Cutaneous masses Flashcards
Approach to cutaneous masses, cytology of cutaneous masses
What are the groups that cutaneous masses can fall into?
- Inflammatory (infectious, non-infectious)
- Neoplastic
- Non-neoplastic, non–inflammatory i.e. cysts
Describe what is meant by a nodule
- A solid swelling of tissue >1cm
- Circumscribed, solid elevation
- Usually extends into deeper skin layers
Describe what is meant by a cyst
- An epithelium lined cavity containing fluid or solid material
- Smooth, well-circumscribed, fluctuant/solid
- If emptied, will fill up again
Give examples of swellings of non-dermatological origins
- Hernias
- Oedema
- Emphysema
- ## Mammary tumours
Describe emphysema
- Gas in subcutaneous tissue
- Crepitant without pain or swelling, feels like bubble wrap
What are the potential causes of emphysema?
- Severe respiratory disease or lung puncture
- Introduction or air through cutaneous wound
- Rumenotomy or rumen cannulisation
- Clostridial infections (gas produced by clostridial organism)
Explain the role of FNAs in the diagnosis of cutaneous mass lesions
- Gives an idea of the cellular processes taking place in a lump
- Degree of exfoliation can give indication of what cell types are present
- Can identify if there are microbes present, normal cells, inflammatory cells, neoplastic cells
What is required in order to be able to diagnose a cutaneous mass lesion?
- History
- General clinical examination
- Dermatological examination
- Cytology
- Tissue biopsy
- +/- immunohistochemistry
- ## +/- tissue culture
Why is age important in the history for the diagnosis of a cutaneous mass lesion?
- Certain lesions are more likely at certain ages
- E.g. <4mo: juvenile cellulitis, >2yo: histiocytoma (dog), >6yr: neoplasia
What should be included in the history for a cutaneous mass lesion?
- Age
- Travel
- Breed
- History of trauma/fight
- Systemic signs
- Speed of onset of tumour
- Prior history of neoplasia
- Recent injections
Why is travel an important part of the history for cutaneous mass lesions?
- Leishmaniasis
- Systemic fungal disease
- Exotic diseases such as the above can cause cutaneous masses
What could paraneoplastic signs be suggestive of with a cutaneous mass lesion?
e.g. haematemesis with mast cell tumour
What may respiratory signs, weight loss and lethargy be suggestive of with a cutaneous mass lesion?
- Systemic/metastatic neoplasia
- Systemic function infections
What may depression or inappetance be suggestive of with cutaneous mass lesions?
Some microbial infections, abscesses
With what types of cutaneous masses may pyrexia occur?
With systemic/severe cutaneous microbial infections, abscesses
What types of cutaneous masses might cause peripheral lymphadenopathy?
- Neoplastic (metastatic spread to lymph nodes)
- Infectious/inflammatory causing reactive hyperplasia/lymphadenitis if spread
List the features that should be identified and characterised by the dermatological examination of a cutaneous mass
- Solitary or multiple lesions?
- Area of body and size
- Well vs ill defined
- Freely moveable or attached
- Draining tracts/sinuses?
- Pitting on pressure
- Presence or absence of pain
- Inflammatory (can indicate neoplastic or inflammatory lesion)
What is the advantage of no-suction FNAs?
Less likely to damage cells
What cytology techniques can be used in the investigation of cutaneous masses?
- FNA
- Impression smears
What would you expect to see on cytology of an inflammatory mass lesion?
- May be sterile or infectious, acute or chronic
- May see microbes
- Neutrophils (acute), macrophages (chronic)
- +/- eosinophils
What would you expect to see on cytology of a neoplastic mass lesion?
Round, epithelial or spindle cells in neoplastic arrangement i.e. conal population, pleomrphism etc.
Describe the cytological appearance of a cystic mass lesion
- Depends on what is lining the epithelium
- Amorphous collection of cells
What are the key limitations of cytology in the investigation of cutaneous mass lesions?
- Not all cell-types are shed easily, may not always be representative/diagnostic
- May take an unrepresentative sample
- Gives no information re. the tissue architecture, therefore cannot grade neoplasm if present
What are tissue biopsies used for with cutaneous mass lesions?
To confirm putative diagnosis from FNA or where FNA is inconclusive, or for tissue culture where needed
Describe an elliptical incisional biopsy
- Includes margin of normal to abnormal
- Taken from representative area
- Need to remove whole biopsy tract when mass is removed
Describe an elliptical excisional biopsy
- May cure benign, non-infiltrative neoplasms
- Remove deeper tissue en bloc so can assess all margins, but can nerver confirm 100% excision
- DO NOT perform if suspect infiltrative mass
When are punch biopsies mostly used?
