THE SKIN

Salvatore Mangione, MD

"The power of making a correct diagnosis is the key to all success in the treatment of skin diseases; without this faculty, the physician can never be a thorough dermatologist, and therapeutics at once cease to hold their proper position, and become empirical." -Louis A. Duhring (1845-1913)

"Beautys but skin deep."

-John Davies of Hereford (1565-1618)

BASIC TERMINOLOGY AND DIAGNOSTIC TECHNIQUES

1. How many skin diseases exist? What are the two main categories of skin lesions? There are more than 1400 skin diseases. Yet, only 30 are important, common, and worth knowing. The first step toward their recognition is the separation of primary from secondary lesions (Table 3-1). • Primary lesions result only from disease and have not been changed by additional events (such as trauma, scratching, or medical treatment; see Table 3-1). To better identity primary lesions, pay attention to their colors, shape, arrangement, and distribution. • Secondary lesions instead have been altered by outside manipulation, medical treatment, or their own natural course.

2. What are the major primary lesions? • Hanel's: Flat, nonpalpable, circumscribed areas of discoloration cm in diameter. Typical macules are the familiar freckles.

• Patches: flat, nonpalpable areas of skin discoloration >0.5 cm in diameter (i.e., a large macula). A typical patch is the one of yitillgo.

• Papules: Raised and palpable lesions <0.5 cm in diameter. They may or may not have a different color from the surrounding skin. A typical papule is a raised nevus.

>0.5 are

0.5 cm

• Plaques: Raised and palpable lesions >0.5 cm in diameter (i.e., a large papule). Usually confined to the superficial dermis, they may result from the confluence of papules. A typical plaque is that of psoriasis.

• Nodules: Raised, palpable, and elevated lesions >0.5 cm in diameter, which, unlike plaques, go deeper into the dermis. Since they are below the surface of the skin, the overlying cubs is usually mobile. Typical nodules are those of erythema nodosum.

• Tumors: Nodules that are either >2 cm in diameter or poorly demarcated. Usually neoplastic.

• Wheals (hives): Raised, circumscribed, edematous, and typically pruritic plaques that are pink or pale but typically transient. Classic wheals are the lesions of urticaria, or of a mosquito bite.

• Vesicles (blisters): Fluid-filled, circumscribed, and raised lesions that contain clear serous fluid and are cm in diameter. Typical vesicles are those of herpes simplex.

• Bullae: Vesicles >0.5 cm in diameter. Commonly seen in patients with second-degree burns. Presence of a Ruda is so important that it usually trumps all other concomitant primary lesions.

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• Cysts: Raised and encapsulated lesions that contain fluid or semi-solid material. Typical are the cysts of acne.

• Pustules: Pus-tilled papules. Typically seen in patients with impetigo or acne.

• Purpura: Skin extravasation of red cells, which, based on size, may present as petechiae or ecchymoses. Palpable purpura is never normal and argues for an antigen-antibody complex (vasculitis). Often localized to the lower extremities, the lesions of Henoch-SchOnlein are typical examples of a palpable purpura. Internal organs (kidneys, GI tract) are often involved too.

• Petechiae: Reddish-to-purple discoloration, caused by a microscopic hemorrhage. These are <0.5 cm in diameter and usually in clusters. With the exception of color, they resemble papules or /mules (depending on whether they are palpable or not). Typical petechiae are those of typhus. The lesions of thrombocytopenic thrombotic purpura (TTP) are typical petechiae too.

• Ecchymoses (bruises): Reddish-to-purple discoloration larger than petechiae. Except for color, they resemble plaques and patches (depending on whether they are palpable or not). Typically located below en intact epithelial surface

• Spider anginas: These are arterial teleangiectasias, i.e., vascular arterial lesions that resemble the legs of a spider. They fill from Milirid blanch whenever this is

• Venous spiders: These are venous teleangiectasias, i.e., vascular venous lesions that also resemble the legs of a spider. Hence, they fill from the periphery, not the center. They empty with pressure.

(Figures adapted tram Willms JL, Schneiderman H, Morena PS: Physical Deg.". Bellmore, Williams 8 Wilkins, 1994, with perrussion.)

