Dermatopathology 3 Flashcards
Which vitamins are involved in vitamin responsive dermatoses (hypovitaminoses)?
- Vitamin A
- Vitamin E
- Vitamin B
What is the effect of vitamin A responsive dermatoses?
Squamous epithelial hyperkeratosis - follicular keratosis
What is the effect of vitamin E responsive dermatoses?
Panniculitis (painful nodules/bumps under the skin) due to steatonecrosis (fat necrosis)
(Lack of antioxidant protection)
What is the effect of vitamin B responsive dermatoses?
Dry seborrhoea (oily skin) with alopecia
What is the normal role of zinc within the skin?
Involved in the production of the stratum corneum
How does a zinc deficiency affect the skin?
Leads to an inability of the stratum corneum to shed and be normally replaced causing hyperplasia and crusting
Which 3 hormonal imbalances can lead to skin lesions?
- Hyperadrenocorticism
- Hyperoestrogenism
- Hypothyroidism
What is superficial necrolytic dermatitis?
“Red, white and blue” epidermal disease, alternating severe parakeratotic hyperkeratosis (red), spongiosis and oedematous spinous layer (white) and basal layer hyperplasia (blue)
What is the pathogenesis of superficial necrolytic dermatitis linked to?
Glucagon secreting pancreatic tumours and end stage liver failure
Describe the gross lesion distribution and appearance of superficial necrolytic dermatitis
- Symmetrical and bilateral on lips, periocular skin, pinna and distal extremities
- Areas of erythema (reddening), erosion, ulcers and crusts
Describe the histological appearance of superficial necrolytic dermatitis
- White represents water inside the spinous keratinocytes (second layer of the skin) = ballooning degeneration
- On top of this layer is a very prominent stratum corneum which is very protein rich so is normally very red
- Blue layer means there is proliferation of the basal layer – which should normally be one cell thick
What is the other name of superficial necrolytic dermatitis?
Hepatocutaneous syndrome
What is dermal atrophy?
Skin becomes thinner at every level
What is the cause of Cushings disease?
Hyperadrenocorticism
- pituitary tumour, adrenal tumour or iatrogenic administration
What is Calcinosis cutis?
The accumulation of calcium salt crystals in your skin
Describe the gross lesion distribution and appearance of Cushings
- Bilateral and symmetrical hypotrichosis and alopecia of trunk, abdomen
- Skin is diffusely thinned and less elastic
- Hyperpigmentation, comedones and calcinosis cutis are also observed
- Dermal atrophy, deposition of calcium
Why do animals with Cushings present with a pot belly?
Due to extreme thinning and decreased elasticity of the skin of the abdominal wall which can no longer support the weight of the organs
Describe the histological appearance of Cushings
Diffuse cutaneous atrophy with orthokeratotic hyperkeratosis and follicular keratosis
What are the possible causes of Hyperoestrogenism?
Polycystic ovaries and functional ovarian neoplasms in female dogs, oestrogen-secreting tumours in intact males (Sertolioma, Sertoli cell tumour)
How does Hyperoestrogenism appear grossly?
Bilateral and symmetrical loss of hair over the trunk
What does a histological ‘flame figure’ represent?
Collagen bundle and all around it there are inflammatory cells – reaction of eosinophils
Name 3 eosinophilic diseases of cats that make up the eosinophilic granuloma complex
- Eosinophilic plaque
- Eosinophilic granuloma
- Indolent ulcer
Name 2 eosinophilic diseases of horses
- Eosinophilic granuloma
- Multisystemic eosinophilic epitheliotrophic disease (MEED)
Describe an eosinophilic plaque, its location and appearance
- Pruritic lesion associated with hypersensitivity
- Haired skin of inguinal, axillary and lateral thigh areas.
- Diffuse and perivascular eosinophilic dermatitis with epidermal acanthosis (dark discolouration) and spongiosis
Which of the 3 components of the eosinophilic granuloma complex is most common?
Eosinophilic granuloma
How does an eosinophilic granuloma appear grossly?
Raised, pink variably pruritic nodular lesions on both haired skin (linear) and oral mucosa (nodular)
How does an eosinophilic granuloma appear histologically?
- Diffuse eosinophilic inflammation with granulomas centred around degenerated collagen bundles covered with degenerate and degranulating eosinophils (flame figures)
- Localised inflammatory reaction against something that was normal – collagen
What is an indolent ulcer?
