Term
| What signalments are important when diagnosing dermatologic disease? |
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Definition
- Age
- Congenital/hereditary conditions--> early age
- Breed
- Sex
- Reproductive hormone endocrinopathies
- Color
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Term
| What 3 derm diseases should you think of for a puppy with hairloss? |
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Definition
- Demodicosis
- Pyoderma
- Dermatophytosis
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Term
| What 3 disease should you think of for an older dog with hariloss? |
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Definition
- Endocrine disorders
- Neoplasia
- Follicular dermatoses
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Term
| What are some important history questions that should be asked when diagnosing a derm disease? |
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Definition
- Seasonal or non-seasonal?
- Which came first: itching, alopecia, or pustules?
- What is the progression of the disease?
- Any changes from when it first occured until now?
- Other animals or people affected?
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Term
| What are primary lesions? |
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Definition
- Main clinical sign that is directly caused by the disease process
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Term
| What are secondary lesions? |
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Definition
- Generally not very specific for the disease causing them
- May be caused by inflammation or self-trauma
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Term
| List the 11 types of primary lesions. |
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Definition
- Macule
- Patch
- Papule
- Plaque
- Pustule
- Vesicle
- Bulla
- Wheal
- Nodule
- Tumor
- Cysts
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Term
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Definition
- Circumscribed flat spot <1 cm
- Recognized by a change in color
- May be melanin, depigmentation, erythema, or local hemorrhage
- Cannot palpate! (doesn't feel different than normal skin)
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Term
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Definition
- A macule >1 cm in diameter
- Cannot palpate!
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Term
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Definition
- Small, raised solid elevation <1 cm
- Frequently erythematous
- May have a crust on top (ruptured pustule)
- Represents infiltraion of cells: intraepidermal, intradermal edma, or epidermal hypertrophy
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Term
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Definition
- Larger, flat-topped raised lesion
- Formed by extension or coalition of papules
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Term
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Definition
- Small circumscribed elevation of skin filled with pus
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Term
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Definition
- Circumscribed lesions <1 cm
- Filled with clear fluid
- Intraepidermal or subepiderma, rare
- Usually indicates autoimmune (small animal) or virus (large animal)
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Term
| What should you think about first if you see hemorrhagic vesicles? |
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Definition
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Term
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Definition
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Term
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Definition
- Circumscribed raised lesions consisting of edema (pits when pressed)
- Appears and disappears within minutes to hours
- Ex: hives, positive rxn to skin test
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Term
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Definition
- Solid, firm raised lesion >1 cm
- Results from massive infiltration of inflammatory or neoplastic cells into derms or subcutis
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Term
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Definition
- Neoplastic enlargement of any structure of skin
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Term
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Definition
- Epithelial-lined cavity filled with fluid or solid material (keratin, sebaceous, or apocrine secretions)
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Term
| List the 6 lesions that may be primary or secondary lesions. |
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Definition
- Alopecia
- Scale
- Follicular casts
- Hyperpigmentation
- Hypopigmentation
- Comedo (comedones)
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Term
| What is alopecia? Describe when it is a primary vs secondary lesion. |
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Definition
- Absence of hair from skin areas where it is normally present
- Primary lesion- endocrinopathies
- Secondary lesion- pyoderma, demodex, & dermatophyte
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Term
| What is scale? Describe when it is a primary vs secondary lesion. |
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Definition
- Accumulation of loose fragments of horny layer of skin (seborrhea)
- Primary lesion- cornification disorders
- Secondary lesion- self-trauma, inflammation, or infection
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Term
| What are follicular casts? Describe when this is a primary vs secondary lesion. |
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Definition
- Accumulation of keratin & follicular material that adheres to the hair shaft
- Primary lesion- any keratinization disorder (ex: primary idiopathic seborrhea)
- Secondary lesion- any disease with follicular inflammation (ex: demodicosis, pyoderma)
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Term
| What is hyperpigmentation? Describe when it is a primary vs secondary lesion. |
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Definition
- Increased epidermal & sometimes dermal melanin
- Primary lesion- hormonal disease
- Secondary lesion- inflammation (more common)
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Term
| What is hypopigmentation? Describe when it is a primary vs secondary lesion. |
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Definition
- Loss of epidermal melanin
- Primary lesion- immune-mediated disease (vitiligo)
- Secondary lesion- inflammation (more common)
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Term
| What is comedo (comedones)? Describe when this is a primary vs secondary lesion. |
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Definition
- Dilated hair follicle filled with keratin & sebaceous debris
- Primary lesion- seborrhea, primary keratinization disorder, or endocrine disease
- Secondary lesino- diseases with follicular inflammation (ex: demodicosis, pyoderma)
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Term
| What are the 10 types of secondary lesions? |
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Definition
- Epidermal collarettes
- Crust
- Scar
- Excoriation
- Erosion
- Ulcer
- Lichenification
- Hyperkeratosis
- Fissure
- Callus
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Term
| What are epidermal collarettes? |
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Definition
- Special type of scale arranged as a circular rim of loose keratin
- Footprint of a pustule
- Often indicative of a staph bacterial infection
- The most useful secondary lesion!!!
