DR: Skin tumours

Question 1

How do you diagnose skin neoplasia?

Answer 1

• hx
• CE (differentiate suspicious from likely benign. Focus on lesion, drainage LN and other abnormalities)
• FNA (core or aspiration) - to differentiate neoplasm from proliferative and ulcerative skin conditions
• Excisional biopsy to ID lesion, grade and margins
• Incisional biopsy
• IHC to differentiate tumour types
• chest radiography; should always include at least 2 inflated views of all lung fields to ensure no abnormalities were missed.

Question 2

What are the 3 main categories of cell type that give rise to neoplasia in the skin? Example of each?

Answer 2

• ROUND cell - MCT
• EPITHELIAL cell - adenoma
• SPINDLE cell - fibroma

Question 3

Why is it important to know the cell type (round, epithelial, spindle) of a tumour?

Answer 3

often tumours of a particular cell type behave in a similar manner.

Question 4

What might indicate malignancy?

Answer 4

nuclear changes and atypia (more likely to reflect malignancy than cytoplasmic changes) e.g large or multiple cell nucleoli, pleomorphism, anisokaryosis and multinucleation

Question 5

What is a histological difference between MCTs in dogs and cats?

Answer 5

CATS - poorly staining intracytoplasmic granules

DOGS - good staining of intracytoplasmic granules

Question 6

Which tumour is most commonly seen in young animals and how would you treat it?

Answer 6

HISTIOCYTOMAS (young dogs)

Question 7

How do MCTs differ between dogs and cats?

Answer 7

DOGS - Common sites of metastases (dog) – liver, spleen. Usually malignant

• Location: trunk limbs, between toes
• Breeds: Boxers, Boston terriers, English bulldogs, bull terriers, fox terriers, labs, weimeranas
• Tx
• Prognosis: poorer than cat (especially on mm, around mouth or internal organs, in blood, in BM or ulcerated)
• Good staining of intracytoplasmic granules (histology or cytology)

CATS
– Location: commonly seen on head and neck,
– Breed: Siamese
– Age: usually middle age or older (4+)
– Malignancy: frequently benign
– Tx – removal of entire tumour with surgery, usually one surgery curative, sometimes surgery not needed as MCT resolves on its own.
– Prognosis: better in cats than dogs
– poorly staining intracytoplasmic granules on histopathological or cytological examination.

Question 8

Tx - histiocytomas

Answer 8

consider benign, most resolve within 2-3 months without treatment. Surgical excision is optional once diagnosed.