Mastocytoma is a tumor that arises from mast cells, which are part of the immune system. It is one of the most common skin tumors in dogs and is less common in cats. Prognosis and treatment strongly depend on the type, location and degree of malignancy of the tumor.

Mastocytoma in dogs

Characteristics:

• The most common skin tumor in dogs.
• It can be single or multiple.
• It has a wide range of malignancy - from benign to aggressive metastatic forms.
• It is more common in the following breeds: boxer, bulldog, labrador, and sharpei.

Classification:
1. Histologic grading (Patnaik or Kiupel):

• Patnaik:

- Grade I - benign.
- Grade II - intermediate.
- Grade III - malignant, aggressive.

• Kiupel:

- Low-grade (low grade).
- High-grade (high grade, worse prognosis).

2. Staging:

• It is carried out with the help of ultrasound, X-ray, lymph node biopsy, blood tests, fine needle aspiration.

Treatment:

• Surgical excision is the method of choice for solitary tumors with sufficient margins from the tumor edge (3-5 cm).
• Chemotherapy/targeted therapy is used for aggressive or inoperable tumors.
• Radiation therapy is used for large tumors that cannot be completely removed.
• Steroids - may temporarily shrink the tumor.

Prognosis:

• Depending on stage location and malignancy, 1-5 years

Mastocytoma in cats

Characteristics:

• Less common than in dogs.
• There are cutaneous and visceral (internal) forms.
• The Siamese breed has a predisposition to benign cutaneous forms.

Types:

1. Cutaneous form:

• Often benign.
• It looks like a nodule, sometimes multiple.
• Surgical removal is usually sufficient.

2. Visceral (splenic, intestinal):

• The more aggressive form.

Treatment:

• Cutaneous form: surgical removal.
• Visceral: surgery and chemotherapy

Prognosis:

• Cutaneous form: good 1-5 years
• Visceral: depends on the extent of the lesion, but usually cautious 1-12 months.