Specific disorders of the skin Flashcards
What are the four surgical margins for tumour removal?
What are the 3 different histologic margin categories following tumour removal?
In general, how long after surgery is it advised to start chemotherapy?
7-10 days
In general, how long after surgery is it advised to start radiation therapy?
1-3 weeks (the acute inflammatory phase and proliferative phase are most sensitive to radiation effect).
How long should surgery be delayed following pre-operative radiation therapy?
Ideally 3-4 weeks to allow clearance of acute radiation effects.
Describe the WHO-TNM classification system for tumors of epidermal or dermal origin.
Do mesenchymal cell tumours more commonly spread by hematogenous or lymphatic routes?
Hematogenous. Epithelial tumours spread more commonly by lymphatics.
What size pulmonary nodules can thoracic radiography and CT scan detect, respectively?
Radiographs: 1-2 mm
CT scan: 5-9 mm
What are the functions of the lymphatic system?
- Transport of lymph from tissues and organs, lipids from the intestine and liver, and waste products and fluids from the local sites.
- Immune response. Lymphatic vessels drain into lymphatic ducts and then into lymph nodes.
Is lymph flow passive or active?
Both. Active constriction of smooth muscle in the lymphatic walls, passive through outside pressure from musculature with lymphatic valves preventing retrograde flow.
What are the primary cell types in the cortex and medulla of the lymph node?
Cortex: B and T lymphocytes.
Medulla: lymphocytes, macrophages and plasma cells. Sinuses between medullary cords help to filter and phagocytose foreign material.
What is lymphangitis? What are some clinical signs?
Secondary inflammation of the lymphatic system, generally secondary to systemic disease.
Can cause pyrexia, anorexia and depression. Persistent edema can result in irreversible thickening of the skin and subcutis.
What is lymphadema?
Reduced lymphatic transport capacity resulting in interstitial edema. Can be primary (congenital and rare) or secondary.
Aside from lymphadema, what are some other potential causes of interstitial edema?
High lymphatic load from venous hypertension, portal hypertension, venous obstruction, arteriovenous fistula, hypoproteinemia. Increased vascular permeability from vasculitis.
What are some causes of secondary lymphadema?
Neoplasia, trauma, surgery, radiation therapy, parasitic infection, chronic lymphangitis.
What are some treatment options for lymphadema?
Bandaging, benzopyrones (coumarin) although may cause hepatotoxicity and not reported in veterinary medicine. Diuretics have no effect as edema not caused from water retention.
What diagnostics can be used to identify lymphadema?
Direct contrast lymphangiography or indirect lymphoscintigraphy +/- CT or MRI.
What are the 5 types of round cell tumours observed in dogs and cats?
Lymphoma, histiocytoma (or malignant histiocytosis), plasma cell tumour, mast cell tumour, TVT.
What is the most common skin tumour in dogs and cats, respectively?
Dogs: mast cell tumour
Cats: SCC
What is the typical treatment for papillomatosis in young dogs?
Nothing, usually resolve within 3 months. Thought to have an underlying viral cause.
What is actinic keratosis?
A precancerous solar induced lesion which may progress to SCC.
What is Bowenoid carcinoma in situ?
A rare form of multicentric SCC in situ presenting as multifocal crusted plaques.
In what percentage of SCC in dogs and cats are ultraviolet light specific mutations in the P53 gene reported?
Dogs: 30-38%
Cats: 40-82%
What are the most common locations of SCC in dogs and cats?
Dogs: Nail bed, scrotum, legs and anus.
Cats: pinnae, eyelids, temporal area, nasal planum.
Which breeds are most commonly affected by nasal planum SCC in dogs?
Male labrador and golden retrievers
White cats have a ___ times higher risk of SCC compared to cats of other coat colours?
13
What is the median survival time for cats following pinnectomy or nasal planectomy for SSC?
673 days
Based on tumour stage, when should aggressive surgery indicated over alternative therapies for cutaneous SCC?
Aggressive surgery gives the best prognosis for tumours greater than stage T2.