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Term
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Definition
- Dried exudate composed of serum, pus, blood, cells, scales, and/or medication on surface of skin
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Term
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Definition
- Area of fibrous tissue that has replaced the damaged dermis or subcutis
- Most are alopecic, depigmented, & atrophic
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Term
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Definition
- Linear superficial removal of epidermis by scratching, biting, or rubbing
- Most are self-induced
- Can be erosions or ulcers
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Term
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Definition
- Break in continuity of epidermis
- Does not penetrate basement membrane
- Heals without scarring
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Term
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Definition
- Deeper break in epidermis with exposure of underlying dermis
- Heals with scarring
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Term
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Definition
- Thickened, hardened skin with exaggerated superficial skin markings (resembles elephant hide)
- Results from friction and chronic inflammation
- Usually hyperpigmented
- Indicates chronicity
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Term
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Definition
- Increase in thickness of horny layer of skin
- Histologic diagnosis
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Term
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Definition
- Linear damage into epidermis, may extend into dermis
- Caused by diseaes or injury
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Term
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Definition
- Thickened, hyperkeratotic, lichenified plaque over bony prominences
- Results from pressure & chronic low-grade friction
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Term
| What is the triad of chronicity? |
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Definition
- Lichenification
- Hyperkeratosis
- Hyperpigmentation
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Term
| What should your therapeutic plan be based on? |
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Definition
- Diagnosis
- Clinical signs
- Presenting complaint
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Term
| What are the 4 main responses of the epidermis to injury? |
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Definition
- Alterations in growth or differentiation
- Alterations in fluid balace or cell adhesion
- Inflammatory lesions
- Alterations in epidermal pigment
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Term
| After injury, what 5 ways dows the epidermis alter in growth or differentiation? |
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Definition
- Hyperkeratosis
- Epidermal hyperplasia
- Dyskeratosis/Apoptosis/Necrosis
- Dysplasia
- Atrophy
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Term
| What is kyperkeratosis (path definition)? |
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Definition
- Increased thickness of the stratum corneum (keratin layer)
- Can be non-specific reaction to chronic stimuli
- 2 Types:
- Orthokeratotic hyperkeratosis
- Parakeratotic hyperkeratosis
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Term
| What is orthokeratotic hyperkeratosis? |
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Definition
- No keratinocyte nuclei in the stratum corneum
- Commonly seen with:
- Seborrhea
- Ichthyosis
- Vit A deficiency
- Pneumoic device: 'O' in the word stands for the empty space (lack of nuclei)
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Term
| What is parakeratotic hyperkeratosis? |
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Definition
- Keratinocyte nuclei are retained in the stratum corneum (nuclei are not normal here)
- Commonly seen with:
- Zinc-responsive dermatosis
- Superficial necrolytic dermatitis
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Term
| Describe a basket weave pattern of hyperkeratosis. |
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Definition
- Exaggerated undulating patterns of layers of the stratum corneum
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Term
| Describe a compact pattern of hyperkeratosis. |
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Definition
- Layers of the stratum corneum are compact
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Term
| What is epidermal hyperplasia? |
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Definition
- Increased thickness of the epidermis, usually the stratum spinosum (acanthosis)
- Often with down growths of epidermis (rete pegs) into the dermis
- Non-specific response to chronic stimuli
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Term
| What patterns of rete pegs can be used to further characterize epidermal hyperplasia? |
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Definition
- Regular
- Irregular
- Papillated
- Pseudocarcinomatous
- Note: rete pegs are normally seen in areas of high friction (foot pads, gigiva) to help withstand the friction
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Term
| What's going on in this cell? It has hypereosinophilic cytoplasm, condensed chromatin, intact cell membrane, and no inflammation. |
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Definition
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Term
| Three things can causes a cell to appear hypereosinophilic with pyknotic (shrunken/dark) nuclei. What are they? |
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Definition
- Dyskeratosis
- Apoptosis
- Necrosis
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Term
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Definition
- Premature keratinizatino of cells in the viable layers of the epidermis (i.e. not the stratum corneum)
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Term
| What usually causes dyskeratosis/apoptosis/necrosis confined to the basal layer? |
