23.11.4: Cutaneous masses Flashcards
How could you decide what a cutaneous mass is?
- Signalment
- History: general, dermatological, speed of onset
- Clinical exam: general and dermatological
- Ranked ddx list
- Investigations: cytology (FNA), tissue biopsy (histopathology ± tissue culture if inflammatory)
What are the main types of skin mass (i.e. that you could differentiate on FNA)?
- Inflammatory
- Cyst
- Neoplastic
- (hyperplastic/dysplastic - less common)
What are some example causes of an infectious (septic) inflammatory cutaneous mass?
- Bacterial infection
- Fungal infection
- Protozoal infection
- Ectoparasite e.g. Demodex
True/false: FNA cytology from a neoplastic mass is likely to contain a clonal cell population.
True
Clonal population = lots of the same cells
If a cytological sample is describe as showing ‘pyogranulamtous inflammation’, what cell(s) will be present?
Neutrophils (‘pyo’) and macrophages (‘granuloma’)
* The presence of granulomatous inflammation implies a deeper infection as macrophages are not typically found at the surface.
What is a cyst and what are its content?
Cyst: epithelium lined cavity. The contents will be whatever that epithelium is making.
True/false mycobacteria can be easily identified using in-house stains.
False
Special labs will be needed to identify mycobacteria. Failure to identify them does not indicate the mass is sterile.
A mass has been identified as neoplastic on cytology. What is the next step?
Categorise the cell population as:
* Epithelial cell
* Round cell
* Mesenchymal (spindle) cell
True/false spindle cell tumours exfoliate well.
False
Spindle cell tumours do not exfoliate well.
What might mast cell degranulation result in?
Urticaria
Angiogenic oedema
If degenerated collagen is the cause of the lesion, what associated disease might we see?
Eosinophilic granuloma
Arthropod bite granuloma
If fatty acids/lipids are the cause of the lesion, what associated disease might we see?
Sterile panniculitis
Once we have classified a skin mass as inflammatory, how can we further describe it?
- Infectious (septic)
- Non-infectious (sterile)
What are some examples/causes of a non-infectious inflammatory skin mass?
- Urticaria/angioedema
- Eosinophilic granuloma
- Arthropod bite granuloma
- Sterile panniculitis
- Haematoma
- Seroma
Is this inflammation, neoplastia, or cyst?
Inflammation
Inflammation, neoplasia or cyst?
Neoplasia
Inflammation, neoplasia or cyst?
Cyst with cholesterol crystals
You have identified an inflammatory skin mass. What questions do you need to ask next?
- Predominant inflammatory cell type? i.e. neutrophilic/eosinophilic/pyogranulomatous
- Sterile vs septic? Remember not to assume sterile just because no organisms were found
What is a malignant mesenchymal cell tumour called?
sarcoma
What is a benign epithelial cell tumour called?
Papilloma
Adenoma
What is a malignant epithelial cell tumour called?
Carcinoma
Adenocarcinoma
Inflammation, neoplasia, or cyst?
Neoplasia: mesenchymal cell tumour.
Inflammation, neoplasia or cyst?
Cyst
There are squames and material in the background but not really clearly identifiable cells.
Inflammation, neoplasia or cyst?
Inflammation
Neutrophils and macrophages present
What causes urticaria and angiogenic oedema (angioedema)?
- Degranulation of mast cells or basophils
- Immunological or non-immunological causes
- Immunological: Type I or III hypersensitivites, mast cell tumours
- Non-immunological: physical forces (pressure, sunlight, heat, exercise), genetic abnormalities, drugs/chemicals (inc. food), venomous insects, plants
Treatment of urticaria
- Many cases resolve spontaneously in 12-48hrs; owners should be instructed how to monitor for anaphylaxis
- If needed, can be dexamethasone IV / prednisolone 1mg/kg q24hr for 3-5 days and taper, ± oral antihistamines
- Give adrenaline if signs of anaphylaxis
What is calcinosis cutis?
Calcinosis cutis: inappropriate deposition of calcium/phosphate in the skin/subcutis -> gritty white deposits, often with surrounding inflammation
What causes calcinosis cutis?
- Dystrophic calcification (e.g. HAC)
- Metastatic calcification: deposition associated with altered serum of calcium/phosphorus e.g. chronic renal disease.
- Idiopathic e.g. Calcinosis circumscripta
Calcinosis cutis
Aural haematoma
What causes a haematoma?
Damaged/ruptured blood vessel bleeds into/under skin.
* Usually traumatic cause, but occasionally linked to clotting factor deficiencies/toxic causes (check history for these)
Describe the cytology you might expect if you sampled a haematoma
- Initially the same as a blood smear although no platelets
- Macrophages engulfing RBCs and fibroblasts may appear
Describe treatment of a haematoma
- Find cause and address if necessary
- Usually self-limiting - keep quite, apply pressure bandage
- If acute, severe haemorrhage, identify source and ligate. Consider antibiotic cover if risk of secondary infection.
- In some cases, surgery may be required e.g. aural haematoma
Seroma
accumulaton of sterile fluid (filtrate of blood) under a wound.
* The swelling is soft, non-painful, and there is not heat on palpation.
* FNA shows straw-coloured/blood-tinged fluid.
Describe management of a seroma that formed after surgery
- Conservative unless refractory or causing wound disruption (may take several weeks)
- If pressure bandaging, change bandage every 48hrs
- Keep animal quiet and confined
- Repeated drainage only if size is causing discomfort (likely to reform and risk of introducing infection)
- If severe: surgical debridement, flushing with isotonic solution, careful apposition of tissues, insertion of Penrose drains, biopsy and culture
Arthropod bite granuloma
Describe the management of an arthropod bite granuloma
- Check no evidence of retained arthropod/mouthparts (esp tick)
- May resolve without treatment
- Could do short course topical corticosteroid
- If not resolving, consider surgical removal, submission for histopath, tissue culture to confirm diagnosis (would need to be off corticosteroids for 2 weeks before sampling for histology)
Panniculitis: inflammation of the subcutaneous fat.
* Presents as single/multiple nodules ± draining sinuses
* Easily confused with bacterial abscess
* Can be sterile or infectious in origin
This is the FNA from an animal presenting with multiple nodules and some draining sinuses. What are your thoughts?
- This FNA shows pyogranulomatous inflammation with background fat
- Presenting signs consistent with panniculitis
- Need to take samples for histopath and bacterial and fungal tissue culture -> rule out infection as initial step
Describe the management of panniculitis
- Correct underlying cause if possible
- e.g. foreign material -> excise if solitary lesion
- e.g. 2 address nutritional imbalances
If still no resolution
* If solitary lesion -> surgical excision if possible
* If multifocal lesion -> immunosuppressive therapy (must check for infection prior to starting this!)
Mast cell tumour
(This is a round cell tumour)
