Use of a 2-tier histologic grading system for canine cutaneous mast cell tumors on cytology specimens

作者：Hergt Franziska^*; von Bomhard Wolf; Kent Michael S; Hirschberger Johannes

来源：Veterinary Clinical Pathology, 2016, 45(3): 477-483.

DOI：10.1111/vcp.12387

• Cytomorphologic criteria
• dog
• fine-needle aspirates
• nuclear abnormalities

Background: Mast cell tumors (MCT) represent the most common malignant skin tumor in the dog. Diagnosis of an MCT can be achieved through cytologic examination of a fine-needle aspirate. However, the grade of the tumor is an important prognostic marker and currently requires histologic assessment. Recently a 2-tier histologic grading system based on nuclear features including number of mitoses, multinucleated cells, bizarre nuclei, and karyomegaly was proposed.
Objectives: The aim of this study was to assess if the cytomorphologic criteria proposed in the 2-tier histologic grading system are applicable to cytology specimens.
Methods: A total of 141 MCT specimens reported as grade I, II, or III according to the Patnaik system with both histologic specimens and fine-needle aspirates available were histologically and cytologically reevaluated in a retrospective study.
Results: According to the 2-tier grading system, 38 cases were diagnosed histologically as high-grade and 103 as low-grade MCT. Cytologic grading resulted in 36 high-grade and 105 low-grade tumors. Agreement between histologic and cytologic grading based on the 2-tier grading system was achieved in 133 cases (sensitivity 86.8%, specificity 97.1%, kappa value 0.853), but 5 high-grade tumors on histology were classified as low-grade on cytology.
Conclusion: Cytologic grading of MCT in the dog is helpful for initial assessment. However, the reliability of cytology using the 2-tier grading system is considered inadequate at this point. Prospective studies including clinical outcome should be pursued to further determine diagnostic accuracy of cytologic mast cell grading.

• 出版日期2016-9