Non-inflammatory cutaneous masses Flashcards
What derm neoplasia occurs in younger dogs?
histiocytoma
Waht breeds are predisosed to mast cell tumours?
Boxers (often benign) and Golden Retrievers
What sex of dog is more likely to have hepatoid (perianal) adenomas?
male
Are dog skin tumours often benign or malignant?
What about cats?
Dogs: Most benign (approx 2/3)
Cats: Most malignant (approx 2/3)
What are the 5 most commom canine skin tumours?
- Lipoma – most common
- Sebaceous gland tumours (6-21%)
- Mast cell tumour (11%)
- Histiocytoma (10%)
- Basal cell tumour (4-11%)
What are the 4 most common feline skin tumours?
- Fibrosarcomas (25%)
- Squamous cell carcinomas (SCC) (17%)
- Basal cell tumours (15%)
- Mast cell tumours (7%)
Name 5 types of maligmant skin tumours of dogs
- Mast cell tumour (11% total)
- Squamous cell carcinoma (SCC) (1%)
- Malignant melanoma (3%)
- Soft tissue sarcomas (4%)
- Epitheliotropic lymphoma
What tumours present as multiple nodules?
- epitheliotropic/primary cutaneous lymphomas
- papillomas
- malignant tumours that metastasise to skin
- basal cell carcinoma in cats
What is the significance of is a skin tumour is superficial or deep?
- 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
when is skin biopsy and histopathology needed for tumour diagnosis?
- to confirm putative diagnosis from FNA
- where FNA is inconclusive
Why is immunohistochemistry sometimes needed before biopsy of tumours?
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
When should Lymph nodes be FNA and removed with tumours?
- Should do FNA for all enlarged LNs
- If firm node negative for neoplasia on FNA, take excisional biopsy under GA for histopathology
What is PARR testing in relation to tumours and why is it done?
= PCR for antigen-receptor rearrangement
To distinguish neoplastic from inflammatory populations, e.g. in lymphoma
What are the Principles of skin tumour excision?
- 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
What is the treatment for Sebaceous gland tumours?
- If slow-growing and well-circumscribed, may leave and monitor.
- Excise if any change or traumatised
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?
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
What is this tumour?
Basal cell tumour
What kind of tumour is this?
Sebaceous hyperplasia
What type of tumours are these?
Canine papillomas (warts)
what is the apperance of canine papilloma?
What is the management?
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
What are the charateristics of perianal (hepatoid) gland tumours?
What is the treatment?
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)
What are the two types of lipoma?
Non-infiltrating – usual form - encapsulated, soft, moveable
Infiltrating variant – uncommon
What are the characteristics of spindle cell sarcomas?
What is the treatment?
- 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
What tumour is associated with injections in cats?
‘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
Wha is the apperance and two types of mast cell tumours in dogs?
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
Paraneoplastic syndromes
What are the effects of mast cell degranulation?
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
What are the characteristics of feline MCT?
What are the three differnt types?
That is the treatment?
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
What are the two presentations of primary cutaneous lymphoma?
-
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)
-
Non-epitheliotropic lymphoma Less common than 1.
(T- or B-cell origin)
* Foci of erythroderma, crusting, ulceration
* Multiple dermal nodules/erythematous plaques
What is your top differntial for this dog?
Depigmenting mucocutaneous lesions
- Often the first sign of epitheliotropic lymphoma, before progressing to other forms
What is the prognosis of the two presentations of primary cutaneous lymphoma?
- Non-epitheliotropic lymphoma (rare) - Rapid metastasis, grave prognosis
- Epitheliotropic lymphoma - Chronic, may wax/wane initially
What should you not put on histyocytoma?
steroid cream - immunosuppresive drugs will slow regression
What are the charateristics of Canine cutaneous histiocytoma?
- 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
What tumour is this?
histiocytoma
What are the charateristics of melanomas?
what is the treatment?
- 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
What are cysts?
What are the differnt types of cutaneous cysts?
What is the risk if thye rupture?
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
What breed are associated with dermoid cysts?
where are they found?
What problems can they cause?
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!