For inflammatory lesions, not so useful for neoplasms
When should lymph nodes be biopsied?
- FNA all enlarged lymph nodes
- If firm node negative for neoplasia on FNA, take excisional biopsy under GA for histopath
Outline the role of immunohistochemistry in the diagnosis of cutaneous mass lesions
- Labels cell-surface markers to help identify pheotype of cells in neoplasms
- Highly anaplastic cells may still remain unidentifiable
When and how should tissue culture be performed in the diagnosis of cutaneous mass lesions?
- If deep infection is a possibility
- Take when sampling for histopath to save second procedure
- Trim off surface epidermis to avoid contamination of sample with surface organisms or antibacterial scrub solutions
List the potential origins of cutaneous tumours
- Epithelium
- Mesenchyme (spindle cell)
- Round cells
- Melanocytes
- Metastases from non-cutaneous neoplasm
List the most common causes of cutaneous tumours of farm animals
- Papillomatosis
- Enzootic bovine leukosis
- Sporadic bovine leukosis
- Lymphosarcoma in pigs
- Cancer eye (SCC in cattle, usually UV associated, periorbital or orbital)
- SCC of sheep and goats: often vulvae, perineal, pinnal, papilloma-virus associated in sheep
Compare the proportion of benign to malignant skin tumours in dogs and cats
- Most skin tumours in dogs are benign (2/3)
- Most skin tumours in cats are malignant (2/3)
List the most common malignant skin tumours of dogs (inn order from most to least common)
- Mast cell tumour
- Soft tissue sarcomas
- Malignant melanoma
- Squamous cell carcinoma
- Epitheliotropic lymphoma
Name the main benign skin tumours of dogs
- Histiocytoma
- Papilloma
- Lipoma
- (histiocytoma and papilloma may regress spontaneously)
- Sebaceous hyperplasia/adenoma
- Melanoma
- Basal cell tumour
List the most common feline skin tumours (in order from most to least common)
- Fibrosarcomas
- Squamous cell carcinomas
- Basal cell tumours
- Mast cell tumours
What are the 3 golden rules in the approach to cancer cases?
- Establish the diagnosis (type and grade of tumour)
- Establish the stage of disease
- Investigate any complications
What are the treatment options for cutaneous neoplasia?
- Surgery
- Chemotherapy
- radiotherapy
In what cutaneous tumours would a 1cm excisional margin be sufficient?
- Low grade mast cell tumours
- Grade 1 soft tissue sarcomas
- Well differentiated squamous cell carcinomas
In what cutaneous tumours would a 2cm excisional margin be sufficient?
- Intermediate grade mast cell tumours
- Malignant oral tumours e.g. fibrosarcoma, SCC, poorly differentiated carcinomas
- Grade 2 and 3 soft tissue sarcomas
In what cutaneous tumours would a 3cm excisional margin be required?
- Osteosarcomas that have invaded soft tissues
- Feline vaccine-associated sarcomas
What natural barriers will limit the spread of tumours?
Collagen-rich, relatively avascular structures e.g. fascia, tendons, ligaments, cartilage
Describe the typical presentation of mast cell tumours
- Single or multiple nodules, cutaneous or subcutaneous
- May mimic other masses or inflammatory conditions
- Over half on trunk, 25-40% on extremities, 10% on head and neck
- Scrotum, perineum, back and tail can be affected
- Occasionally extracutaneous sites such as conjunctiva, larynx, oral mucosa
- Often poorly haired
- May be inflammatory: paraneoplsatic clinical signs, visible inflammation, pruritus, changing size of mass
What signs could histamine from a mast cell tumour cause?
- Inflammation, pruritus
- +/- vomiting, gi ulceration and melaena
- Occasional oedema/anaphylaxis
- Collapse
What signs could heparin from a mast cell tumour cause?
Local bruising and perioperative bleeding
What is a potential outcome of proteases released from mast cell tumours?
Slow wound healing
What is required in the work up of a suspected mast cell tumour?
- FNA (diagnoses most MCTs)
- Histopathology for grading
- Assessment and aspiration of local LNs
- Ultrasound of liver and spleen (no other imaging needed)
Compare the metastatic potential of well, intermediate and poorly differentiated mast cell tumours
- Well: rarely metastasise (<10%)
- Intermediate
uncommonly metastasis (5-20%) - Poorly: >75% metastasise
Give the treatment options for mast cell tumours
- Surgical removal best
- Some new drugs available: masivet, palladia
- Chemotherapy: masivet, palladia, prednisolone+vinblastine+chlorambucil
- Radiotherapy
Describe the typical appearance of feline squamous cell carcinoma
Usually develop on unpigmented nasal planum, pinnae, eyelids
Describe the metastatic potential of feline squamous cell carcinomas
- Low metastatic potential
- Very locally invasice
Discuss the treatment of feline squamous cell carcinomas
- Depends on size and site of neoplasm
- Superficial respond well to all therapies
- Infiltrative need aggressive surgery
Options:
- Surgery: incl pnnaectomy, nasal planectomy
- Photodynamic therapy
- Radiotherapy
- Laser therapy or cryotherapy for early, shallow lesions only
- Imiquimod cream, for early shallow lesions
How can feline squamous cell carcinomas be prevented?
