Value, Limitations, and Recommendations for Grading of Canine Cutaneous Mast Cell Tumors: A Consensus of the Oncology-Pathology Working Group

Abstract

One of the primary objectives of the Oncology Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects and provide guidelines for oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup’s particular focus. In this article, the authors provide a critical review of the current literature for grading of canine cutaneous mast cell tumors, suggest guidelines for reporting, and provide recommendations for its clinical interpretation. The article mainly focuses on histologic grading, but relevant information on mitotic count and cytological grading are also discussed. This document represents the opinions of the working group and the authors but does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.

Diagnosis, Prognosis and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors

“…This consensus guideline proposes the use of both the classification systems suggested by Patnaik et al [ 48 ] and by Kiupel et al [ 80 ], for a better classification of the disease (e.g., “MCT grade 3 according to Patnaik and high-grade according to Kiupel”). The recommendation is in line with the recommendation of the American College of Veterinary Pathologists and the Veterinary Cancer Society [ 54 ].…”

“…They concluded that all techniques were adequate in differentiating between low-grade and high-grade MCTs. Some grade 2/high-grade cases may be underestimated in pre-operative biopsies, and are, thus, not recommended as the only source of therapeutic guidance and tumor staging [ 54 ].…”

“…However, although O’Connell and Thompson [ 53 ] suggested that the presence of multiple MCTs does not influence overall survival, Kiupel et al [ 19 ] have described that these cases have worse prognosis. Some cases may prove even more challenging because they have low histopathological grades, but are nevertheless associated with aggressive behavior, with regional or distant metastases already present at the time of diagnosis [ 54 ]. In contrast, some high-grade MCTs have less aggressive behavior and a favorable prognosis [ 55 ].…”

Τhe Effect of Opioid Administration on Cytologic and Histopathologic Diagnosis of Canine Cutaneous Mast Cell Tumors Treated by Surgical Excision

“…Mast cell tumors (MCTs) are the most common and frequently diagnosed malignant skin tumors in dogs, accounting for 7 to 21% of all skin neoplasms [ 1 , 2 , 3 ]. The clinical presentation, gross appearance, and biological behavior of canine cutaneous MCTs varies widely [ 4 ].…”

Evaluation of Tumor Grade and Proliferation Indices before and after Short-Course Anti-Inflammatory Prednisone Therapy in Canine Cutaneous Mast Cell Tumors: A Pilot Study

“…Mast cell tumors (MCTs) are the most common skin tumor affecting dogs, and the tumor grade is the most consistent and clinically relevant prognostic factor [1][2][3][4]. There are two MCT grading systems: the Patnaik system and the Kiupel system [3].…”