Pediatric Dermatology Clinic: History, Physical Exam, and Differential Diagnoses
ATOPIC DERMATITIS / ECZEMA
Key History Questions
- Pruritus is mandatory: Ask specifically about scratching or rubbing behavior in the child 1
- Age of onset: Did symptoms begin in the first two years of life? 1
- Distribution pattern: Has there been itchiness in skin creases (elbows, neck) or on cheeks in children under 4 years? 1
- Atopic history: Does the child or first-degree relatives have asthma, hay fever, or other atopic diseases? 1
- Dry skin: Has there been general dry skin in the past year? 1
- Aggravating factors: Exposure to soaps, detergents, irritants, extremes of temperature 1
- Sleep disturbance: How much is the child's sleep affected? 1
- Immunization history: Have vaccinations (MMR, pertussis) been omitted? 1
- Dietary manipulation: Are parents restricting diet without medical guidance? 1
- Previous treatments: What has been tried and what was the response? 1
- Impact on quality of life: Effect on school work, social life, family stress 1
Physical Examination Findings
- Age-specific distribution patterns are critical: In infants, look for involvement of cheeks, neck, trunk, and extensor surfaces with sparing of the diaper area 2
- After age 2-4 years: Transition to flexural pattern (antecubital and popliteal fossae) 2
- Acute lesions: Erythema, exudation, papules, vesiculopapules 2
- Chronic lesions: Lichenification, scaling, xerosis 1
- Signs of infection: Crusting or weeping suggests bacterial superinfection with Staphylococcus aureus 1, 2
- Eczema herpeticum: Multiple uniform "punched-out" erosions or grouped vesicles indicate herpes simplex infection—this is a medical emergency 1, 3
- Document extent and severity: Record body surface area involved 1
Differential Diagnoses
- Seborrheic dermatitis: Greasy yellow scales on scalp, face, and flexures; less pruritic 4
- Contact dermatitis: Sharp demarcation at site of allergen exposure 5
- Scabies: Look for burrows in finger webs, axillae, genitalia 2
- Tinea corporis: Annular lesions with central clearing and active scaly border 6
- Psoriasis: Well-demarcated plaques with silvery scale, nail pitting 7, 6
- Immunodeficiency disorders: Check for recurrent systemic infections, petechiae, failure to thrive 2, 6
- Nutritional deficiencies: Zinc, essential fatty acids, biotin deficiency 6, 5
- Drug eruptions: Temporal relationship to medication initiation 5
TINEA (DERMATOPHYTE INFECTIONS)
Key History Questions
- Exposure history: Contact with infected individuals, animals (especially cats, dogs), or contaminated surfaces 4
- Location and spread: Where did it start and how has it progressed? 4
- Pruritus: Is it itchy? (Usually yes for tinea) 4
- Previous antifungal treatment: What has been tried and response? 4
- Immunocompromised state: Any underlying conditions affecting immunity? 6
Physical Examination Findings
- Tinea corporis: Annular or arcuate plaques with raised, scaly, erythematous border and central clearing 4
- Tinea capitis: Scaling, alopecia, broken hairs ("black dots"), kerion (boggy, purulent mass) 4
- KOH preparation: Scrape active border for microscopy to confirm hyphae 4
- Wood's lamp: Some species fluoresce (though most common ones do not) 4
Differential Diagnoses
- Nummular eczema: Coin-shaped plaques but lack active border and central clearing 4
- Pityriasis rosea: Herald patch followed by "Christmas tree" distribution 4
- Granuloma annulare: Non-scaly annular lesions 4
- Psoriasis: Thicker scale, less central clearing 4
- Seborrheic dermatitis (for tinea capitis): Greasy yellow scales without alopecia 4
RECURRENT APHTHOUS ULCERS
Key History Questions
- Frequency and duration: How often do ulcers occur and how long do they last? (typically 7-14 days)
- Size and number: Small (minor), large (major), or multiple tiny (herpetiform)?
