Approach to the Patient with a Skin Disorder¶
Chapter 59 | Harrison's 22e · Part 2 – Cardinal Manifestations & Presentation · Chapter 59
Key Clinical Points¶
- Distinguishing normal from abnormal findings is critical for identifying significant skin disease.
- Primary lesions (macule, papule, plaque, etc.) are the fundamental building blocks of dermatologic description.
- Secondary lesions (scale, crust, erosion, etc.) indicate the progression or reaction of the skin to a primary process.
- Morphological descriptors (e.g., annular, herpetiform) provide essential clues for narrowing differential diagnoses.
- Specific clinical patterns like 'target' lesions (Erythema multiforme) or 'angular purpuric patches' (Meningococcemia) are high-yield indicators of systemic disease.
- Topographical distribution is a key diagnostic tool to correlate location with specific conditions like Tinea cruris or Stasis dermatitis.
DEFINITION & CLASSIFICATION¶
• Primary Skin Lesions: The fundamental building blocks of dermatologic description. ◦ Macule: A flat, colored lesion, <2 cm in diameter, not raised above the surface of the surrounding skin. (e.g., a "freckle" or ephelid). ◦ Patch: A large (>2 cm) flat lesion with a color different from the surrounding skin; differs from a macule only in size. ◦ Papule: A small, solid lesion, <0.5 cm in diameter, raised above the surface of the surrounding skin and thus palpable (e.g., a closed comedone or whitehead). ◦ Nodule: A larger (0.5–5.0 cm) firm lesion raised above the surface of the surrounding skin; differs from a papule only in size. ◦ Tumor: A solid, raised growth >5 cm in diameter. ◦ Plaque: A large (>1 cm), flat-topped, raised lesion; edges may be distinct (e.g., psoriasis) or gradually blend with surrounding skin (e.g., eczematous).
• Secondary Skin Lesions: Changes resulting from inflammation, trauma, or infection. ◦ Lichenification: A distinctive thickening of the skin characterized by accentuated skinfold markings. ◦ Scale: Excessive accumulation of stratum corneum. ◦ Crust: Dried exudate of body fluids; may be yellow (serous) or red (hemorrhagic). ◦ Erosion: Loss of epidermis without an associated loss of dermis. ◦ Ulcer: Loss of epidermis and at least a portion of the underlying dermis. ◦ Excoriation: Linear, angular erosions that may be covered by crust and are caused by scratching. ◦ Atrophy: An acquired loss of substance; may appear as a depression with intact epidermis (loss of dermal/subcutaneous tissue) or as sites of shiny, delicate, wrinkled lesions (epidermal atrophy). ◦ Scar: A change in the skin secondary to trauma or inflammation; appearance varies based on age.
CLINICAL FEATURES¶
• Common Dermatologic Terms: ◦ Alopecia: Hair loss, partial or complete. ◦ Annular: Ring-shaped. ◦ Cyst: A soft, raised, encapsulated lesion filled with semisolid or liquid contents. ◦ Herpetiform: In a grouped configuration. ◦ Lichenoid eruption: Violaceous to purple, polygonal lesions resembling those seen in lichen planus. ◦ Milia: Small, firm, white papules filled with keratin. ◦ Morbilliform rash: Generalized, small erythematous macules and/or papules resembling lesions seen in measles. ◦ Nummular: Coin-shaped. ◦ Poikiloderma: Skin that displays variegated pigmentation, atrophy, and telangiectasias. ◦ Polycyclic lesions: A configuration of skin lesions formed from coalescing rings or incomplete rings.
