(Modul 2) Lesion Description & Distribution [PDF]

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Modul 2



Drh. Herisman Hernadi Resident of AiCVD Veterinary Dermatology Practitioner Founder of AVDI



LESION DESCRIPTION & DISTRIBUTION



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References



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Lesion Description



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MORPHOLOGY OF SKIN LESIONS



• The morphologic characteristics of skin lesions → an essential feature of dermatologic diagnosis • The clinician must learn to recognize primary and secondary lesion • Primary lesion is the initial eruption that develops spontaneously as a direct reflection of underlying disease. • Secondary lesions evolve from primary lesions or are artifacts induced by the patient or by external factors such as trauma and medications Sponsored By:



Primary Lesions



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Primary Lesions



• Macule • Patch • Papule • Plaque • Pustule



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• Vesicle • Bulla • Wheal • Nodule • Cyst • Tumor



Macule & Patch



Definition: Macule : Circumscribed flat area of color change < 1 cm diameter Patch : Circumscribed flat area of color change > 1 cm diameter



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Differential diagnoses: Depigmentation: vitiligo, discoid lupus erythematosus, uveodermatologic syndrome, mucocutaneous pyoderma Hyperpigmentation: lentigo, pigmented nevi, post inflammatory Erythema: inflammation Hemorrhage: trauma, vasculitis, vasculopathy, coagulopathy



Papule & Plaque



Definition : Papule : Solid elevated lesion < 1 cm diameter Plaque : Flat elevation in skin > 1 cm diameter Sponsored By:



Differential diagnoses: Papule : Allergic reaction, reaction to ectoparasites, early stage of bacterial infection, immunemediated disease, drug eruption Plaque : Chronic inflammatory disease



Pustule



Definition: Circumscribed elevation of skin containing pus; may be intraepidermal, subepidermal, or follicular in location Sponsored By:



Differential diagnoses neutrophils: Pyoderma, impetigo, folliculitis, pemphigus complex, ectoparasites, subcorneal pustular dermatosis, sterile eosinophilic pustulosis



Vesicle & Bulla



Definition: Vesicle : Sharply circumscribed elevation of epidermis filled with clear fluid, < 1 cm diameter, intraepidermal or subepidermal. Bulla : Sharply circumscribed elevation of epidermis filled with clear fluid, > 1 cm diameter. Sponsored By:



Differential diagnoses: Viral, immune-mediated diseases, irritants



Wheal



Definition: Sharply circumscribed raised lesion consisting of edema



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Differential diagnoses: Urticaria, insect bites, and positive reactions to allergy skin tests



Nodule



Definition: A circumscribed, solid elevation more than 1 cm in diameter that extends into deeper layers of the skin.



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Differential diagnoses: Sterile granulomatous diseases, bacterial or fungal infections, neoplastic diseases, calcinosis cutis



Cyst



Definition: Epithelium-lined cavity containing fluid or a solid material. It is a smooth, well-circumscribed, fluctuant to solid mass. Differential diagnoses: Usually originate from hair follicles or other adnexal structures.



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Tumor



Definition: A large mass involving skin or subcutaneous tissue.



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Differential diagnoses: Sterile granulomatous diseases, bacterial or fungal infections, neoplastic diseases.



Primary or Secondary Lesions



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Primary or Secondary Lesions



• Alopecia • Scale • Crust • Follicular Cast • Comedo • Pigmentary abnormalities Sponsored By:



Alopecia



Definition: Partial to complete loss of hair. Differential diagnoses: Primary: endocrine diseases (hypothyroidism, hypercortisolism), follicular dysplasia, telogen effluvium, anagen defluxion Secondary: pruritus, bacterial folliculitis, dermatophytosis, demodicosis



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Scale



Definition: Accumulation of loose fragments of horny layer of skin (cornified cells); may appear branny, fine, powdery, flaky, platelike, greasy, dry, loose, adhering, or nitlike. Color varies from white, silver, yellow, or brown to gray Sponsored By:



Differential diagnoses: Primary lesions: primary idiopathic seborrhea, ichthyosis, some cases of follicular dysplasia Secondary lesions: chronic inflammation



Crust



Definition: Accumulation of dried exudate, serum, pus, blood, cells, scales, or medications adherent to skin surface



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Differential diagnoses : Crust may be primary as in primary seborrhea, superficial necrolytic dermatitis, and zinc responsive dermatosis, or secondary as in pyoderma, fly strike, or pruritus. Hemorrhagic crusts in pyoderma are brown or dark red; yellowish green crusts appear in some cases of pyoderma; tan, lightly adhering crusts are found in impetigo. Vegetations are heaped-up crusts (seen in pemphigus vegetans). Dark crusts imply deeper tissue damage or hemorrhage and may be seen more with traumatic wounds, furunculosis, fly strike dermatitis, and vasculitis. Honey-colored crusts are more commonly infectious in nature; thicker dry yellow crusts are more typical of scabies and zinc-responsive dermatosis. Tightly adherent crusts are typical in zinc-responsive dermatosis and necrolytic migratory erythema, and also occur in some cases of seborrhea



Follicular Cast



Definition : Accumulation of keratin and follicular material that adheres to hair shaft extending above surface of follicular ostia Sponsored By:



Differential diagnoses : Primary lesion in vitamin A responsive dermatosis, idiopathic seborrhea. and sebaceous adenitis. Secondary lesion in dermatophytosis and demodicosis.