- Unilateral or bilateral ulcerated plaque-like lesion on the upper lip
- Non pruritic and non-painful
Name 3 equine eosinophilic nodular diseases
- Collagenolytic granuloma
- Axillary nodular necrosis
- Unilateral papular dermatosis
Describe the gross appearance of collagenolytic granuloma
- Single or multiple nodular, non-painful non pruritic lesions
- Nodular mass, happening everywhere in the skin
Describe the histological appearance of collagenolytic granuloma
Foci of collagen degeneration/necrosis surrounded by granulomas, sometimes with macrophage palisading, and numerous eosinophils
Describe the gross appearance of axillary nodular necrosis
Nodular non painful non pruritic lesions on the trunk, behind the axilla (girth galls)
Describe the histological appearance of axillary nodular necrosis
Foci of coagulative necrosis with numerous eosinophils and fewer flame figures (eosinophilic vasculitis may be present)
Describe the features of unilateral papular dermatosis
- Seasonal and uncommon unilateral nodules on the lateral trunk
- Small foci of folliculocentric coagulative necrosis
What are the 4 tumour classifications?
- Epithelial tumours
- Mesenchymal tumours
- Round cell tumours
- Metastatic tumours
Tumours of the epidermis derive from which cells?
Keratinocytes
Describe the features of an epidermal cyst
- Clinically recorded as single, rarely multiple, dermal masses, but not neoplastic
- Cystic cavities filled with lamellar keratin and lined by continuous squamous epithelium.
- Easy to remove and don’t regrow
What are the causes of an epidermal cyst
- Enormous abnormal distension of follicles
- Traumatic dermal implantation of epidermal fragments (more rare)
A sudden fast increase in size of an epidermal cyst is due to?
Damage to the wall of the cyst -> inflammation
Name some example tumours of the epidermis and adnexal structures
- Papilloma
- Squamous cell carcinoma
- Basal cell carcinoma
- Tumours of the hair follicles
- Sebaceous and modified sebaceous gland tumours (adenoma/ epithelioma/ carcinoma)
- Sweat gland and modified sweat gland tumours (adenoma/adenocarcinoma)
What are the two main aetiologies associated with tumours of the epidermis and adnexal structures?
UV light
Papillomavirus
Describe a cutaneous papilloma
One or multiple filiform exophytic (abnormal growth that sticks out from the surface of a tissue) and hyperkeratotic projections of epidermis supported by thin dermal stalks (proliferation and vacuolisation of stratum spinosum and granulosum)
Describe a fibropapilloma
Plaque-like lesions with predominant dermal proliferation (feline fibropapilloma and equine sarcoid)
How do papilloma’s appear histologically?
Solitary, benign and exophytic proliferation of hyperkeratotic stratified squamous epithelium supported by a mature fibrovascular stalk
What is a koilocyte?
Keratinocytes with eccentric pyknotic nucleus (irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis or apoptosis) and peripheral clear halo (ballooning degeneration)
Describe the aetiology of squamous cell carcinomas
UV lights is directly involved in the pathogenesis of these tumours in white/pale coated animals.
Viral papillomatosis can be a predisposing condition.
Why are squamous cell carcinomas hard to surgically remove?
Due to being locally invasive and the more you dig, the more you find – grows deep in the dermis
Describe the gross distribution and appearance of a squamous cell carcinoma
- Found everywhere but mainly on the head
- Single expansive hyperplastic ulcerated or nodular skin lesions
Describe the histological appearance of a squamous cell carcinoma
- Composed of squamous keratinocytes
- Invasive islands and cords of neoplastic cells within the dermis
- Anisocytosis (unequal RBC size), anisokaryosis (variation in nuclei size) and mitotic index are high
- Keratin pearls are often present
- Inflammation and pronounced desmoplasia (formation of connective tissue in response to tumors)
- Neutrophilic pustules due to abnormal keratin formation and necrosis
How are follicular tumours classified?
According to the segment of origin
Epithelial tumours of the cutaneous
adnexal structures derive from which 4 normal skin structures?
Hair follicles, sebaceous glands, apocrine (sweat) glands, and eccrine (sweat) glands
What is a pilomatricoma, which cells are they derived from?
- Solitary benign tumour, localized in the lower dermis and subcutis
- They are derived from the follicular matrix cells
Describe the appearance of a pilomatricoma
- Chalky white on cut surface, multilobulated and sometimes pigmented
- Central portion abruptly filled with “ghost cells” (pale eosinophil ic anucleated cells)
- Common mineralisation
What are the 3 types of sebaceous gland tumours?
- Adenoma
- Epithelioma
- Adenocarcinoma
Describe a sebaceous gland adenoma
Well-differentiated, with the majority sebocytes with few basaloid cells and ducts
- Any tumour originating from a glandular structure that is benign
- Well demarcated mass
Describe a sebaceous gland epithelioma
Majority of basaloid cells with few sebocytes and ducts. Intermediate degree of malignancy
Describe a sebaceous gland adenocarcinoma
- Cells, with variable degree of sebaceous differentiation.
- Irregular lobular formations
- Pleomorphism, high mitotic index
- Local infiltration -> regional lymph nodes -> lungs ?