• Common Clinical Conditions (Table 59-4): ◦ Acne vulgaris: Face, upper back, chest; open and closed comedones, erythematous papules, pustules, cysts. ◦ Seborrheic keratosis: Trunk, face, extremities; brown plaques with adherent, greasy scale; "stuck on" appearance. ◦ Rosacea: Blush area of cheeks, nose, forehead, chin; erythema, telangiectasias, papules, pustules. ◦ Folliculitis: Any hair-bearing area; follicular pustules. ◦ Seborrheic dermatitis: Scalp, eyebrows, perinasal areas; erythema with greasy yellow-brown scale. ◦ Herpes simplex: Lips, genitalia; grouped vesicles progressing to crusted erosions. ◦ Atopic dermatitis: Antecubital and popliteal fossae; patches and plaques of erythema, scaling, and lichenification; pruritus. ◦ Herpes zoster: Dermatomal, usually trunk (but may be anywhere); painful vesicles limited to a dermatome. ◦ Stasis dermatitis: Ankles, lower legs over medial malleoli; patches of erythema and scaling on background of hyperpigmentation with signs of venous insufficiency. ◦ Varicella: Face, trunk; lesions in crops progressing from erythematous macules → papules → vesicles → pustules → crusted sites. ◦ Allergic contact dermatitis: Anywhere; localized erythema, vesicles, scale, and pruritus (e.g., nickel on fingers/earlobes; poison ivy). ◦ Tinea versicolor: Chest, back, abdomen; scaly hyper- or hypopigmented macules. ◦ Psoriasis: Elbows, knees, scalp, lower back, fingernails; papules and plaques covered with silvery scale; nails may have pits. ◦ Candidiasis: Groin, beneath breasts, vagina, oral cavity. ◦ Dermatophytosis: Feet, groin, beard, or scalp; varies by site (e.g., tinea corporis—scaly annular plaque). ◦ Scabies: Groin, axillae, between fingers and toes, beneath breasts. ◦ Melasma: Forehead, cheeks, temples, upper lip; tan to brown patches. ◦ Cherry angioma: Anywhere; small red papules. ◦ Keloid: Site of previous injury; firm raised growth. ◦ Dermatofibroma: Anywhere; firm nodule. ◦ Insect bites: Anywhere; erythematous papules with central puncta.
DIAGNOSTIC APPROACH¶
- Observation of Morphology: Identify primary lesions (e.g., macule, papule, plaque) and secondary changes (e.g., scale, crust, lichenification).
- Assessment of Distribution: Correlate the location of findings with known patterns (e.g., "blush area" for Rosacea; "extensor surfaces" for Dermatitis herpetiformis; "dermatomal" for Herpes zoster).
- Identification of Specific Patterns: Recognize high-yield clinical markers → specific diagnosis. ◦ Target or iris morphology → Erythema multiforme (often hypersensitivity to drugs like sulfonamides or infections such as HSV). ◦ Angular purpuric patches → Fulminant meningococcemia (indicator of DIC and capillary leakage). ◦ Palpable purpuric papules → Necrotizing vasculitis.
- Differentiation: Distinguish significant findings from trivial conditions. ◦ Melanoma Screening: Evaluate for asymmetry, border irregularity, color variegation (black, blue, brown, pink, white), diameter >6 mm, and history of change (e.g., pruritus or pain).
KEY PEARLS & HIGH-YIELD POINTS¶
• Morphology as Diagnostic Tool: The use of specific descriptive terms (Table 59-3) is essential for formulating a differential diagnosis. • Melanoma Warning: A suspicious lesion must be evaluated for asymmetry, border irregularity, color variegation (black, blue, brown, pink, white), diameter >6 mm, and history of change (itching/pain). • Systemic Implications: Certain skin findings are markers of systemic disease. ◦ Dermatitis herpetiformis → associated with celiac disease. ◦ Angular purpuric patches → indicator of fulminant meningococcemia. ◦ Purpura/Vasculitis → indicates small-vessel inflammation.