- Pain level: Aphthous ulcers are typically very painful
- Triggers: Stress, trauma, certain foods (citrus, tomatoes, nuts), menstrual cycle
- Systemic symptoms: Fever, malaise, genital ulcers, eye inflammation, GI symptoms
- Family history: Often positive for recurrent aphthous ulcers
- Nutritional deficiencies: Iron, folate, B12, zinc deficiency
Physical Examination Findings
- Location: Typically on non-keratinized mucosa (buccal, labial mucosa, tongue, soft palate)
- Appearance: Round or oval ulcers with gray-white pseudomembrane and erythematous halo
- Size classification: Minor (<1 cm), major (>1 cm), herpetiform (multiple 1-2 mm)
- Examine for systemic disease: Skin lesions, genital ulcers, eye findings, joint swelling
Differential Diagnoses
- Herpes simplex: Vesicles that rupture, typically on keratinized mucosa (hard palate, gingiva)
- Behçet's disease: Recurrent oral and genital ulcers, uveitis, skin lesions
- Inflammatory bowel disease: Associated GI symptoms, perianal disease
- Cyclic neutropenia: Periodic fever, infections
- Hand-foot-mouth disease: Vesicles on hands, feet, and oral cavity
- Erythema multiforme: Target lesions on skin, lip involvement
ACNE VULGARIS
Key History Questions
- Age of onset: Typically begins in early adolescence
- Distribution: Face, chest, back involvement
- Menstrual history (in females): Relationship to menstrual cycle, irregular periods
- Cosmetic and hair product use: Comedogenic products
- Medications: Corticosteroids, lithium, anticonvulsants, androgens
- Family history: Often positive for acne
- Previous treatments: What has been tried and response
- Signs of hyperandrogenism: Hirsutism, irregular menses, rapid progression
Physical Examination Findings
- Comedones: Open (blackheads) and closed (whiteheads)
- Inflammatory lesions: Papules, pustules, nodules, cysts
- Distribution: Face (especially T-zone), chest, upper back
- Scarring: Atrophic, hypertrophic, or keloid scars
- Signs of hyperandrogenism: Hirsutism, acanthosis nigricans, androgenic alopecia
Differential Diagnoses
- Rosacea: Flushing, telangiectasias, no comedones, older age
- Folliculitis: Monomorphic pustules, often on trunk
- Perioral dermatitis: Papules and pustules around mouth, sparing vermillion border
- Drug-induced acne: Sudden onset, monomorphic lesions
- Acne mechanica: Friction-related, under helmets or sports equipment
DERMATITIS HERPETIFORMIS
Key History Questions
- Intense pruritus: Burning, stinging sensation before lesions appear
- Gastrointestinal symptoms: Diarrhea, bloating, abdominal pain (celiac disease)
- Family history: Celiac disease or dermatitis herpetiformis
- Dietary history: Response to gluten-containing foods
- Age of onset: Can occur in children but more common in adults
Physical Examination Findings
- Distribution: Symmetrical on extensor surfaces (elbows, knees, buttocks, scalp, shoulders)
- Lesions: Grouped vesicles on erythematous base ("herpetiform" pattern)
- Excoriations: Often prominent due to intense pruritus
- Hyperpigmentation: Post-inflammatory changes at sites of healed lesions
Differential Diagnoses
- Linear IgA bullous dermatosis: Similar distribution but different immunofluorescence pattern
- Bullous pemphigoid: Larger, tense bullae, different age distribution
- Scabies: Burrows, different distribution (web spaces, genitalia)
- Atopic dermatitis: Different distribution, no true vesicles 1
HEMANGIOMA (INFANTILE HEMANGIOMA)
Key History Questions
- Age of onset: Typically appears in first weeks of life (not present at birth)
- Growth pattern: Rapid proliferation in first 6-12 months, then involution
