology as a preoperative diagnostic test of breast cancer in women has been e s t a b l i~h e d .~,~~ It has been shown to be highly accurate (false positive rate less than 1%) in studies comparing cytologic with subsequent histologic findings.11,20,43,44 In a comparable study in the dog, 19 mammary tumors were examined cytologically and histologically. Eight out of 17 mammary carcinomas were given a concordant cytologic diagnosis, and two adenomas were diagnosed cytologically as carcinoma. l5

Estudo retrospectivo de exames citológicos realizados em um Hospital Veterinário Escola em um período de cinco anos

“…Estes podem ser justificados, pois tumores de origem mesenquimal, sólidos e complexos e mistos, possuem baixa capacidade esfoliativa, e processos císticos podem conter poucas células, inviabilizando a análise citopatológica adequada (Allen, 1986).…”

Multiple mammary tumours in a bitch: analysis of mitotic index, AgNOR count and c-erbB2 expression status: a case report

“…Grossly they vary from well-circumscribed nodules with stationary growth to large and sometimes ulcerated nodules, which grow rapidly and become fixed to adjacent tissues. The initial diagnosis of CMTs is based on clinical signs and symptoms and while fine-needle aspiration may be useful (Hellmen and Lindgren, 1989), histology is necessary for an accurate diagnosis (Allen et al, 1986). Malignant canine mammary tumours are more frequent than benign ones (Brodey et al, 1983;Shekhar et al, 2001;Reddy et al, 2009).…”

Fine Needle Aspiration Cytology (FNAC) of Neoplasms in Dogs and Cats, with Emphasis on Differential Diagnosis - A Retrospective Study

“…In the case diagnosed in this study, the radiological examination also revealed lung metastases, as frequently cited by other authors. Although in this study we diagnosed one case of malignant mammary neoplasia, according to data from the literature, mammary neoplasia remains one of the most common clinical problems of adult female dogs, representing 50-70% of the diagnosed neoplasms in dogs (Allen et al, 1986;Murakami et al, 2000).…”