Appraoch to cutaneous masses Flashcards
When presented with a cutaneous mass, what could it be? How can skin masses be classified?
Define a nodule and a cyst?
Nodule
Circumscribed, solid elevation >1cm diameter; usually extends into deeper skin layers (papule <1cm)
Cyst
Epithelium-lined cavity, containing fluid or solid material
Smooth, well-circumscribed; fluctuant/solid
Remember swellings of non-dermatological origins?
- Hernias
- Oedema
- soft, painless swelling
- pits on pressure
- Clear fluid on FNA
- Emphysema = gas in subcutaneous tissue (feels like bubble wrap)
- crepitant without pain or swelling
- caused by
- Severe respiratory disease or lung puncture
- Introduction of air through cutaneous wound
- Rumenotomy or rumen cannulisation
- Clostridial infections
- Mammary tumours
Biopsy early lesion; avoid old ulcers, secondary infection
When is an Elliptical incisional indicated?
- Include margin
- Take from representative area
- Ensure to remove whole biopsy tract when mass removed….
When is an elliptical excisional biopsy indicated?
Elliptical excisional
- May cure benign, non-infiltrative neoplasms
- Remove deeper tissue en bloc so can assess all margins (send untrimmed), but can never confirm 100% excision
- Not if suspect infiltrative mass
- Do not do an excisional if you suspect an infiltrative mass.
What type of biopsy would you take from these cases?
Ill-defined mass on plantar aspect of hind foot
Incisional
1cm well-defined mass on flank, detected at vaccination. Had been present, unchanged, for at least 6 months…
Excisional
But what margins ? MASSIVE MARGINS 2-3cm atleast
What are the origins of cutaneous neoplasms?
Epithelium –> epithelial neoplasm
Mesenchyme –> mesenchymal (spindle) cell neoplasms
Round cells –> round cell neoplasms
Others
Melanocytes
Metastasis from non-cutaneous neoplasm
What are common skin tumours of farm animals?
Papillomatosis –
- See ‘Viral skin disease’ lecture
Enzootic bovine leukosis (EBL)
Sporadic bovine leukosis
Lymphosarcoma in pigs
“Cancer Eye”
- Squamous cell carcinoma (periorbital/orbital) in cattle; usually UV-associated
Squamous cell carcinoma (sheep, goats)
- Often vulvar, perineal, pinnal
- ?papilloma-virus-associated aetiology in sheep
How common are skin neoplasms in dog and cat?
25-58% of all neoplasms
Discuss canine skin tumours?
Most benign (approx 2/3)
- Cured with wide local excision
Histiocytoma and papilloma may regress spontaneously
Important to recognise malignant tumours and know how to act!
- Mast cell tumour (11%)
- Squamous cell carcinoma (SCC) (1%)
- Malignant melanoma (3%)
- Soft tissue sarcomas (4%)
- Epitheliotropic lymphoma
Discuss feline skin tumours?
Most malignant (approx 2/3)
Most common feline skin tumours
- Fibrosarcomas (25%)
- Squamous cell carcinomas (SCC) (17%)
- Basal cell tumours (15%)
- Mast cell tumours (7%)
How should Cancer Cases be approached?
Three Golden Rules:
- Establish the diagnosis (type and grade of tumour)
- Establish the extent/stage of the disease
- Investigate any complications
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)
Discuss surgical margins for different kinds of tumours?
1cm
low-grade mast cell tumours, grade 1 ST sarcomas, well differentiated squamous cell carcinomas SCC
2cm
for intermediate grade mast cell tumours, malignant oral tumours (fibrosarcoma, SCC, poorly differentiated carcinomas), grade 2 and 3 soft tissue sarcomas
3cm
for osteosarcomas that have invaded soft tissues, feline vaccine-associated sarcomas
What is common MCT-clinical presentation?
- Single or multiple nodules- cutaneous (dermal) or subcutaneous
- May mimic other masses (lipomas, ST sarcomas) or inflammatory conditions (cellulitis or acral lick dermatitis)
- Over half of them on the trunk, then extremities (25-40%) and head and neck (10%)
- Scrotum, perineum, back and tail can be affected
- Occasionally extracutanous sites such as conjunctiva, larynx, oral mucosa
- Intracytoplasmic granules contain inflammatory mediators –> paraneoplastic clinical signs…
- +/- visible inflammation, pruritus
- +/- increase/decrease in size of mass – care with palpation!
- Histamine –> +/- vomiting, GI ulceration & melaena, occasional oedema/anaphylaxis/collapse
- Heparin –> local bruising and perioperative bleeding
- Proteases –> slow wound-healing
How should a suspected MCT be worked up?
- FNA- diagnoses 92-96% MCTs
- Histopathology required for grading
- Assessment and aspiration of local lymph node
- Imaging-ultrasound of liver and spleen
- Not thoracic X-rays
What does well differentiated mean?
When referring to tumors, it means it closely resembles the appearance of the parent tissue. For example, a well differentiated colon carcinoma closely resembles the benign glands of the colon
With regards to mast cell tumours how does histological grade of differentiation denote how likely a tumour is to metastasis?
Well differentiated: rarely metastasise (<10%)
Intermediate differentiated: uncommonly metastasise (5-20%)
Poorly differentiated: >75% metastasise
How is a mast cell tumour treated?