- Prenatal history: Prematurity, low birth weight, multiple gestation
- Location: Face, neck, trunk—note if near eyes, nose, mouth, or airway
- Associated symptoms: Breathing difficulty, feeding problems, visual obstruction
- Number of lesions: Single vs. multiple (>5 suggests visceral involvement)
Physical Examination Findings
- Appearance: Bright red, raised, compressible nodule or plaque ("strawberry" appearance)
- Deep component: Bluish hue if deeper dermal or subcutaneous involvement
- Size and location: Measure dimensions, note proximity to vital structures
- PHACES syndrome screening: Large facial hemangioma—check for posterior fossa malformations, arterial anomalies, cardiac defects, eye abnormalities, sternal clefting
- Visceral involvement: If >5 cutaneous hemangiomas, evaluate for hepatic hemangiomas
Differential Diagnoses
- Port-wine stain (capillary malformation): Present at birth, flat, does not proliferate or involute
- Pyogenic granuloma: Rapidly growing, often post-trauma, bleeds easily
- Kaposiform hemangioendothelioma: Violaceous, infiltrative, associated with thrombocytopenia
- Tufted angioma: Slowly growing, can have pain or hyperhidrosis
SEBORRHEIC DERMATITIS
Key History Questions
- Age of onset: Common in infants (first 3 months) and adolescents/adults 4
- Distribution: Scalp ("cradle cap"), face (especially nasolabial folds, eyebrows), chest, flexures 4
- Pruritus: Usually minimal or absent (unlike atopic dermatitis) 4
- Immunocompromised state: HIV/AIDS patients have severe, resistant cases 4
- Neurologic disorders: Parkinson's disease association in adults 4
Physical Examination Findings
- Scalp: Greasy, yellow, adherent scales ("cradle cap" in infants) 4
- Face: Erythema and greasy scales in nasolabial folds, eyebrows, glabella 4
- Flexures: Intertriginous areas with erythema and scale 4
- Chest: V-shaped distribution on anterior chest 4
- Minimal pruritus: Helps distinguish from atopic dermatitis 4
Differential Diagnoses
- Atopic dermatitis: More pruritic, different distribution in infants (spares diaper area), family history 1, 4
- Psoriasis (sebopsoriasis): Thicker, silvery scales, well-demarcated plaques 4
- Tinea capitis: Alopecia, broken hairs, positive KOH 4
- Candidiasis: Satellite pustules, more common in diaper area 4
- Langerhans cell histiocytosis: Purpuric or hemorrhagic component, systemic symptoms 6
PITYRIASIS ALBA
Key History Questions
- Age: Most common in children aged 3-16 years
- Pruritus: Usually minimal or absent
- Sun exposure: Lesions become more apparent after sun exposure (surrounding skin tans)
- Atopic history: Often associated with atopic dermatitis or dry skin
- Seasonal variation: May be more noticeable in summer
Physical Examination Findings
- Location: Face (especially cheeks), upper arms, neck, trunk
- Appearance: Hypopigmented, round or oval patches with fine scale
- Borders: Ill-defined, blending into surrounding skin
- Size: Typically 0.5-5 cm in diameter
- No inflammation: Minimal erythema, unlike active eczema
Differential Diagnoses
- Tinea versicolor: KOH positive, more truncal distribution, fine scale
- Vitiligo: Complete depigmentation (chalk-white), well-demarcated borders
- Post-inflammatory hypopigmentation: History of preceding inflammation
- Nevus depigmentosus: Present from birth, stable, does not change with sun exposure
HYPOPIGMENTATION ON CHIN AND NECK (WORSE IN SUN)
Key History Questions
- Onset and progression: When first noticed, has it changed over time?
- Sun exposure: Does it become more noticeable after sun exposure?
- Preceding inflammation: Any rash, injury, or infection before hypopigmentation?
