Non-inflammatory cutaneous masses

Question 1

What derm neoplasia occurs in younger dogs?

Answer 1

histiocytoma

Question 2

Waht breeds are predisosed to mast cell tumours?

Answer 2

Boxers (often benign) and Golden Retrievers

Question 3

What sex of dog is more likely to have hepatoid (perianal) adenomas?

Answer 3

male

Question 4

Are dog skin tumours often benign or malignant?
What about cats?

Answer 4

Dogs: Most benign (approx 2/3)
Cats: Most malignant (approx 2/3)

Question 5

What are the 5 most commom canine skin tumours?

Answer 5

• Lipoma – most common
• Sebaceous gland tumours (6-21%)
• Mast cell tumour (11%)
• Histiocytoma (10%)
• Basal cell tumour (4-11%)

Question 6

What are the 4 most common feline skin tumours?

Answer 6

• Fibrosarcomas (25%)
• Squamous cell carcinomas (SCC) (17%)
• Basal cell tumours (15%)
• Mast cell tumours (7%)

Question 7

Name 5 types of maligmant skin tumours of dogs

Answer 7

• Mast cell tumour (11% total)
• Squamous cell carcinoma (SCC) (1%)
• Malignant melanoma (3%)
• Soft tissue sarcomas (4%)
• Epitheliotropic lymphoma

Question 8

What tumours present as multiple nodules?

Answer 8

• epitheliotropic/primary cutaneous lymphomas
• papillomas
• malignant tumours that metastasise to skin
• basal cell carcinoma in cats

Question 9

What is the significance of is a skin tumour is superficial or deep?

Answer 9

• Epithelial tumours – usually superficial and exophytic (ie grow out from epithelial surface)
• **Mesenchymal/ round cell/ adnexal tumours **– usually intradermal or s/c, and endophytic (i.e. grow inwards)

If caught early then might be only in the epidermis and therefore easier to excise. also when penetraites the dermis then more likely to metastasize

Question 10

when is skin biopsy and histopathology needed for tumour diagnosis?

Answer 10

• to confirm putative diagnosis from FNA
• where FNA is inconclusive

Question 11

Why is immunohistochemistry sometimes needed before biopsy of tumours?

Answer 11

Labels cell-surface markers  help identify phenotype of cells in neoplasm, esp for some round cell tumours, e.g. lymphoma, MCT
NB
Highly anaplastic cells may still remain unidentifiable
Discuss value and sampling requirements with histopathologist before taking sample

Question 12

When should Lymph nodes be FNA and removed with tumours?

Answer 12

• Should do FNA for all enlarged LNs
• If firm node negative for neoplasia on FNA, take excisional biopsy under GA for histopathology

Question 13

What is PARR testing in relation to tumours and why is it done?

Answer 13

= PCR for antigen-receptor rearrangement
To distinguish neoplastic from inflammatory populations, e.g. in lymphoma

Question 14

What are the Principles of skin tumour excision?

Answer 14

• Choice of margin is paramount: wider margins needed for more infiltrative tumours
• Natural barriers to tumour spread: collagen-rich, relatively avascular structures (eg fascia, tendons, ligaments, cartilage)

Extent of surgical margin:
* Cytoreductive excision
* Marginal local excision
* ?for non-infiltrating lipomas, histiocytomas, benign sebaceous tumours
* Wide excision – most-commonly employed for skin tumours
* = removal with complete margins of normal tissue in all directions
* Radical (compartmental) excision

Question 15

What is the treatment for Sebaceous gland tumours?

Answer 15

• If slow-growing and well-circumscribed, may leave and monitor.
• Excise if any change or traumatised

Question 16

What is the apperance of basal cell tumours in cats?
what do they behave like?
What is the treatment?
What is the differnce in dogs?

Answer 16

cats:
* Solid, ulcerated or cystic
* The most common pigmented tumour in cats (d/d melanoma)
* Aggressive characteristics on cytology/histopathology but low-grade behaviour usually
* Excise with as wide a margin as possible

Dog:
* Usually benign, slow-growing.
* Wide excision to cure

Question 17

What is this tumour?

Answer 17

Basal cell tumour

Question 18

What kind of tumour is this?

Answer 18

Sebaceous hyperplasia

Question 19

What type of tumours are these?

Answer 19

Canine papillomas (warts)

Question 20

what is the apperance of canine papilloma?
What is the management?

Answer 20

Young dogs, multiple lesions
* Mouth, lips, eyes – smooth, shiny plaques or papillated lesions
* Footpads - firm, hyperkeratotic, often hornlike lesions

Caused by papilloma viruses - contagious via direct/indirect contact

Management
* Usually allow to resolve spontaneously, though new ones may develop
* Surgery if causing problems
* Topical keratolytic/softening preparations? Decreases discomfort but does not alter the course of the infection
* Imiquimod cream? Interferon? Azithromycin? Anecdotal reports

Question 21

What are the charateristics of perianal (hepatoid) gland tumours?
What is the treatment?

Answer 21

Adenomas/hyperplasia usually (benign); occasionally malignant
Usually androgen-dependent
Usually older male, but < 25% in females
In entire and neutered animals

Usually in perianal skin (occasionally tail base, dorsal lumbosacral, lateral to prepuce)
Nodules or perianal ’ring’ of lesions, +/- ulceration

Treatment
* Hormonal – surgical or chemical castration – most will regress
* If necessary, wide surgical excision (+/- prior hormonal therapy); surgery + radiotherapy if necessary

(In NM and females, consider if underlying HAC –> androgen production by hyperplastic adrenals)

Question 22

What are the two types of lipoma?

Answer 22

Non-infiltrating – usual form - encapsulated, soft, moveable
Infiltrating variant – uncommon

Question 23

What are the characteristics of spindle cell sarcomas?
What is the treatment?