Management
- Surgical removal**
- Chemotherapy
- Masivet (masitinib)
- Palladia (toceranib phosphate)
- Prednisolone, vinblastine, chlorambucil
- Radiotherapy
Describe the clincal signs of feline squamous cell carcinomas?
- Usually seen on unpigmented nasal planum, pinnae, eyelids
- Have low metastatic potential, but locally invasive (NB still check chest radiographs, FNA drainage LNs before extensive therapy)
How should feline squamous cell carcinomas be treated?
- Treatment depends on site and size of neoplasm.
- Superficial tumours respond well to all therapies; infiltrative tumours need aggressive surgery
- Prevention:
- Sunblock
- keep indoors in strong sunlight
- UV light blocking film on windows?
- Treatment options:
- Surgery: including pin nectomy, nasal planectomy .
- Photodynamictherapy
- Radiotherapy
- Laser therapy or cryotherapy (early, shallow lesions only)
- Imiquimod cream (early, shallow lesions)
Discuss the clinical signs of canine squamous cell carcinoma?
Less common than in cat
Prognosis depends on site:
- Nasal planum, legs, trunk
- low metastatic potential –> surgery (NB cosmetic considerations)
- Subungual
- Most common canine digital tumour! Esp large black dogs.
- d/d paronychia as often secondary infection/inflammation (Paronychia is a nail disease that is an often-tender bacterial or fungal infection of the hand or foot where the nail and skin meet at the side or the base of a finger or toenail.)
- Biopsy, esp if see lysis of P3 on radiography –> amputate digit
Discuss canine soft tissue sarcomas (spindle-cell sarcomas)?
Canine soft tissue sarcomas
Liposarcomas, fibrosarcomas, myxosarcomas
- Variable malignancy – often local infiltration, cf distant metastasis
- Biopsy to diagnose
- concurrent necrosis/inflammation: needed for grading
- poor exfoliation on FNA
- Usually –> radical excision after staging (or debulk + radiotherapy)
- Chemotherapy of little value
How are canine Haemangiopericytomas an exception of soft tissue sarcomas?
- Low-grade tumours, on limbs
- Low metastatic potential
- FNA can yield diagnosis
- –> Wide excision or debulk + radiotherapy
Discuss feline soft tissue sarcomas?
Generally behave as canine soft tissue sarcomas and treated similarly
- NB do not ‘shell out’ mass in pseudocapsule - ‘the first surgery is the best surgery’…
Except
- ‘Injection site sarcomas’
- Usually interscapular region on cats
- If suspect, inform pharmaceutical company via yellow ‘suspect adverse reaction card’
- Consult oncologist after biopsy but before surgery
Describe the clinical signs of primary cutaneous lymphoma?
1. Epitheliotropic lymphoma (mycosis fungoides) (T-cell lymphoma)
Manifestations:
- Generalised scale, pruritus
- Foci of erythroderma, crusting, ulceration
- Multiple dermal nodules/erythematous plaques
- Mucocutaneous lesions (may depigment)
2. Non-epitheliotropic lymphoma (B-cell lymphoma). Less common than 1.
What are the prognosis’ for non-epitheliotrophic and epitheliotrophic lymphoma?
Non-epitheliotropic lymphoma
Rapid metastasis, grave prognosis
Epitheliotropic lymphoma
Chronic, may wax/wane initially
Discuss Non-neoplastic non-inflammatory skin tumours – ‘cysts’?
- Cutaneous cysts - common
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
- May rupture –> inflammation +/- infection
- Resolve inflammation/infection before excision
What is this?
Dermoid cyst
- Congenital defect, esp Rhodesian Ridgeback
- Cysts dorsal midline neck/trunk
- May extend to dura mater, causing neurological problems
- Filled with hair/keratinous material
Describe common benign skin neoplasms?
All very common!
Non-infiltrating lipoma
- Can leave if monitor intermittently (if positively identified, slow-growing and causing no problem)
- NB d/d mast cell tumour, haemangiopericytoma
Sebaceous hyperplasia/adenoma
- Small cauliflower-like ‘warts’
- If slow-growing and well-circumscribed, may leave and monitor. Excise if any change or traumatised
What is this?
- Histiocytoma
- Common rapidly-growing well-demarcated masses. May ulcerate
- Frequently young dogs
- Commonly on extremities
- Increased frequency in dogs on oclacitanib (Apoquel)
- Histiocytes (round cells) on FNA – d/d MCT
- Frequently resolve spontaneously – do not use steroids as may slow regression
Discuss melanomas?
- Usually well-defined deeply-pigmented dome-shaped lesions in pigmented skin
- >85% benign –> wide excision
- But mucocutanous (eg eyelid, lip) or digital melanomas potentially malignant with widespread metastasis
Discuss the basal cell tumour?
- Dog: usually benign, slow-growing. Wide excision to cure
- Cat: common
- Solid, ulcerated or cystic
- The most common pigmented tumour in cats (d/d melanoma)
- Aggressive characteristics on cytology/histopathology but low-grade behaviour
- Excise with as wide a margin as possible
What are the take home messages about cutaneous masses?
- Most canine tumours of low malignancy
- Most feline tumours of high malignancy
- Address promptly and diagnose definitively
- Perform appropriate treatment:
- Surgery – appropriate margins, planned in advance
- Radiotherapy
- Chemotherapy
If in doubt, consult an oncologist!
