Mastocytoma

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Sections available in full article Introduction, Presenting signs, Geographic incidence, Age predisposition, Breed predisposition, Special risks (e.g. anesthetic), Pathogenesis, Predisposing factors, Pathophysiology, Diagnosis, Presenting problems, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Monitoring, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Susan North BSc PhD DVM DACVIM(Onc)
Mr David Scarff BVetMed CertSAD MRCVS
Dr William Brewer Jr DVM DiplACVIM Oncology and Internal Medicine
Synonyms Mast cell tumour

Introduction

  • Less common than dog but 15% of all feline tumors.
  • Cutaneous and visceral forms.
  • Diagnosis : cytology, histopathology.
  • Treatment : surgical excision, radiotherapy, chemotherapy.
  • Prognosis : cutaneous: good; visceral: poor.

Cutaneous

  • Histological grading not prognostic unlike in dog.
  • Two forms:
    • Typical like dog and
    • Histiocytic majority are behaviorally benign.

Visceral

  • Splenic, intestinal usually malignant - associated with widespread dissemination/metastasis.
  • Often mast cell leukemia (buffy coat mastocytosis) with splenic form. Occasionally cutaneous and visceral forms occur together.

Diagnosis

Clinical signs

  • Solitary or multiple skin nodules, well-circumscribed, dome-shaped, alopecic, raised, +/- erythema, ulceration. Purple   →   Dark-red in color.
  • Suspicious mass or splenomegaly on abdominal palpation.Variations must always assess for systemic/visceral involvement, even with solitary, small dermal mass.
  • Occasional peritoneal effusion.
  • Local lymph node enlargement possible (uncommon).

Diagnosis

Differential diagnosis

  • Other skin tumors - squamous cell carcinoma  Squamous cell carcinoma  , basal cell tumor  Basal cell tumor  , fibrosarcoma lymphosarcoma  Lymphoma  .
  • Other causes of splenomegaly - lymphoma  Lymphoma  , hemangiosarcoma  Hemangiosarcoma  , myeloproliferative disease  Myeloid leukemia  .
  • Other intestinal tumors  Small intestine: neoplasia   Large intestine: neoplasia  - adenocarcinoma  Adenoma adenocarcinoma  , lymphoma  Lymphoma  .

Sequelae

Prognosis

  • Cutaneous form : good.
  • Visceral form : poor for intestinal.
  • Can be reasonable (approx 1 year) for splenic form following clinical signs of malaise, anorexia etc. despite bone marrow involvement if splenectomy has been performed (median 2 months otherwise).

Expected response to treatment

  • Removal of all visible or palpable tumor.
  • Decrease in peripheral mastocytosis.

Reasons for treatment failure

Cutaneous
  • Local recurrence or metastasis of malignant tumors to local lymph nodes or distant sites (less than 20% metastasize).
  • Previously undetected visceral or systemic involvement.

Visceral

  • Dissemination to distant sites after treatment or widespread metastasis at time of diagnosis, hence treatment not possible.

Sources

Publications

Refereed papers

  • Recent references fromPubMed.
  • Rassnick K M, Williams L E, Kristal O, Al-Sarraf R, Baez J L, Zwahlen C H, Dank G (2008)Lomustine for treatment of mast cell tumors in cats: 38 cases (1999-2005).JAVMA232(8), 1200-1205PubMed.
  • Turrel J M, Farrelly J, Page R L, McEntee M C (2006)Evaluation of strontium 90 irradiation in treatment of cutaneous mast cell tumors in cats: 35 cases (1992-2002).JAVMA228, 898-901 PubMed.
  • Wilcock B P, Yager J A & Zink M C (1986)The morphology and behavior of feline cutaneous mastocytomas.Vet Pathol23, 320-324.
  • Buerger R G & Scott D W (1986)Cutaneous mast cell neoplasia in cats - 14 cases.JAVMA190, 1440-1444.

Other sources of information

  • Carpenter J L, Andrews L K & Holzworth J (1987)Mast cell tumors.In:Diseases of the Cat., Medicine and Surgery.Ed J Holzworth. Philadelphia: W B Saunders Co. pp569-579.
  • Vail D M (1996)Feline mast cell tumors. In:Small Animal Clinical Oncology.Eds S J Withrow and E G MacEwen. 2nd edition. Philadelphia: W B Saunders Co. pp202-207.

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