- 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.
- Histological grading not prognostic unlike in dog.
- Two forms:
- Typical like dog and
- Histiocytic majority are behaviorally benign.
- 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.
- 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).
- Other skin tumors - squamous cell carcinoma , basal cell tumor , fibrosarcoma lymphosarcoma [Lymphoma] .
- Other causes of splenomegaly - lymphoma , hemangiosarcoma , myeloproliferative disease [Myeloid leukemia] .
- Other intestinal tumors [Small intestine: neoplasia] [Large intestine: neoplasia] - adenocarcinoma , lymphoma .
- 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 failureCutaneous
- Local recurrence or metastasis of malignant tumors to local lymph nodes or distant sites (less than 20% metastasize).
- Previously undetected visceral or systemic involvement.
- Dissemination to distant sites after treatment or widespread metastasis at time of diagnosis, hence treatment not possible.