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Mastocytoma
Synonym(s): tumour, MCT, cancer, neoplasia, mass
Introduction
- Less common than dog but approximately 15% of all feline tumors.
- Cutaneous and visceral forms - splenic, intestinal.
- Diagnosis: cytology, histopathology.
- Treatment: surgical excision, radiotherapy, chemotherapy.
- Prognosis: cutaneous: good; visceral: guarded.
Presenting signs
Cutaneous
- Cat is usually well.
- Mastocytic:
- Solitary, well-circumscribed, raised, alopecic dermal nodule, 0.5-3 cm diameter.
- Can be multiple (25% of cases).
- Can be pruritic, erythematous or ulcerated.
- Most common on head and neck.
- Atypical (previously called histiocytic):
- Multiple, non-pruritic, alopecic nodules. Seen in younger cats, common on head and neck.
Visceral
- Cat can be systemically unwell.
- Vomiting/diarrhea.
- Weight loss.
- Anorexia Anorexia.
- Splenic - splenomegaly Abdominal organomegaly.
- Peritoneal effusion Peritoneal: effusion.
Geographic incidence
Cutaneous
- Less common in UK than in USA.
- Atypical cutaneous form much less common than mastocytic form.
Visceral
- Common - third most common intestinal tumor after lymphoma and adenocarcinoma and most common cause of splenomegaly.
Age predisposition
- Cutaneous: mean age 8.2 years.
- Average age splenic MCTs 10 years, intestinal MCTs 13 years.
- Younger cats <4 years in Siamese Siamese breed.
Breed/Species predisposition
- Atypical: Siamese Siamese.
Special risks
- Vasoactive amine release - local inflammation, erythema and swelling or systemic release, gastric ulceration and coagulation problems.
- May get massive mediator release on handling splenic/intestinal lesions → circulatory collapse & shock Shock → death.
Pathogenesis
Predisposing factors
General
- Breed - Siamese Siamese for cutaneous form.
Pathophysiology
Cutaneous
- Most cutaneous tumors localized (mastocytic) or regress (atypical).
- Occasionally (up to 22% mastocytic) spread to lymph nodes and or internal organs.
- Multiple cutaneous tumors, may have appearance of miliary dermatitis Dermatitis: miliary (rare).
- Atypical: spontaneous regression over 4-24 months.
Visceral
- Widespread metastasis common to liver and spleen, local lymph nodes, leading to hepato-splenomegaly, depression, anorexia, vomiting, diarrhea, weight loss, intestinal obstruction, peritoneal effusion.
- Peripheral mastocytosis/anemia relatively common with splenic form.
- Coagulopathies common with splenic tumors.
- Splenomegaly may be present for a long time before clinical disease seen.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Barrett L E, Skorupski K, Brown D C, Weinstein N, Clifford C, Szivek A, Haney S, Kraiza S, Krick E L (2018) Outcome following treatment of feline gastrointestinal mast cell tumours. Vet Comp Oncol 16(2), 188-193 PubMed.
- Berger E P, Johannes C M, Post G S, Rothchild G, Shiu K B, Wetzel S, Fox L E (2018) Retrospective evaluation of toceranib phosphate (Palladia) use in cats with mast cell neoplasia. J Feline Med Surg 20(2), 95-102 PubMed.
- Sabattini S, Barzon G, Giantin M, Lopparelli R M, Dacasto M, Prata D, Bettini G (2017) Kit receptor tyrosine kinase dysregulations in feline splenic mast cell tumours. Vet Comp Oncol 15(3), 1051-1061 PubMed.
- Kraus K A, Clifford C A, Davis G J, Kiefer K M, Drobatz K J (2015) Outcome and Prognostic Indicators in Cats Undergoing Splenectomy for Splenic Mast Cell Tumors. J Am Anim Hosp Assoc 51(4), 231-238 PubMed.
- Henry C, Herrera C (2013) Mast cell tumors in cats: clinical update and possible new treatment avenues. J Feline Med Surg 15(1), 41-47 PubMed.
- Piviani M, Walton R M, Patel R T (2013) Significance of mastocytemia in cats. Vet Clin Pathol 42(1), 4-10 PubMed.
- Rassnick K M, Williams L E, Kristal O et al (2008) Lomustine for treatment of mast cell tumors in cats: 38 cases (1999-2005). JAVMA 232 (8), 1200-1205 PubMed.
- Litster A L, Sorenmo K U ( 2006) Characterisation of the signalment, clinical and survival characteristics of 41 cats with mast cell neoplasia. J Feline Med Surg 8(3), 177-183 PubMed.
- Turrel J M, Farrelly J, Page R L et al (2006) Evaluation of strontium 90 irradiation in treatment of cutaneous mast cell tumors in cats: 35 cases (1992-2002). JAVMA 228 (6), 898-901 PubMed.
- Wilcock B P, Yager J A & Zink M C (1986) The morphology and behavior of feline cutaneous mastocytomas. Vet Pathol 23 (3), 320-324 PubMed.
Other sources of information
- London C A & Thamm D H (2012) Mast cell tumors. In: Withrow S J, Vail D M & Page R L (eds). Withrow and MacEwen’s Small Animal Clinical Oncology. 5th edn. St Louis:Elsevier. pp 335-355.