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Definition
- Discoid lupus
- Mucocutaneous pyoderma
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Term
| What usually causes multifocal dykeratosis/apoptosis/necrosis? |
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Definition
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Term
| What usually causes diffuse/full thickness dyskeratosis/apoptosis/necrosis? |
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Definition
- Toxic epidermalnecrolysis
- Thermal injury, etc
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Term
| What is an erosion (path definition)? |
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Definition
- Partial thickness loss of the epidermis
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Term
| What is an ulcer (path definition)? |
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Definition
- Full thickness loss of the epidermis
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Term
| What is epidermal dysplasia? |
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Definition
- Abnormal development of the epidermis
- Typically occurs in the basal cells
- Often a pre-neoplastic lesion
- Histologically:
- Irregular layering
- Anisocytosis (variation in cell size)
- Anisokaryosis (variation in nuclear size)
- Increased mitotic figures
- Large hyperchromic nuclei
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Term
| What is epidermal atrophy? |
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Definition
- Decrease in the number and size of cells in the epidermis
- Result of subepithelial injury
- Commonly seen with:
- Hyperadrenocorticism
- Partial ischemia
- Post-rabies vaccine panniculitis
- Severe malnutrition
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Term
| In response to injury, what are the 3 alterations in epidermal fluid balance and cellular adhesion? |
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Definition
- Edema
- Intercellular edema (spongiosis)
- Intracellular edema (ballooning/hydropic degeneration)
- Acantholysis
- Vesicles
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Term
| How does intercellular edema (spongiosis) occur? |
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Definition
- Edema from the dermis extends into the epidermis & widens the intercellular spaces, resulting in spongiosis
- As severity increases, fluid may push cells out of the way & result in the formation of spongiotic vesicles
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Term
| What can intracellular edema (ballooning/hydropic degeneration) result in? |
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Definition
- As severity of edema increases, cells can pop causing microvesicles to form in their place
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Term
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Definition
- Disruption of intercellular junctions (desmosomes) between the keratinocytes
- Often there is concurrent epidermal edema, and as the keratinocytes dissociate from each other, they becomes free-floating acantholyic cells
- Seen in the vesicles or in the crusts that form when the vesicles pop/break
- Causes:
- Immune mediated (pemphigus)
- Neutrophilic enzyme destruction (superficial bacterial folliculitis, ringworm)
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Term
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Definition
- Fluid-filled spaces in the epidermis
- Causes:
- Spongiosis
- Hydropic degeneration
- Viral infections which kill keratinocytes (ex: pox)
- Immune-mediated diseases which attack intercellular junctions causing separation of keratinocytes & formation of acantholyic cells (ex: pemphigus)
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Term
| What 2 things do ruptured vesicles result in? |
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Definition
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Term
| What causes inflammation of the epidermis, and what 2 lesions can result? |
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Definition
- Exocytosis- migration of leukoctyes into the epidermis
- Usually accompanied by spongiosis (intercellular edema)
- 2 Lesions:
- Pustules
- Crusts
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Term
| What is a pustule (path definition)? |
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Definition
- Accumulations of inflammatory cells within the epidermis
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Term
| What does the presence neutrophilic pustules suggest? |
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Definition
- Superficial bacterial infection
- Neutrophils with this are often degenerate
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Term
| What does the presence of eosinophilic pustules suggest? |
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Definition
- Ectoparasite hypersensitivity
- Pemphigus follaceous
- Feline eosinophilic granuloma complex
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Term
| What are crusts (path definition) |
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Definition
- Composed of dried fluid & cellular debris on the epidermal surface
- Form as pustules dry up or are pushed off by the hyperplastic epidermis
- Indicate previous/ongoing inflammation
- Can help make the diagnosis:
- Ex: acantholytic cells in the crust --> pemphigus
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Term
| What 2 lesions are caused by alterations in epidermal pigmentation (in response to injury)? |
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Definition
- Hyperpigmentation
- Pigmentary incotinence
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Term
| What is hyperpigmentation due to? |
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Definition
- Increased production of melanin by existing melanocytes (more common)
- Chronic inflammatory disease (ex: allergic dermatitis)
- Endocrine dermatoses (ex: hyperadrenocorticism)
- Due to proliferation of melanocytes (less common)
- Ex: Lentigo (black spots around orange cats' eyes)
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Term
