THE GRADING, DIAGNOSIS AND PROGNOSIS OF CANINE MAST CELL TUMORS

Abstract

Forty-seven cutaneous mast cell tumors from dogs were pathologically classified into three
grades numbered grade 1 to 3. Age, sex, breed, tumor location, and their histologic grading were tabulated. Luna’s method, Unna’s method, Giemsa, toluidine blue, and alcian blue/safranine stainings were applied in order to compare the diagnosis and prognosis of the tumors. The staining was positive for mast cell tumors by the different methods 64% (30/47), 68% (32/47), 70% (33/47), 72% (34/47), and 81% (38/47), respectively. The accuracy of the staining decreased when the mast
cells became poorly differentiated. The alcian blue/safranine stain yielded the greatest number of positives: 70% (7/10) for grade I (well differentiated) tumors, 85% (29/34) for grade II (moderately differentiated) tumors, and 67% (2/3) for grade III (poorly differentiated) tumors. However, these results did not difference significantly from the others (p> 0.05). The study suggested that alcian blue/safranine staining should be considered as a suitable staining method for the grading and diagnosis of canine mast cell tumors. Argyrophilic, nucleolar, organizer regions, histochemical staining (AgNORs) and immunohistochemical staining for anti-proliferating cell nuclear antigens (PCNA) were also evaluated. The mean standard deviation (SD) of AgNORs and PCNA for the three grades were 1.54±0.42, 2.14±0.53, and 2.33±0.72 and 15±16.9, 251±354.0, and 215±114.1, respectively. The means of AgNORs and PCNA for grade I tumor were significantly different from those of grade II and III tumors (p< 0.05), but no differences were seen between those of grade II and grade III. An increase in the numbers of AgNORs and PCNA-positive cells correlated with the malignancy of the canine mast cell tumors. The study indicated that AgNORs and PCNA staining can be used to provide a prognosis for canine mast cell tumors cases.