MAST CELL TUMOURS OF THE DOG

Max Doig

9y1m, MN, Labrador Mass first noticed 25th June 2014 Referred last week after diagnosis of MCT

on the left proximal hindlimb (FNA and cytology)

Admitted to the SAH for staging/surgical assessment of mass.

Max also had other lumps that had been diagnosed as lipomas and one suspicious lump in the submandibular region.

Other than multiple masses Max was normal on physical exam.

Whilst admitted:

Haematology and Biochemistry Tumour mapped Chest xrays Abdominal ultrasound + Aspiration of

spleen

Repeat FNA for submandibular lump

General Presentation/clinical signs

Very common Account for 20% of all skin tumours in

dogs Commonly affects middle aged to older

dogs May demonstrate rapid growth Solitary or multiple sites Varied appearance May arise from any skin site on the body Size may alter relatively quickly Gastrointestinal effects (including possible

PNS)

Examples of MCTs

Changes in size

Granules contain: - histamine - heparin - vasoactive amines

Degranulation may occur leading to their release

Local effects

Systemic effects (hyperhistaminaemia – PNS)

Diagnosis

FNA Biopsy- excisional vs incisional

Staging• Regional LN aspiration (if appropriate)• Chest xrays• Abdominal ultrasound• Other tests prior to treatment:

- Haematology/biochemistry- Urinalysis

A modified World Health Organization TNM classification of canine mast cell tumors

Stage Description: 0: One tumour incompletely excised from the

dermis, without regional lymph node involvement

I: One tumour confined to the dermis, without regional lymph node involvement

II: One tumour confined to the dermis, with regional lymph node involvement

III: Multiple dermal tumours or large infiltrating tumour, with or without regional lymph node involvement

IV: Any tumour with distant metastasis or recurrence with metastasis

Grading systems Patnaik (graded 1-3 below) vs Kiupel (low

or high grade)

Treatment

Aim: complete resection• Low grade (1,2)- wide local excision (or radiotherapy in some cases) - Cytoreductive surgery + radiotherapy- Cytoreductive surgery + chemotherapy

• High grade (3)- Wide local excision + chemotherapy (+/- radiotherapy)

Back to Max

Max’s owners decided on surgical excision He is booked in Tuesday 29nd Julyo Marginal resection has been selected by the

owners

Max’s owners decided early on that they did not wish max to receive chemotherapy.

Max was not sent home with any gastrointestinal protectants as he had not exhibited any GI signs. (Anti-histamines were suggested- H1 antagonist)

Chemotherapy

Only indicated for management of high grade malignant/metastatic tumours

Varied response Options include• Vinblastine + prednisolone • Lomustine + prednisolone• Vinblastine + lomustine • Tyrosine kinase inhibitors (Masitinib,

Toceranib)

Radiotherapy

A common protocol would be radiation mon/wed/fri for 4 weeks

May also see daily treatment mon-fri for 3.5-4 weeks

GI Protectants H2 antagonists: • eg Famotidine (0.5-1 mg/kg p.o. q12-24h.)

Omeprazole: • 0.5-1 mg/kg p.o, iv q24h (for maximum of 8weeks)

Sucralfate (if evidence of GI ulceration/bleeding)• If <20kg: 500mg/dog p.o. q6-8h• >20kg: 1-2g/dog p.o. q6-8h

H1 antagonists • eg Loratadine (5-15mg q24h)

Prognosis

Major prognostic factors:• Tumour grade• Mitotic index• Surgical margins• Tumour stage (eg LN involvement)

Minor prognostic factors:• C-kit expression pattern• Ki-67 expression

References J Vet Intern Med. 1990 Sep-Oct;4(5):242-6.Plasma histamine and gastrin concentrations in 17 dogs with mast cell tumors.Fox LE1, Rosenthal RC, Twedt DC, Dubielzig RR, MacEwen EG, Grauer GFhttp://www.ncbi.nlm.nih.gov/pubmed/2124627

Canine Mast Cell Tumorshttp://www.vetmed.wsu.edu/deptsOncology/owners/mastcell.aspx

Mast Cell Tumors http://www.veterinarycancer.com/mastcelltumors2.html

Canine and feline skin tumors (Part 2)James Warland MA VetMB MRCVS, Jane Dobson MA BVetMed DVetMed Dipl. ECVIM-CA and Onc MRCVS - 18/02/2012http://vetgrad.com/show10MinuteTopUp.php?type=&Entity=10MinuteTopUps&ID=78

References continued

Not all lumps are lipomas: Canine Mast Cell Tumours Dr Angela Frimberger VMD, MANZCVS, Diplomate ACVIM(Onc) Dr Antony Moore BVSc, MVSc, MANZCVS, Diplomate ACVIM(Onc)

http://www.ava.com.au/sites/default/files/AVA_website/pdfs/NSW_Division/SMALL%20ANIMAL%20%20Frimberger%20%26%20Moore%20%20Mast%20Cell%20Tumors%20%20Not%20all%20lumps%20are%20lipomas.pdf

Radiation therapy for canine mast cell tumors, Monique N.Mayerhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823470/pdf/16604985.pdf

Mast Cell Tumours (MCTs) http://www.caninecancer.com/Mast.html

Questions?