MORPHOLOGY OF SKIN LESIONS powerpoint dvl

morphology skin

1. MORPHOLOGY OF SKIN LESIONS DR.BHARGAVI REDDY.P DEPARTMENT OF DVL

2. Morphology of skin lesions

3. PRIMARY LESIONS MACULE : A circumscribed flat lesion (not palpable) , characterized by alteration in skin color, of any size or shape Macules are less than 1cm in size , they are sub classified as: 1.Hypopigmented and depigmented macules 2.Hyperpigmented macules 3.Erythematous macules

4. Hypopigmented Depigmentedmacules ↓ ↓ A decrease in the number of melanocytes A total absence of melanocytes Ex: pityriasis alba, pityriasis versicolor, Ex:vitiligo tuberous sclerosis, nevus depigmentosus,leprosy .

5. 2.Hyperpigmented macules : These are produced by an excess of melanocytes ( hypermelanocytosis ) or melanin ( hypermelanosis ) in the skin Hypermelanocytosis in Epidermis: lentigo simplex and lentigo maligna . Hypermelanosis in Epidermis:freckles,melasma . Hypermelanosis in Dermis: Mongolian spot , nevus of Ota,cellular blue nevus .

6. 3.Erythematous macules : increased blood flow through the skin caused by capillary dilatation produces erythematous (pink) macules. These are easily blanched by pressure (positive diascopy) Seen in drug rashes, psoriasis,viral . PAPULE : An elevated solid lesion less than 1cm in size .

7. PLAQUE: S olid plateau like elevation of the skin surface occupying a relatively large surface area in comparison with its height above the skin surface, which is grater than 1cm in size . Seen in Psoriasis Vulgaris,pityriasis rosea and Bowen’s disease .

8. Annular plaques with flat to depressed centers and raised margins are characteristic of dermatophytic infections and granuloma annulare . The presence of atrophy,depigmentation,and follicular plugging in erythematous plaques suggests a diagnosis of chronic cutaneous lupus erythematosus.

9. NODULE : A nodule is a palpable, solid, round, or ellipsoidal lesion greater than 1 cm in size. It is the depth of the lesion that differentiates a nodule from a papule or plaque. Depending on the level of the skin involved, a nodule may involve primarily the epidermis, dermis, or the subcutis . 1.Pure epidermal nodules: N odular basal cell carcinoma and keratoacanthoma . 2.Dermal nodules: Metastatic carcinoma, lymphomas, histoid leprosy, and dermatofibroma. 3.Subcutaneous nodules: Lipomas,tendinous xanthomas, and erythema nodosum . TUMOR : It is a large nodular lesion (benign or malignant ).

10. GUMMA:“ Gumma ” is term specifically used for the granulomatous nodular lesion of tertiary syphilis.

11. VESICLE and BULLA: vesicle is a circumscribed , elevated, superficial lesion containing clear fluid, less than 1cm in diameter; a vesicle larger than 1cm in diameter is called a bulla . Based on the level of split within skin —pemphigus and pemphegoid . Cleavage of T he intercellular bridges of the epidermal cells (called “ acantholysis ”)— pemphigus . In the basement membrane zone (BMZ)--- pemphegoid . Subcorneal —impetigo contagiosa and pemphigus foliaceous . S pinous layer—contact dermatitis and dyshidrotic eczema. Suprabasal in pemphigus vulgaris . D ermoepidermal junction or BMZ—bullous pemphigoid, linear IgA dermatosis , dermatitis herpetiformis . Umbilicated vesicles are characteristic of varicella infection.

12. PUSTULE : A pustule is a circumscribed, elevated lesion containing visible purulent exudates. Pus is composed of leukocytes and cellular debris and often contains bacteria. However, sterile pus is a feature of many dermatoses such as pustular psoriasis or sub corneal pustular dermatosis. Pustules are seen in impetigo, folliculitis , furuncle ,rosacea, Reiter’s disease, and halogenoderma .

13. CYST : A cyst is a sac that contains liquid or semisolid material, lined by a true epithelium.Cyst may be soft or doughy, hard, or fluctuant. The two most common cutaneous cysts are 1.Epidermal cysts (keratinous cysts), which are lined with squamous epithelium and produce keratinous material. 2.Pilar cysts , which originate from the hair follicle and are lined with a multilayered epithelium .

14. ABSCESS : An abscess is a collection of pus below the skin.an abscess is invisible but clinically can be inferred from the signs of inflammation in the overlying skin. Abscess cavities do not have a well-defined lining as cysts do.