3. What are the major secondary lesions? • Excoriation: Linear erosions produced by scratching. Often raised, scratch marks may also present as crust on top of a primary lesion that has been partially scratched off. They are almost exclusively confined to the eczematous diseases.

• Lichenification: A typical skin thickening seen in chronic pruritus with recurrent scratching. Resembles the callus formation of palms and soles after recurrent trauma. Lichenified skin is hardened, leather-like, with prominent markings and some scaling. Like excoriation, lichenification is typical of eczematous diseases. In fact, it is considered pathognomonic of atonic dermatitis.

• Scales: Raised lesions presenting as flaking of the upper skin surface. In fact, they represent thickening of the stratum corneum, the uppermost layer et the epidermis. Scales may be white, gray, or tan. They may also be small or rather large. They provide the swarms component to paoulosguamous diseases. They am extremely common in the scalp, where they suggest either banal processes (dandruff) or more serious conditions (seborrheic dermatitis, psoriasis, and tinea capitis)

• Crusts: Raised lesions produced by dried serum and blood cell remnants. Usually preceded by fluid-fined primary lesions (i.e., vesicles, pustules, or bullae). The most familiar crust is the "scab" of impetigo.

• Erosions: Depressed lesions produced whenever the epidermis is either removed or sloughed. They are moist, usually red, and well circumscribed. Classic erosions are those of chickenpox following rupture of a vesicle.

• Ulcers: Depressed lesions produced whenever not only the epidermis but also part (or all) of the dermis is gone. Ulcers are concave, often moist, and at times inflamed or even hemorrhagic. They heal with scarring. a classic ulcer is that of the syphilitic chancre.

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• Fissures: Depressed lesions presenting as narrow, linear, and vertical cracks that penetrate through the epidermis, reaching at least part of the dermis. Classic fissures are o1 the athlete's toot.

• Atrophy: Usually the nonspecific end-product of various skin disorders. It is characterized by a pale and

shiny area, with loss of cutaneous markings and full skin thickness.

• Sinuses: Connective channels between the surface of the skin and deeper components.

ry -

Fissure

Atrophy

(Figures from Fitzpatrick JE, Aeling JL: Dermatology Secrets. Philadelphia, Hanley & Bens, 1996, with Permission.)

4. Are there other ways to classify Skin lesions? Many ways. One divides lesions into four groups based on the relationship with the surrounding skin: • Flat, nonpalpable: Macule, patch, purpura, ecchymosis, spider angioma, venous spider • Raised, solid, palpable: Papule, plaque, nodule, tumor, wheal, scale, crust • Raised, cystic, palpable: Vesicle, pustule, bulla, cyst • Depressed: Atrophy, erosion, ulcer, fissure 5. What is the pattern of distribution? Beside the distribution in the body (i.e., generalized versus localized), this descriptor refers to the relationship of lesions to one another • Clustered (grouped, herpetiform) lesions are in close proximity, occurring in a group or series of groups. • Confluent (coalescent) lesions are multiple and blending together. • Dermatemal lesions are typically distributed along neurocutaneous dermatomes. Like herpes zoster (shingles). 6. What is the configuration of a skin lesion? It is the outline of the lesion as observed from above. The most common configurations are: • Annular: Doughnut-shaped lesions. Fungal infections present as and rings with the scaly surface. • Linear: Lesions arranged in a line. For example, streaks of small vesicles on an erythematous base. The most common linear lesion is the rash of poison ivy, also called rhus dermatitis ghus is the Greek word for sumac, which describes various shrubs or small trees). Some species of sumac, or rhus, include poison ivy and poison oak-both cause an acute itching rash on contact. • Reticular: Lesions organized in a net-like cluster • Gyrate: Lesions with a serpiginous (or polycyclic) configuration-as in gyrate erythema 7. How should an initial cutaneous exam be done? From head to toe. Patients should fully disrobe, sothat the entire body can be inspected-including palms, soles, scalp, and mouth. If a total skin exam is not feasible, a targeted exam of lesions, as guided by history, is also appropriate. Either way, always attempt to complete at least an upper body exam, since the trunk represents a large but easily examinable surface area.

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