Dermatological Examination

Exam Essentials - Gear Up & Gaze

• Lighting: Optimal: natural daylight. Wood's lamp for specific fluorescence (e.g., fungal, pigmentary).
• Essential Gear: Magnifying lens (handheld, 10-20x), dermatoscope, glass slide (for diascopy), flexible ruler, gloves, camera.
• Initial Gaze:
  • Assess patient's general health.
  • Note skin phototype (Fitzpatrick I-VI).
  • Observe lesion distribution (e.g., acral, flexural) & overall pattern.

⭐ Diascopy is crucial: distinguishes vascular erythema (blanches) from purpura/telangiectasia (non-blanching).

History Hints - Patient Puzzles

• Onset & Duration: Acute, chronic, recurrent?
• Pruritus: Timing, severity. Associated pain/burning?
• Lesion Evolution: Initial site, spread, changes (color, texture).
• Triggers: Sun, heat, stress, drugs, allergens.
• Past Hx: Atopy (eczema, asthma), prior skin issues.
• Drug Hx: All current/recent (Rx, OTC, herbal).
• Family Hx: Psoriasis, atopy.
• Occupation/Travel: Exposures, recent trips.
• Systemic: Fever, weight loss, arthralgia.

⭐ Drug history is key; eruptions mimic many dermatoses. Note all new medications.

Primary Lesions - Spot Spectrum

• Flat, non-palpable lesions; color change only.
• Macule:
  • Circumscribed, < 1 cm in diameter.
  • Color change, no elevation/depression.
  • E.g., Freckles, lentigines, junctional nevi, tinea versicolor.
• Patch:
  • A macule > 1 cm in diameter.
  • Flat, non-palpable, color change.
  • E.g., Café-au-lait spot, vitiligo, port-wine stain, mongolian spot.
• 📌 Macule = Mini (<1cm); Patch = Plainly Prominent (>1cm).

⭐ > The key differentiator between a macule and a patch is size (<1cm vs >1cm); both are primary, flat, non-palpable lesions representing a color alteration.

Secondary Signs - Evolution Evidence

• Scales: Shedding epidermal flakes (e.g., psoriasis, tinea).
• Crusts: Dried exudate; honey-colored (impetigo), hemorrhagic, serous.
• Erosions: Superficial epidermal loss; heals without scarring.
• Ulcers: Deeper dermal/subcutaneous loss; heals with scarring.
• Fissures: Linear skin cracks (e.g., hand eczema, angular cheilitis).
• Atrophy: Skin thinning; epidermal, dermal, or subcutaneous.
• Lichenification: Thickened skin, exaggerated markings from chronic rubbing.
• Excoriations: Scratch marks, often linear, self-induced.
• Scars: Post-injury fibrous tissue; hypertrophic, atrophic.

⭐ Lichenification is a hallmark of chronic rubbing or scratching, classically seen in conditions like atopic dermatitis or lichen simplex chronicus, indicating chronicity of the lesion.

Patterns & Probes - Clue Clusters

• Distribution Clues:
  • Symmetrical: Eczema, Psoriasis.
  • Flexural: Atopic dermatitis; Extensor: Psoriasis.
  • Photosensitive: SLE; Dermatomal: Herpes Zoster.
  • Koebner phenomenon: Psoriasis, Lichen Planus, Vitiligo.
• Configuration Clues:
  • Annular: Tinea corporis, Granuloma annulare.
  • Linear: Lichen striatus, Koebner.
  • Grouped (Herpetiform): Herpes simplex/zoster.
  • Targetoid: Erythema multiforme.
• Diagnostic Probes:
  • Diascopy: Differentiates vascular (blanchable) from hemorrhagic.
  • Dermoscopy: Magnified view of structures, patterns.
  • Wood's Lamp: Detects fluorescence (e.g., Microsporum).

⭐ > The Koebner phenomenon (isomorphic response) refers to the appearance of new skin lesions on previously unaffected skin secondary to trauma; classically seen in psoriasis, lichen planus, and vitiligo.

High‑Yield Points - ⚡ Biggest Takeaways

• Inspection is paramount: note lesion morphology (type, shape, arrangement, distribution) and color.
• Palpation evaluates texture, consistency, tenderness, temperature, and mobility of lesions.
• Diascopy distinguishes blanchable erythema (vascular) from non-blanchable purpura (hemorrhagic).
• Wood's lamp examination detects specific fungal/bacterial infections and pigmentary anomalies.
• Dermoscopy visualizes subsurface skin structures, improving diagnosis of pigmented/non-pigmented lesions.
• Skin biopsy (punch, shave, excisional) is vital for histopathological diagnosis in uncertain cases.
• Always conduct a thorough skin examination, including mucous membranes, hair, and nails.