Name 6 alternative therapies for cutaneous SCC aside from surgical excision.
- Cryosurgery
- Plesiotherapy (form of superficial radiation therapy)
- Radiation therapy
- Photodynamic therapy
- Chemotherapy
- Immunomodulatory therapy
For what size SCC lesions is cryosurgery considered an appropriate treatment option?
Up to 5mm in diameter. MST of 682 days.
What depth of tissue penetration does strontium plesiotherapy achieve when treating SCC?
3mm
Is photodynamic therapy appropriate for treatment of deep cutaneous SSC lesions?
No - only has superficial penetration. In one study had 100% control of T1 non invasive tumours and only 18% for T2 invasive tumours.
What is electrochemotherapy?
Use of locally applied electrical field pulses to induce an increased uptake of a systemically administered chemotherapeutic drug.
In what percentage of canine and feline cutaneous SCC is there COX-2 expression?
100%, although effects of NSAIDs on SSC have not been investigated in dogs and cats. This is compared to only 9-18% of oral feline SCC.
What is an example of an immunomodulatory agent used in the treatment of cutaneous SSC?
Imiquimod. Has shown efficacy for actinic keratosis in humans. Less favourable results in cats with some systemic side effects.
What axial pattern flap is useful in reconstruction of rostral facial defects following SSC excision?
Angularis oris axial pattern flap
What are the recommended surgical margins for excision of cutaneous SSC in dogs and cats?
Cats: 5mm
Dogs: nasal planum or invasive cutaneous tumours (T3/T4) at least 2cm
List two potential prognostic factors for SSC.
Tumour stage, proliferation fraction, epidermal growth factor receptor expression.
Which breeds of dog are reported to have an increased incidence of basal cell tumour?
Cocker spaniels and poodles. Frequently occur on the head, neck, or shoulders.
Are basal tumours considered aggressive in behaviour?
No, despite often having a high mitotic rate in cats they generally behave in a benign fashion. Surgical excision is typically curative.
What is the recommended treatment for sebaceous gland adenocarcinomas or aggressive sweat gland malignancies?
Wide surgical excision.
Is cytology useful in differentiating between perianal adenomas and adenocarcinomas?
No, histology is typically required.
Are perianal adenomas or adenocarcinomas more common?
Adenomas (58-96% of cases).
Are perianal adenomas and adenocarcinomas both hormone responsive?
No, only perianal adenomas demonstrate sex-hormone responsiveness (most regress following castration of intact males).
What percentage of perianal adenocarcinomas are have metastasis at the time of diagnosis?
15% (most common sites are the regional lymph nodes, lungs, liver, kidneys and bone although distance metastases are uncommon).
What factor has been shown to significantly influence disease free intervals with perianal adenocarcinoma?
Tumour stage
How much of the anal sphincter can be removed with only transient loss of continence?
50%
In what percentage of dogs is hypercalcemia reported with anal sac adenocarcinoma (AGASACA)?
27-53%
What is the percentage metastatic rate of canine AGASACA at diagnosis?
36 - 96%
What is the most common site of metastasis in canine AGASACA?
Sublumbar lymph nodes
In what percentage of dogs is AGASACA an incidental finding?
39%
What imaging modalities may be useful in ruling out bone metastasis in canine AGASACA?
Radiography, nuclear scintigraphy
What are some negative and positive prognostic factors for canine AGASACA?
Positive: surgical excision and lymphadenectomy.
Negative: tumor stage, hypercalcemia, lack of therapy.
What is the MST for canine AGASACA?
16-18 months (with surgery alone 7.9 - 16.6 months). Longest survival times have been reached with a combination of surgery, radiation and mitoxantrone chemotherapy.
What is the reported local recurrence rate after marginal excision of canine AGASACA?
7 - 45%
Is hypercalcemia a common feature of AGASACA in cats?
No
What is the reported MST for AGASACA in cats following marginal excision?
3 months
Is surgical excision of hair matrix tumours typically curative?