- Sunblock
- Keep indoors in strong sunlight
- UV light blocking film on windows
Discuss the prognosis of canine squamous cell carcinomas
- depends on site
- Nasal planum, legs, trunk have low metastatic potential, surgery good option
- Subungual may require amputation of digit
Describe subungual squamous cell carcinomas in dogs
- Most common canine digital tumour, esp. large black dogs
- Differential: paronychia, as often have secondary infection/inflammation
- Radiography needed
- If see lysis on P3 on radiography or biopsy then amputate digit
What are liposarcomas, fibrosarcomas, myxosarcomas and haemangiopericytomas examples of?
Canine soft tissue sarcomas
Describe the malignancy, diagnosis and treatment of liposarcomas, fibrosarcomas and myxosarcomas
- Variable malignancy, often local infiltration rather than distant metastasis
- Biopsy for diagnosis
- Radical excision after staging, or debulk + radiotherapy
- Chemotherapy of little value due to slow turnover rate of cells
Explain the role of biopsy in the diagnosis of canine soft tissue sarcomas
- Identification of concurrent necrosis/inflammation
- Needed for grading
- Poor exfoliation on FNA
- Often look similar on cytology
Why are haemagioperictyomas different from other canine soft tissue sarcomas?
FNA can yield diagnosis
Describe the appearance, metastatic potential, treatment and prognosis for haemangiopericytomas
- Low grade tumours on limbs
- Low metastatic potential
- Treatment is wide excision or debulk +radiotherapy
- Often recur following excision, not life threatening but are annoying and difficult to deal with
Compare feline and canine fibrosarcomas
- Generally behave the same and can be treated in the same way
- Exception is injection site sarcomas in cats
What should be done if suspect an injection site sarcoma?
- Report via suspected adverse reaction reporting service
- Consult oncologist after biopsy but before surgery
Name the 2 types of primary cutaneous lymphoma
- Epitheliotropic lymphoma (mycosis fungoides, T cell lymphoma)
- Non-epitheliotropic lymphoma (B cell lymphoma)
Describe the different manifestations of epitheliotropic lymphoma
- Generalilsed: scale, pruritus, exfoliative dermatitis
- Foci of erythroderma, crusting, ulceration
- Mutliple dermal nodules, erythematous plaques
- Mucocutaneous lesions (depigmenting)
- All are chronic and may wax and wane initially
Compare the prognosis of epitheliotropic and non-epitheliotropic lymphomas
- Epitheliotropic better, unpleasant due to extent of lesions but does not kill animal very quickly
- Non-epitheliotropic carries grave prognosis, metastasise rapidly. Presence of nodules carries worse prognosis still
Discuss the treatment of non-epitheliotropic lymphomas
- Median survival time is only months
- Chemotherapy: retinoids, CCNU (lomustine) or COP
- Surgery possible if solitary/localised
- Surgery or radiotherapy if localised epitheliotropic lymphoma or lips/mouth
Define a cyst
An epithelium lined cavity containing fluid or solid material
Describe the contents of follicular, apocrine and sebaceous cysts
- Follicular: cornified debris, tends to look very pus-y
- Apocrine: apocrine secretions
- Sebaceous: sebaceous secretions
Explain the development and importance of infection in cysts
- Cysts may rupture, leading to inflammation and potentially infection
- Infection and inflammation must be resolved before excision
Explain what is meant by dermoid cysts
- Congenital defect, especially common in Rhodesian Ridgebacks, often located on dorsal midline neck/trunk
- Filled with hair/keratinous material
Explain the significance of dermoid cysts
- Benign in the sense that it is not cancer, but cause substantial space occupying problem
- May extend to dura mater and cause neurological problems
What are the treatment options for non-infiltrating lipomas?
- Are benign skin mass
- Can leave if monitor intermittently following identification, and if are slow growing and causing no problem
- Excision if are causing problems
Describe the gross appearance, cytological appearance and treatment options for sebaceous hyperplasia/adenoma
- Small cauliflower-like warts
- If slow growing and well-circumscribed can leave and monitor
- Excise if any change or become traumatised
- On aspiration wil see sebaceous cells/sebocytes
In what groups of animals are histiocytomas more commonly found?