15. PURPURA, PETECHIAE, and ECCHYMOSES: Extravasation of red blood cells in the dermis produces pin-point purpuric lesions which do not blanch (negative diascopy ). Smaller lesions (1–2 mm) are often called petechiae , whereas larger and deeper lesions are called ecchymoses . Purpuric lesions may be palpable or non palpable. Seen in senile purpura, Henoch Schonlein purpura , thrombocytopenic purpura, vasculitis, port-wine stain and pityriasis rosea .

16. WHEA L: an evanescent elevated lesion with erythema and edema frequently with central pallor,characteristic of urticaria . It results from a transient vascular reaction in the upper dermis in which there is both vasodilation and increased permeability of the capillaries giving rise to edema. The size may range from a few millimeters to morethan 10 cm. Stroking of normal skin may produce wheals in a quarter of normal individuals; this phenomenon is known as dermographism .

17. Angioedema : diffuse, deep, edematous reaction occurring in areas with loose dermis and subcutaneous tissue such as the lip,eyelids , and rarely the larynx. In contrast to wheals which are temporary, angioedema tends to persist for a longer time and is often associated with dull aching pain. Laryngeal edema may occur as a part of an anaphylactic reaction to insect stings or drugs and may be fatal because of airway obstruction .

18. SECONDARY LESIONS ATROPHY : It refers to a reduction in the components of a tissue, organ, or part of the body. In the skin, atrophy may involve the epidermis, dermis, or subcutis . Epidermal atrophy- - results from a decrease in the number of epidermal cells and presents as glossy paper-thin, and wrinkled skin with alteration or loss of normal skin markings. Dermal atrophy —clinically detectable depression of the skin. In dermal atrophy without epidermal involvement, skin color and markings remain normal in the affected area. However,dermal atrophy is usually associated with epidermal atrophy as in striae , discoid lupus erythematosus, or lichen sclerosus et atrophicus . Subcutis —deep depressions of the skin may occurs, when atrophy involves panniculus seen in progressive lipoatrophy, morphea profunda , or lupus profundus

19. EROSION : An erosion results from the loss of a part or whole of the epidermis or mucosal epithelium, but with an intact dermis or sub epithelial tissue , Hence,healing occurs without scarring unless the lesion becomes secondarily infected . Common sources of erosions: 1. Traumatic detachment of the epidermis 2.Rupture of vesiculo bullous lesions of blistering disorders such as pemphigus, toxic epidermal necrolysis, epidermolysis bullosa , or infective lesions of herpes simplex .

20. EXCORIATION : Excoriations result from scratching and are characteristically linear. They are commonly seen in pruritic disorders such as atopic dermatitis and scabies . LICHENIFICATION : It is a plaque of thickened skin with accentuated skin markings caused by constant rubbing , for example in the areas of lichen simplex chronicus .

21. ULCER An ulcer is a defect with a loss of epidermis and at least part of the dermis (upper papillary dermis) and thus, ulcers always heal with scarring. An ulcer includes margins, edges, base, floor. Ulcer margins are typically boggy in pyoderma gangrenosum . Marjolin’s ulcer —seen in post traumatic scars and old healed burns . Causes of ulcer includes—venous stasis,trauma,TB,chancroid .

22. SCAR :A scar is a visible alteration in the appearance of the skin following the proliferation of fibrous tissue in response to an injury, upto the level of the reticular . Scars may be atrophic or hypertrophic or keloidal . Atrophic scars frequently result after trauma, surgery,acne , chickenpox, herpes zoster, etc. Atrophic scars of acne may have different morphologies such as deep-pitted, rolling or boxcar like scars.

23. Exaggerated fibrous response to the healing results in the formation of keloid or hypertrophic scarring . Hypertrophic scars that remain confined within the area of primary injury, a keloid extends beyond and presents with web-like extensions .

24. SCLEROSIS: It is a circumscribed or diffuse hardening or induration of the skin easily felt than seen. Results from subcutaneous edema,infiltrations and collagen deposition. Seen in scleroderma,morphea and chronic lymphedema.

25. SCALES :an abnormal shedding or accumulation of stratum corneum visible flakes is called scaling.

26. CRUSTS Results from dried up exudates on the skin surface. Blood forming a major component of crust is called scab Thin honey colored crusts--- Impetigo Thick yellow crusts---- secondary pyoderma Adherent crusts---- Ecthyma