Answer 23

• Solitary, slow-growing masses
• May appear well-circumscribed but actually highly infiltrative
• Low rate of metastasis
  Diagnosis on biopsy – NB poor exfoliation on FNA!! (except perivascular wall tumours)

Treatment
* Wide-radical excision, if possible, but frequently recur as incompletely excised
* Or cytoreductive surgery + radiotherapy
* Chemotherapy of little value

Question 24

What tumour is associated with injections in cats?

Answer 24

‘Injection site sarcomas’
* Association between fibrosarcomas and injection sites recognised in cats
* Usually interscapular
* If suspect, inform pharmaceutical company as suspect adverse reaction
* Consult oncologist after biopsy but before surgery

Question 25

Wha is the apperance and two types of mast cell tumours in dogs?

Answer 25

Canine MCT - shows great diversity in presentation, rate of metastasis, response to therapy – clinical challenge! Appearance * Can be cutaneous (dermal) or s/c. Occasionally extracutaneous Always a d/d for any cutaneous tumour! * Low grade – solitary slow-growing dermal nodules – often overlooked * Higher grade –may be large ill-defined soft masses (d/d lipoma, soft tissue sarcoma), +/- satellite lesions +/- ulceration Mast cell degranulation --> histamine release erythema, pruritus, oedema may fluctuate in size So d/d inflammatory masses, e.g. cellulitis, acral lick granulomas

Question 26

# Paraneoplastic syndromes What are the effects of mast cell degranulation?

Answer 26

Histamine * Local effects - +/- oedema, erythema of tumour/adjacent tissue, pruritus* * Systemic effects – +/- GI ulceration & melaena, vomiting, occasional oedema/anaphylaxis/collapse (handle suspect MCT carefully!) Heparin --> local bruising and perioperative bleeding Proteases --> poor wound healing Darier’s sign = local pruritus, erythema, wheal after rubbing lesion

Question 27

What are the characteristics of feline MCT? What are the three differnt types? That is the treatment?

Answer 27

Most commonly on skin Lesions usually solitary, well circumscribed nodules/plaques, alopecic Occasional visceral lesions (spleen, intestine)  vomiting, anorexia Diagnosis * Cytology --> mast cells * Histopathology --> divide to * **Well-differentiated mastocytic** – 60% * **Pleomorphic mastocytic** – 30% * **Atypical (histiocytic)** – 10% – classically young cats < 4yo – masses regress in time Also graded to Group 1 (benign), Group 2 (malignant) Treatment Surgery – treatment of choice for solitary masses Chemotherapy? – questionable justification unless tumour aggressive, as cats rarely die of

Question 28

What are the two presentations of primary cutaneous lymphoma?

Answer 28

1. **Epitheliotropic lymphoma** (mycosis fungoides) (usually T-cell origin) Manifestations: * Foci of erythroderma, crusting, ulceration * Multiple dermal nodules/erythematous plaques * Generalised scale, pruritus * Mucocutaneous lesions (may depigment) 2. **Non-epitheliotropic lymphoma** Less common than 1. (T- or B-cell origin) * Foci of erythroderma, crusting, ulceration * Multiple dermal nodules/erythematous plaques

Question 29

What is your top differntial for this dog?

Answer 29

Depigmenting mucocutaneous lesions - Often the first sign of **epitheliotropic lymphoma**, before progressing to other forms

Question 30

What is the prognosis of the two presentations of primary cutaneous lymphoma?

Answer 30

* Non-epitheliotropic lymphoma (rare) - Rapid metastasis, grave prognosis * Epitheliotropic lymphoma - Chronic, may wax/wane initially

Question 31

What should you not put on histyocytoma?

Answer 31

steroid cream - immunosuppresive drugs will slow regression

Question 32

What are the charateristics of Canine cutaneous histiocytoma?

Answer 32

* Common (10% skin tumours) rapidly-growing well-demarcated masses. May ulcerate * Frequently young dogs. Commonly on extremities * Increased frequency in dogs on immunosuppressive treatments * Histiocytes (round cells) on FNA – d/d MCT * Frequently resolve spontaneously

Question 33

What tumour is this?

Answer 33

histiocytoma

Question 34

What are the charateristics of melanomas? what is the treatment?

Answer 34

* well-defined deeply-pigmented flat/plaque/dome-shaped lesions in pigmented skin >85% benign --> wide excision (Malignant tumours often less well-pigmented +/- ulcerated) But * mucocutanous (e.g. eyelid, lip, oral) melanomas * digital melanomas potentially malignant with widespread metastasis Treatment: Excise with wide margins where possible Not chemosensitive New immunotherapy treatment in USA * Xenogeneic plasmid DNA vaccine (Oncept®) targeting tyrosinase * licensed for oral/mucosal melanoma

Question 35

What are cysts? What are the differnt types of cutaneous cysts? What is the risk if thye rupture?

Answer 35

Definition - epithelium-lined cavity containing fluid or solid material In skin, usually lined with adnexal epithelium: eg * Follicular cysts --> cornified debris * Apocrine cysts --> apocrine secretions * Sebaceous cysts --> sebaceous secretions * Well-circumscribed; usually solitary, sometimes multiple * Some with central pore * May observe without treatment but risk of rupture (especially at certain sites) so may elect to excise * If rupture --> inflammation +/- infection Resolve inflammation/infection before excision

Question 36

What breed are associated with dermoid cysts? where are they found? What problems can they cause?

Answer 36

Congenital defect, esp Rhodesian Ridgeback Cysts dorsal midline neck/trunk Filled with hair/keratinous material May extend to dura mater causing neurological problems excision potentially complex!