Introduction

• A large array of prognostic tests is available for canine cutaneous mast cell tumors (MCTs) Skin: mastocytoma but initially their grading is based on combining the Patnaik and Kuipel schemes to include the mitotic index.
• MCTs are traditionally split into three groups (low, intermediate and high - Patnaik) or with the newer Kuipel scheme, into low and high. These schemes are based on different features and in some ways are complementary and best considered in conjunction. Low grade are considered local and surgical disease with a good prognosis, high grade more likely metastatic or systemic and aggressive with a poor prognosis. The intermediate Patnaik group can be further assessed using the tests below to provide more detailed prognostic information.
• The tests all measure different things and no single marker will reliably differentiate benign tumors from the malignant minority within the group of Patnaik grade II MCTs.
• The prognostic markers must always be considered in conjunction with the clinical presentation, histological grade and staging - histological grade remains the single more useful prognostic test Neoplasia: TMN staging.
  Consultation with a clinical oncologist is always advisable if considering further tests and/or treatment options for these tumors.
• The tests discussed in the sections below are all performed using formalin-fixed, paraffin-embedded tissue samples, so the same sample submitted for the initial histological assessment and grading can then be subsequently used for these further tests.
• Many diagnostic laboratories will perform some or all of these tests in-house; other laboratories will send the samples to a specialist laboratory (particularly for the PCR-based tests Polyermase chain reaction).
• The application of these schemes can be variable at different labs or by different histopathologists and so along with an oncological consultation and use of more objective prognostic testing, every report should be critically assessed for each MCT.

Mitotic index

Ki67

AgNOR

Ag67

Mutations in the c-KIT gene

KIT staining pattern

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Giantin M, Vascellari M, Morello E M et al (2012) c-KIT messenger RNA and protein expression and mutations in canine cutaneous mast cell tumours: correlations with post-surgical prognosis. J Vet Diag Invest 24 (1), 116-1126 PubMed.
• Maglennon G A, Murphy S, Adams V et al (2008) Association of Ki67 index with prognosis for intermediate-grade canine cutaneous mast cell tumours. Vet Comp Oncol 6 (4), 268-274 PubMed.
• Webster J D, Yuzbasiyan-Gurkan V, Thamm D H et al (2008) Evaluation of prognostic markers for canine mast cell tumours treated with vinblastine and prednisone. BMC Vet Res 4, 32 PubMed.
• Webster J D, Yuzbasiyan-Gurkan V, Miller R A et al (2007) Cellular proliferation in canine cutaneous mast cell tumours: associations with c-KIT and its role in prognostication. Vet Pathol 44 (3), 298-308 PubMed.
• Scase T J, Edwards D, Miller J et al (2006) Canine mast cell tumours: correlation of apoptosis and proliferation markers with prognosis. J Vet Intern Med 20 (1), 151-158 PubMed.
• Kiupel M, Webster J D, Kaneene J B et al (2004) The use of KIT and tryptase expression patterns as prognostic tools for canine cutaneous mast cell tumours. Vet Pathol 41 (4), 371-377 PubMed.
• Zemke D, Yamini B & Yuzbasiyan-Gurkan V (2002) Mutations in the juxtamembrane domain of c-KIT are associated with higher grade mast cell tumours in dogs. Vet Pathol 39 (5), 529-535 PubMed.
• Abadie J J, Amardeilh M A & Delverdier M E (1999) Immunohistochemical detection of proliferating cell nuclear antigen and Ki-67 in mast cell tumours from dogs. JAVMA 215 (11), 1629-1634 PubMed.
• Simoes J P, Schoning P & Butine M (1994) Prognosis of canine mast cell tumours: a comparison of three methods. Vet Pathol 31 (6), 637-647 PubMed.
• Bostock D E, Crocker J, Harris K et al (1989) Nucleolar organizer regions as indicators of post-surgical prognosis in canine spontaneous mast cell tumours. Brit J Cancer 59 (6), 915-918 PubMed.

Other sources of information

• Warland J, Brioschi V, Owen L and Dobson J (2015) Canine mast cell tumours: decision-making and treatment. In Practice 37 , 315-332.
• Blackwood L, Murphy S, Buracco P, De Vos J P, De Fornel-Thibaud P, Hirschberger J, Kessler M, Pastor J, Ponce F, Savary-Bataille K, Argyle D J (2012) European consensus document on mast cell tumours in dogs and cats. Vet Comp Oncol 10 (3), e1 - e29 PubMed.
• http://www.vetcancersociety.org/members/files/2014/05/Consensus_CCMCT-Grading.pdf
• http://api.ning.com/files/hMNECPNor98pMPwiAayuBHh-sOuMf-6tB9sjK1jOhIAo5W00Q5wubEfLCRjkUcegYWwM*I1yaspHZ06L8oat7YNviKvRhRgm/ConsensusMCTKITckit_Final.pdf