Reference Tables¶
TABLE 59-1 Description of Primary Skin Lesions Macule: A flat, colored lesion, <2 cm in diameter, not raised above the…¶
Harrison's 22e, p.377
| Macule: A flat, colored lesion, <2 cm in diameter, not raised above the surface of the surrounding skin. A “freckle,” or ephelid, is a prototypical pigmented macule. |
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| 59 | Approach to the Patient with a Skin Disorder Kim B. Yancey, Thomas J. Lawley |
TABLE 59-2 Description of Secondary Skin Lesions Lichenification: A distinctive thickening of the skin that is…¶
Harrison's 22e, p.377
- Lichenification: A distinctive thickening of the skin that is characterized by
accentuated skinfold markings.
TABLE 59-3 Common Dermatologic Terms Alopecia: Hair loss, partial or complete. Annular: Ring-shaped. Cyst: A soft…¶
Harrison's 22e, p.378
- Alopecia: Hair loss, partial or complete.
TABLE 59-4 Selected Common Dermatologic Conditions DIAGNOSIS Acne vulgaris¶
Harrison's 22e, p.378
| DIAGNOSIS | COMMON DISTRIBUTION | USUAL MORPHOLOGY | DIAGNOSIS C | OMMON DISTRIBUTION | USUAL MORPHOLOGY |
|---|---|---|---|---|---|
| Acne vulgaris | Face, upper back, chest | Open and closed comedones, erythematous papules, pustules, cysts |
Seborrheic Tr keratosis |
unk, face, extremities | Brown plaques with adherent, greasy scale; “stuck on” appearance |
| Blush area of cheeks, nose, forehead, chin |
Erythema, telangiectasias, papules, pustules |
Folliculitis A Impetigo A |
ny hair-bearing area nywhere |
||
| Seborrheic dermatitis |
Scalp, eyebrows, perinasal areas |
Erythema with greasy yellow-brown scale |
Herpes simplex Li | ps, genitalia | Grouped vesicles progressing to crusted erosions |
| Antecubital and popliteal fossae; may be widespread |
Patches and plaques of erythema, scaling, and lichenification; pruritus |
Herpes zoster D b |
ermatomal, usually trunk ut may be anywhere |
||
| Stasis dermatitis | Ankles, lower legs over medial malleoli |
Patches of erythema and scaling on background of hyperpigmentation associated with signs of venous insufficiency |
Varicella F s |
ace, trunk, relative paring of extremities |
Lesions arise in crops and quickly progress from erythematous macules, to papules, to vesicles, to pustules, to crusted sites |
| Palms, soles, sides of fingers, and toes |
Deep vesicles | Pityriasis rosea Tr p fo s |
unk (Christmas tree attern); herald patch llowed by multiple maller lesions |
||
| Allergic contact dermatitis |
Anywhere | Localized erythema, vesicles, scale, and pruritus (e.g., fingers, earlobes—nickel; dorsal aspect of foot—shoe; exposed surfaces—poison ivy) |
Tinea versicolor C pr |
hest, back, abdomen, oximal extremities |
Scaly hyper- or hypopigmented macules |
| Elbows, knees, scalp, lower back, fingernails (may be generalized) |
Papules and plaques covered with silvery scale; nails have pits |
Candidiasis G v |
roin, beneath breasts, agina, oral cavity |
||
| Lichen planus | Wrists, ankles, mouth (may be widespread) |
Violaceous flat-topped papules and plaques |
Dermatophytosis F s |
eet, groin, beard, or calp |
Varies with site (e.g., tinea corporis—scaly annular plaque) |
| Extensor surfaces of arms and thighs, buttocks |
Keratotic follicular papules with surrounding erythema |
Scabies G fi br |
roin, axillae, between ngers and toes, beneath easts |
||
| Melasma | Forehead, cheeks, temples, upper lip |
Tan to brown patches | Insect bites A | nywhere | Erythematous papules with central puncta |
| Periorificial, trunk, extensor surfaces of extremities, flexor wrists, axillae |
Chalk-white macules | Cherry angioma Tr Keloid A Dermatofibroma pr A |
unk nywhere (site of evious injury) nywhere |