Comedo



Definition : Dilated hair follicle filled with cornified cells and sebaceous material



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Differential diagnoses: Primary: feline acne, vitamin A–responsive dermatosis, Schnauzer comedo syndrome, endocrine dermatoses, congenital hypotrichosis (e.g. Chinese crested dogs) and some idiopathic seborrhea disorders. Secondary: demodicosis, dermatophytosis



Pigmentary Abnormalities



• Changes in skin coloration caused by a variety of pigments



Hyperpigmentation Sponsored By:



Hypopigmentation



Pigmentary Abnormalities Differential Diagnoses • Hypopigmentation (hypomelanosis), loss of epidermal melanin, may be primary, as with vitiligolike disease, or secondary, as in postinflammatory change. • Leukoderma is a general term for white skin, whereas vitiligo refers to a specific disease. • Lack of pigment in hair is called leukotrichia or achromotrichia.



• Hyperpigmentation (hypermelanosis, melanoderma), increased epidermal and occasionally dermal melanin. • Melanophages may be found in superficial dermis (post inflammatory, chronic, traumatic, and endocrine skin lesions). • Endocrine hyperpigmentation tends to be diffuse, whereas post inflammatory hyperpigmentation has a latticework appearance. • Excess pigment in hair is called melanotrichia



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Secondary Lesions



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Secondary Lesions



• Epidermal Collarette • Scar • Excoriation • Erosion



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• Ulcer • Fissure • Lichenification • Callus



Epidermal Collarette



Definition: Special type of scale arranged in a circular rim of loose keratin flakes or peeling keratin



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Differential diagnoses: Bacterial pyoderma, immune-mediated diseases, less often fungal, insect-bite reactions, or allergic diseases



Erosion



Definition: Shallow epidermal defect that does not penetrate basal laminar zone



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Differential diagnoses: Ectoparasites, allergies, and other causes of pruritus, immune-mediated diseases, trauma



Ulcer



Definition: Break in continuity of epidermis, with exposure of underlying dermis



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Differential diagnoses: Feline indolent ulcer, severe deep pyoderma, vasculitis, immunemediated diseases, necrolytic diseases



Lichenification



Definition: Thickening and hardening of skin characterized by exaggeration of superficial skin markings. Often hyperpigmented. Hyperkeratosis is increased thickness of stratum corneum. Sponsored By:



Differential diagnoses: Crusted lichenified plaques usually have a bacterial component and improve with antibiotic therapy. Occasionally, Malassezia are found with these lesions. Examples are the axillae in acanthosis nigricans, intertrigo, chronic allergies, and keratinization disorders



Scar



Definition : Area of fibrous tissue that has replaced damaged dermis or subcutaneous tissue Differential diagnoses: Prior trauma or skin lesions (ulcers, burns)



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Excoriation



Definition : Erosion or ulcer caused by scratching, biting, or rubbing



Differential diagnoses: Ectoparasites, allergies, irritants, and other causes of pruritus



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Fissure



Definition : Linear cleavage into epidermis, or through epidermis into the dermis, caused by disease or injury. May be single or multiple, curved, branching, or straight.



Differential diagnoses: Chronic skin diseases, canine distemper, zincresponsive dermatoses, other keratinization disorders



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Callus



Definition : Thickened, rough, hyperkeratotic, alopecic, often lichenified plaque Differential diagnoses: Elbows, hocks, hips, and sternum are commonly affected areas



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Lesions Distribution



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Lesion Distribution



• One of the most important clinical features used to prioritizing the differential diagnosis list • Some typical distribution of lesions include : • Local • Multifocal or generalized → multiple discrete regions affected such as head, feet, and ventral abdomen • Symmetric → reflect an internal cause (for example, allergies or an endocrine, metabolic, or immune-mediated disease) • Asymmetric → usually a result of infections, certain ectoparasites, or neoplasia. Sponsored By:



Lesion Distribution



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Distribution of lesions in various skin diseases



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Flea Bite Hypersensitivity



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Cheyletiellosis



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Scabies



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Notoedric mange



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Malassezia dermatitis



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Atopic Dermatitis



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Contact Dermatitis



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Epitheliotropic Lymphoma



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Miliary Dermatitis



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Symmetrical Alopecia



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Hypothyroidsm



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CONFIGURATION OF LESIONS Helpful in establishing a differential diagnosis



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Configuration of skin lesions



1. Annular → clear or less involved center and is found in superficial spreading bacterial folliculitis, local seborrhea, demodicosis, and dermatophytosis. 2. Single → typified by feline acne, acral lick dermatitis, cysts, and many tumors. 3. Polycyclic → result from confluence of lesions or spreading process. Examples are superficial spreading bacterial folliculitis, demodicosis, or pyotraumatic dermatitis. 4. Grouped → clusters, often the result of new foci developing around an old lesion. They are seen in folliculitis, insect bites, contact dermatitis, and calcinosis cutis. Sponsored By:



Configuration of skin lesions



5. Serpiginous → result of spreading, such as in canine scabies or demodicosis. They may also be due to confluence and partial resolution of polycyclic lesions. 6. Linear → form of eosinophilic granuloma of cats or by contact with irritant materials streaked along skin. 7. Arciform → result from partial resolution of polycyclic lesions such as spreading folliculitis, but they may result from spreading, as in canine scabies and demodicosis. 8. Central-healing (target) → produced when skin heals behind an advancing front of a disease process. It is typical of certain dermatophytoses, demodicosis, and bacterial folliculitis



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Q&A



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