- Young dogs
- Dogs on oclacitanib
Where are histiocytomas commonly found?
On the extremities
Describe the treatment of histiocytomas
- Frequently resolve spontaneously
- Do not use steroids, may slow regression
- Lymphocytes may be seen at base of tumour as immune system deals with these
Describe the appearance of melanomas
Usually well defined, deeply pigmented dome-shaped lesions in pigmented skin
Compare the prevalence and location of benign and malignant melanomas
- > 85% are benign, but still use wide excision
- Mucocutaneous or digital melanomas are potentially malignant with widespread metastases
Compare basal cell tumours in the dog and cat
- Usually benign in dog (depending on location)
- Aggressive characteristics in cats
Describe the appearance of basal cell tumours in cats
- Solid, ulcerated or cystic
- Most common pigmented tumour in cats
Compare the growth and treatment of basal cell tumours in dogs and cats
- In dogs are slow growing, wide excision used to cure
- In cats, aggressive on cytology/histopathology but low-grade behaviour
- Excise with as wide a margin as possible
List the classifications for inflammatory lumps
- Can be: neutrophilic, eosinophilic,lymphoplasmalytic or granulomatous
- Identify as: acute or chronic
- Identify as: septic or no organisms observed
List the classifications of neoplastic lumps
- Cell type: epithelial, round, spindle
- Activity: benign or malignant
List the classifications of cystic lumps
- Haematoma
- Seroma
- Sialocoele
- Epithelial/follicular
Explain how inflammation with tissue cells may be found on cytology of a lump
- May be primary neoplasia with secondary inflammation
- May be primary inflammation with secondary hyerplasia, fibroplasia or granulation tissue
What are smudge cells and describe their appearance
- Aka broken/basket cells
- Are damaged cells with disrupted cytoplasm, bare nuclei, may look neoplastic but can be ignored
- Nuclei enlarged, chromatin coarse, nucleoli may become visible
What are the main causes of acute inflammatory lumps?
- Bacterial infection
- Foreign body
- Trauma
- Tumour necrosis
What are the cytological diagnoses of inflammatory lesions?
- Septic inflammation
- Pyogranulomatous inflammation
- Steatitis/panniculitis
- Granulomatous inflammation
- Eosinophilic inflammation
Describe the common cytological appearance of acute inflammation
Suppurative and neutrophilic
What features indicate infection on cytology of a cutaneous lump?
- Marked inflammatory response
- Bacteria in neutrophils, or degenerate neutrophils
- Single population of bacteria
What features indicate contamination, rather than infection, on cytology of a cutaneous lump?
- No inflammation
- Mixed population of bacteria
- Bacteria not within neutrophils
Describe the features that indicate neutrophils are degenerate
- Karyolysis (nuclear swelling)
- Pale staining
- Ragged outline
- “Fluffy” appearance
Describe the appearance of non-degenerate, normal neutrophils
- Similar to those in circulation
- Hypersegmentation followed by pyknosis is the normal pattern of degeneration of neutrophils
Describe the key cytological features of benign tumours
- Small, siimilar sized cells, small uniform nuclei
- Low nuclear:cytoplasmic ratio
- Smooth granular chromatin
- +/- 1 or 2 small nucleoli, smooth regular shape
- Smooth/invisible nuclear membrane, cytoplasm visible around nucleus
- Ordered cell arrangement
- Cells and nuclei parallel
- Exception is lymphoid tumours
List the subclasses of criteria of malignancy
- Abnormal cell location
- Architectural criteria
- Cell features
- Nuclear features
- Cytoplasmic features
Describe the location criteria of malignancy
Abnormal location e.g. lymphocytes found in skin sample
Describe the architectural criteria of malignancy
- Haphazard cell arrangement
- Loss of cohesion (caused by downregulation of adhesion molecules)
- Loss of contact inhibition
What does the loss of cohesion in malignant tumours mean for sampling?
- Loss of cohesion means increased exfoliation
- Often leads to a hypercellular sample
Describe the cell features of malignancy
- Macrocytosis: large cells
- Anisocytosis: variation in cell size (3-4x)
- Find cell of abnormal cell type with smallest size, find biggest, estimate how many times smallest fits into biggest
- ## Normal is 1-1.25x difference, any larger indicates malignancy
Describe the nuclear criteria of malignancy
- Anisokaryosis: vaariation in nuclear size
- Multinucleation
- Coarse or clumped chromatin
- Nucleoli: prominent, large, angular, irregular, variably sized
- Increased mitotic activity and atypical mitoses
- Nuclear fragmentation and thickening of the membrane
- High or variable Nuclear:Cytoplasmic ratio
