Dermatology

Approach

병변 익히기(병소 파악, 패턴, systemic problem 등), DDx list 작성, 기본 검사법 익히기, 치료 반응 확인, 보호자 교육

History taking

Pruritus : distribution, severity, relative lesions ex) 모낭충증은 보통 가렵지 않으나, 피부 종양은 가려움.

Lesion distribution : regional, multi-regional, generalized, symmetrical, non-symmetrical

*ringworm의 경우, 보호자도 같이 걸리는 경우 있음.

PE

Lesion recognition : primary/secondary, appearance, distribution

whole body, hair coat, skin surface, pruritus, smell

*Pruritus visual analog scale(PVAS) : 보호자에게 점수를 매기게 함.

Morphology

Primary vs Secondary

Primary lesions : initial eruption that develops spontaneously as a direct reflection of underlying dz. Primary lesions(pustules, vesicles, papules) may appear quickly and then disappear rapidly.

Secondary lesions : evolve from primary lesions or are artifacts induced by the patient or by the external factors such as trauma and medications.

However, primary lesions may leave behind secondary lesions(eg. focal alopecia, epidermal collarettes, scaling, hyperpigmentation, crusts) that may be more chronic and give clues about the presence of previous primary lesions. Therefore, identification and characterization of both primary and secondary lesions are important.

Primary lesions

Macule(반점)

macule <1cm; patch(반) >1cm

Lentigo : macule+patch

Erythema(홍반)

dermal vasodilation causing redness of the skin

Diascopy - 슬라이드 글라스로 눌렀을 때 색깔 변함.

Papule(구진)

small, solid, elevated lesions up to 1cm in diameter associated w/ cell infiltration

superficial folliculitis, scabies, flea bites

Plaque(판) : a flat, solid, elevated lesion of more than 1cm in diameter, again associated w/ cell infiltration and/or proliferation

Pustule(농포) : small circumscribed skin elevation containing purulent material. This consists of degenerate inflammatory cells(most commonly neutrophils) w/ or w/o microbes or other cells(eg. acanthocytes in pemphigus foliaceus)

Bulla(대수포) & Vesicle(수포)

bulla >1cm; vesicle <1cm

occur in viral or autoimmune dermatoses, or in dermatitis caused by irritants.

Wheal(구반)

a sharply circumscribed, raised lesion consisting of edema that usually appears and disappears within minutes or hours

usually produce no changes in appearance of overlying skin and haircoat. Wheals are characteristically white to pink elevated ridges or round edematous swellings that only rarely have pseudopods at their periphery.

They blanch on diascopy. A huge hive of distensible region such as lips or eyelids is called angioedema.

Nodule(결절) : solid elevation of the skin greater than 1cm in diameter, again associated w/ cell infiltration and/or proliferation. Nodules usually result from massive infiltration of inflammatory or neoplastic cells into dermis or subcutis. Deposition of fibrin or crystalline material also produces nodules.

Cyst(낭) : enclosed cavity w/ a membranous lining that contains liquid or semi-solid matter

Primary or Secondary lesions

Alopecia(탈모)

loss of hair and may vary from partial to complete

It may be primary, such as alopecia w/ endocrine disorders and follicular dysplasia, or it can occur secondary to trauma or inflammation.

hypotrichosis, defluxion/effluvium, easy epilation

Scale(인설)

Crust(가피)

an accumulation of loose fragments of the horny layer of the skin. The corneocyte is the final product of epidermal keratinization.

may be primary lesion in some cases of color dilution alopecia, follicular dysplasia, primary idiopathic seborrhea, and ichthyosis.

common secondary lesions in chronic inflammation

composed of cells and dried exudates. It may be serous, sanguineous, purulent, or mixed.

Dark crusts : hemorrhagic, traumatic, furunculosis

Honey-colored crusts : infectious

Thicker dry yellow crusts : scabies, zinc-responsive

Tightly adherent crusts : zinc-responsitve dermatosis, necrolytic migratory erythema, seborrhea

Follicular cast : accumulation of keratin and follicular material that adheres to hair shaft extending above surface of foliicular ostia

Comedone(면포) : the result of sebaceous and epidermal debris blocking a follicle. They may be seen in many dz, but are often very prominent in cases of hyperadrenocorticism.

Pigmentary abnormalities eg. lentigo, vitiligo

Secondary lesions

Epidermal collarette : special type of scale arranged in a circular rim of loose keratin flakes or peeling keratin

Scar(반흔) : result from the abnormal fibrous tissue that replaces normal tissue after an injury, such as a burn

Excoriation(표피 박리) : result from self-trauma. In some cases, often in cats, the damage can be extensive.

Erosion(미란) : occurs following loss of the superficial part of the epidermis. Erosions heal w/o scar formation.

Ulcer(궤양) : deeper than an erosion. They occur following loss of the epidermis and basement membrane and exposure of the deeper tissue of the dermis. Lesions may scar.

Fissure

a linear cleavage into epidermis or through epidermis into dermis caused by dz or injury

may be single or multiple tiny cracks or large several centimeters long.

They have sharply defined margins and may be dry or moist and straight, curved, or branching. They occur when skin is thick and inelastic and then subjected to sudden swelling from inflammation or trauma, especially in regions of frequent movement. Examples are found at ear margins, and at ocular, nasal, oral, and anal mucocutaneous borders.

Lichenification(태선화) : occurs following chronic inflammation. There is thickening of the skin associated w/ accentuation of normal skin markings.