Yes
Describe the TMN staging system for soft tissue sarcomas
Are soft tissue sarcomas more common in small, medium, or large breed dogs?
Medium or large
What are the three described grades of soft tissue sarcomas?
Grade 1/low
Grade 2/intermediate
Grade 3/high
Grade is predictive of both distant metastasis and local recurrence.
In what percentage of patients is histologic grade of STS underestimated on pre-operative biopsy?
29% (overestimated in 12%)
What is the most common site of distant metastasis for STS?
Lungs. Reported overall rate of metastasis is 6-17% (<13% grade 1 and 2, 41% - 44% grade 3)
What is the most important prognostic factor for local recurrence of STS?
Clean surgical margins. Other negative reported factors include size, and positive factors are tumor mobility, expansile growth, and reduced depth of invasion.
What are the recommended surgical margins for STS?
2 - 3 cm lateral margins, one fascial plane deep
What are treatment options following incomplete excision of STS?
Reexcision or radiation (comparable response rates with ~15% recurrence). MST following radiation appears to be grade dependent (940 days for grade 3, not reached for grades 1 and 2). MST after surgery alone for grade 3 tumours: 236-856 days.
What was the MST for cats undergoing surgical excision of soft tissue sarcomas? Was this affected by completeness of excision?
MST: >16 months
Yes, MST with incomplete excision <9 months.
What is the recurrence rate of STS following marginal excision?
Grade dependent (grade 1 = 7%, grade 2 = 34%, grade 3 = 75%). On the distal limb grade 1 tumours were associated with prolonged survival following marginal excision in 1 study (MST not reached), with histologic margin not affecting survival time.
Is radiation therapy as a single-modality therapy considered a definitive treatment option for soft tissue sarcoma?
No, considered palliative as does not result in a durable response. More effective following surgical excision or debulking.
Does chemotherapy improve prognosis for patients with soft tissue sarcoma?
Uncertain, but typically recommended in high grade soft tissue sarcomas due to the propensity to metastasize (40%).
Do perivascular wall tumours have a more or less aggressive biologic behaviour to canine STS in general?
Less aggressive. Expansile lesions also more common the distal extremity, resulting in equal rate of recurrence compared to other locations even with marginal excision.
What is histologically low grade and biologically high grade fibrosarcoma?
A subtype of fibrosarcoma that occurs in young dogs in the oral cavity. Appears histologically low grade but has high grade biologic behaviour. Prognosis is guarded.
What immunohistochemistry marker can be used for differentiation of peripheral nerve sheath tumours?
Vimentin. They arise from Schwann cells, perineural fibroblasts, or both.
What is the reported incidence of feline injection site sarcomas?
1 to 10 per 10,000 cats
Which vaccines are associated with the highest risk of feline injection site associated sarcoma?
Inactivated vaccines. Two-fold increased risk for rabies, and five-fold for FeLV.
What is the reported local recurrence rate for feline injection site sarcomas?
70%
What is the most common tumour type associated with feline injection site sarcoma?
Fibrosarcoma (79-93%)
What is the most common site of metastasis for feline injection site sarcomas?
Lungs (0 - 24%)
What are significant prognostic factors for survival for feline injection site sarcomas?
Aggressive surgery with wide margins, local recurrence, occurrence of distant metastasis, number of surgeries, and size. Most important prognostic factor for local recurrence is clean surgical margins. Aberrant cytoplasmic p53 expression associated with shorter time to recurrence.
What is the MST for feline injection site sarcomas?
576 - 608 days with surgery alone. Disease free interval much shorter after marginal excision (325-419 days wide excision, 79 days marginal).
What surgical margins are recommended for feline injection site sarcomas?
With 4-5 cm lateral margins and one fascial plane deep local recurrence of 39% reported. With 5cm lateral margins and 2 fascial planes deep 14% recurrence (overall median survival 901 days).
Is radiation therapy beneficial in instances of marginal excision of feline injection site sarcomas?
Yes, has been shown to increase disease free interval and survival times. More effective on microscopic rather than macroscopic tumour.