| What is pigmentary incontinence? |
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Definition
- Loss of melanin from the pigmented cells in the basal layer (usually due to cell damage)
- Pigment is phagocytosed by macrophages in the superficial dermis
- Causes:
- Non-specific, associated with inflammation
- Specific damage to basal cells or melanocytes
- Lupus
- Mucocutaneous pyoderma
- Uveodermatologic syndrome
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Term
| What are the 4 responses of the dermis to injury? |
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Definition
- Alterations in growth
- Collagen degeneration
- Dermal deposits
- Inflammation in the dermis
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Term
| What are the 2 alterations of growth of the dermis that can happen in response to injury? |
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Definition
- Dermal atrophy
- Solar elastosis
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Term
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Definition
- Decrease in the quantity of collagen fibrils & fibroblasts in the dermis
- Usually a result of a catabolic state with excessive protein degeneration (hyperadrenocorticism, starvation)
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Term
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Definition
- Increased numbers of thick, interwoven basophilic elastic fibers in the superficial dermis
- Due to chronic UV exposure
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Term
| What is collagen degeneration? |
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Definition
- Collagen is surrounded by eosinophils & major basic protein, making it appear hyper-eosinophilic (flame figures)
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Term
| What are 3 types of dermal deposits? |
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Definition
- Amyloid
- Plasma cell tumors, dermatomyositis
- Mucin
- Normal in Shar-Peis
- Hypothyroidism
- Calcium
- Dystrophic or metastatic
- Calcinosis cutis (hyperadrenocoriticism), calcinosis circumscripta (pressure points)
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Term
| What are the 4 patterns of inflammation in the dermis? |
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Definition
- Perivascular
- Vasculitis
- Interface
- Nodular/diffuse
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Term
| What is pervascular dermatitis? |
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Definition
- Inflammatory cells are centered around the blood vessels
- Usually superficial (invovlement of both superficial & deep dermis suggests systemic disease)
- Least specific pattern
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Term
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Definition
- Inflammation targeting the walls of the blood vessels, resulting in damage to the vessel wall
- Results in ischemia
- Can be immune-mediated (type 3) or septic
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Term
| What is interface dermatitis? |
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Definition
- Superficial dermal inflammation with inflammatory cells surrounding the dermo-epidermal (D-E) junction
- Cell poor
- Cell rich (lichenoid)
- Causes damage to the basal cells
- Vacuolated (hydropic degeneration) or necrotic/apoptotic
- Often pigmentary incontinence as the basal cells leak pigment into the superficial dermis
- Combo of basal cell changes & inflammation obscures the D-E junction
- Think immune-mediated
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Term
| What is nodular to diffuse dermatitis? |
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Definition
- Characterized by nodules or diffuse sheet-like infiltrates of inflammatory cells in the dermis or subcutis
- Usually infectious (can be sterile)
- Type of cells indicates pathogenesis
- Neutrophils --> bacteria
- Granulomatous --> fungal (or foreign body)
- Eosinophils --> parasites
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Term
| What are the 2 responses of the adnexa to injury? |
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Definition
- Alterations in growth
- Inflammation of the adnexa
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Term
| What are the 2 alterations in growth of the adnexa in response to injury? |
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Definition
- Atrophy
- Primarily telogen hair follicles & other adnexa
- Causes:
- Endocrine disease (hyothydroidism, hyperadrenocorticism)
- Ischemia (traction alopecis of poodles)
- Hypertrophy
- Primarily anagen follicles
- 2ndary to repeated trauma (ex: acral lick dermatitis)
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Term
| What are 3 types of inflammation of the adnexa in response to injury? |
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Definition
- Folliculitis
- Furunculosis
- Sebaceous adenitis
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Term
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Definition
- Inflammation of a hair follicle
- Usually infectious
- Mural folliculitis- in & around follicle wall
- Luminal folliculitis- within the follicular lumen
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Term
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Definition
- Inflammatory reaction that occurs following follicular rupture & extrusion of hair & keratin into the dermis
- Leads to granulomatous inflammation
- Very common
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Term
| What is sebaceous adenitits? |
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Definition
- Immune-mediated reaction targeting the sebaceous glands
- Can result in total loss of the glands
- Seen in Akitas, Std. Poodles, & Vizlas
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Term
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Definition
- Inflammation of the subcutaneous adipose tissue
- Causes:
- Infectious (bacteria, mycobacteria, fungi)
- Immune-mediated (lupus)
- Nutritional (Vit E deficiency)
- Pancreatic disease (pancreatitis, pancreatic carcinoma)
- Idiopathic
- Vaccine/Injection reaction
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