Clinical Examination and Approach to Patient

Introduction

Dermatology is a visual discipline, but it is not merely "spot diagnosis." It is a logic-driven process of pattern analysis. The goal of the clinical examination is to convert the chaotic visual data of a rash into a structured semiological description language that narrows the differential diagnosis.

This chapter outlines the Diagnostic Algorithm: The standardized method to approach any skin patient.

1.1 "Distance-First" Rule

Do not rush to the single lesion. Diagnosis begins from the door.

General Impression: Is the patient sick? (Sepsis, erythroderma).
Scope: Is it localized or generalized?
Pattern: Is there symmetry? Is there a geometric shape?

[!TIP] The 10-Second Pause: Force yourself to look at the patient from 1 meter away for 10 seconds before touching the skin. This reveals the Distribution, which is often lost when you focus on the primary lesion.

1.2 Seven Dimensions of a Rash

Every dermatosis must be defined by seven parameters. Use this checklist for every patient.

Primary Lesion: What is the fundamental unit? (e.g., Papule).
Secondary Changes: Has it evolved? (e.g., Crusting, excoriation).
Surface: Is it scaly, smooth, verrucous, eroded?
Color: Red (vascular), Brown (pigment), White (sclerosis/depigmentation), Yellow (lipid/pus).
Arrangement: Within the lesion or group. (e.g., Annular, Grouped/Herpetiform).
Distribution: Where is it on the body? (e.g., Acral, Flexural).
Palpability: Soft, firm, hard, indurated.

1.3 History Taking: "Detective" Questions

In dermatology, the history is tailored to discriminate between morphological look-alikes.

Domain	Key Question	Diagnostic Implication
Chronology	"Did it appear suddenly or gradually?"	Acute (Infection/Drug) vs Chronic (Inflammatory).
Symptoms	"Does it itch, hurt, or burn?"	Itch: Eczema, Scabies, Lichen Planus.<br>Pain: Herpes Zoster, Vasculitis (small vessel), Glomus tumor.<br>Burn: Neurogenic, Rosacea.
Trigger	"New medications? Sun exposure?"	Drug eruption, Photosensitivity (Lupus).
Context	"Joint pain? Fever?"	Psoriatic arthritis, Connective tissue disease.
Contacts	"Does anyone else at home itch?"	Scabies.

1.4 Physical Examination

Tools of the Trade

Good Light: Natural sunlight is gold standard. Side-lighting (tangential) reveals elevation.
Magnification: Hand lens (x7) or Dermatoscope.
Touch: Essential.
- Roughness: Scale (Actinic Keratosis).
- Induration: Dermal thickening (Scleroderma, Morphea).
- Infiltration: "Apple jelly" feel (Sarcoid, Lupus Vulgaris).
- Temperature: Hot (Cellulitis/Erysipela) vs Cold (Ischemia).

"Full Skin check"

Scalp: Often missed. Look for seborrheic dermatitis, nevi, or alopecia.
Nails: Pitting (Psoriasis), Splinter hemorrhages (Endocarditis/Trauma).
Mucosa: Oral/Genital. Critical for Lichen Planus, Pemphigus, Behçet's.
Intertriginous Areas: Toe webs (Tinea pedis), groin (Candida/Erythrasma).

1.5 Diagnostic Reasoning Styles

1. "Gestalt" (Type 1 Thinking)

Method: Instant recognition based on experience. "It looks like Psoriasis."
Risk: Confirmation bias. Can miss atypical presentations.

2. Analytical Approach (Type 2 Thinking)

Method: Step-by-step deconstruction.
- "Primary lesion is a papule."
- "It is flat-topped and polygonal."
- "It is purple."
- "Therefore, it is Lichen Planus."
Use: Essential for complex cases or when Gestalt fails. This volume teaches this method.

1.6 Algorithm: From Morphology to Diagnosis

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1.7 Pitfalls to Avoid

Tunnel Vision: Focusing on the first lesion seen.
"Incognito" Diagnosis: Treating with steroids before diagnosis. Changes the morphology (Tinea incognito, Scabies incognito).
Ignoring the Nails: They often hold the clue to the skin rash (e.g., Psoriasis, Lichen Planus).
Describing, not Naming: Don't jump to "It's eczema." Describe "Erythematous, ill-defined, pruritic patch with excoriation." This keeps your mind open to T-cell lymphoma, Contact dermatitis, etc.