- Atopic history: Eczema, dry skin, allergies
- Chemical exposure: Cosmetics, perfumes, jewelry (contact dermatitis)
- Family history: Vitiligo, autoimmune diseases
Physical Examination Findings
- Distribution: Chin, neck—note if symmetrical or asymmetrical
- Degree of pigment loss: Partial (hypopigmentation) vs. complete (depigmentation)
- Border characteristics: Well-demarcated (vitiligo) vs. ill-defined (pityriasis alba)
- Scale: Presence suggests pityriasis alba or post-inflammatory change
- Wood's lamp examination: Enhances contrast in vitiligo
Differential Diagnoses
- Pityriasis alba: Ill-defined hypopigmented patches with fine scale, common on face
- Vitiligo: Complete depigmentation, well-demarcated, may have perioral/periocular involvement
- Post-inflammatory hypopigmentation: History of preceding dermatitis or trauma
- Tinea versicolor: Fine scale, KOH positive, usually truncal
- Chemical leukoderma: Contact with depigmenting agents (phenolic compounds)
SCARRING ALOPECIA
Key History Questions
- Onset and progression: Gradual vs. sudden, stable vs. progressive
- Symptoms: Pain, burning, pruritus, tenderness
- Hair care practices: Tight hairstyles (traction alopecia), chemical treatments, heat styling
- Preceding scalp conditions: Folliculitis, kerion, trauma, burns
- Systemic symptoms: Fever, weight loss, fatigue (suggesting systemic disease)
- Medications: Chemotherapy, immunosuppressants
- Family history: Autoimmune diseases, similar hair loss
Physical Examination Findings
- Loss of follicular ostia: Smooth, shiny scalp surface (hallmark of scarring alopecia)
- Distribution pattern: Patchy, linear (morphea en coup de sabre), or diffuse
- Inflammation: Erythema, scale, pustules, crusting
- Peripheral activity: Active inflammation at margins with central scarring
- Associated findings: Skin changes elsewhere (discoid lupus, lichen planopilaris)
Differential Diagnoses
- Discoid lupus erythematosus: Erythematous plaques with follicular plugging, atrophy, dyspigmentation
- Lichen planopilaris: Perifollicular erythema and scale, progressive
- Folliculitis decalvans: Pustules, crusting, tufted hairs
- Dissecting cellulitis: Boggy nodules, sinus tracts, purulent drainage
- Traction alopecia: History of tight hairstyles, marginal involvement
- Kerion: Boggy, purulent mass from severe tinea capitis 4
- Morphea en coup de sabre: Linear induration with alopecia (see below)
NUMMULAR ECZEMA
Key History Questions
- Age: Can occur in children but more common in adults
- Pruritus: Usually intensely pruritic
- Xerosis: Associated with dry skin, worse in winter
- Triggers: Stress, dry environment, irritants
- Previous treatments: Response to topical steroids and emollients
- Atopic history: May or may not have personal/family history of atopy
Physical Examination Findings
- Morphology: Coin-shaped (nummular), well-demarcated plaques
- Location: Extensor surfaces of extremities, trunk
- Appearance: Erythematous, edematous, with vesicles or crusting in acute phase
- Chronic lesions: Lichenified, scaly plaques
- Distribution: Multiple discrete lesions, often symmetrical
Differential Diagnoses
- Tinea corporis: Active scaly border with central clearing, KOH positive 4
- Psoriasis: Thicker silvery scale, different distribution
- Contact dermatitis: History of exposure, different morphology
- Atopic dermatitis: Different distribution (flexural), more diffuse 1
MOLLUSCUM CONTAGIOSUM
Key History Questions
- Exposure: Contact with infected individuals, swimming pools, shared towels
- Duration: How long have lesions been present?
- Spread: Are new lesions appearing?
- Atopic dermatitis: More extensive disease in atopic children 1
- Immunocompromised state: HIV, immunosuppressive medications (extensive, atypical lesions)
- Autoinoculation: Scratching, shaving
Physical Examination Findings
- Morphology: Dome-shaped, flesh-colored to pink papules with central umbilication
- Size: Typically 2-5 mm, can be larger in immunocompromised
- Distribution: Face, trunk, extremities, genital area (non-sexual in children)
- Number: Few to hundreds
- Surrounding dermatitis: "Molluscum dermatitis" (eczematous reaction around lesions)
Differential Diagnoses
- Verruca vulgaris (warts): Rough surface, no central umbilication
- Folliculitis: Pustular, no umbilication
- Milia: Smaller, white, no umbilication
- Basal cell carcinoma: Rare in children, pearly with telangiectasias
LICHEN PLANUS
Key History Questions
- Pruritus: Usually intensely pruritic
- Oral involvement: Painful oral lesions, white lacy pattern
- Nail changes: Ridging, thinning, pterygium
- Medications: Drug-induced lichenoid eruptions (thiazides, beta-blockers, antimalarials)
- Hepatitis C: Association in adults (less relevant in children)
- Duration: Chronic course, may last months to years
Physical Examination Findings
- Classic "6 Ps": Purple, polygonal, planar, pruritic papules and plaques
- Wickham's striae: Fine white lines on surface of lesions
- Distribution: Flexor wrists, ankles, lower back, genitalia
- Koebner phenomenon: Lesions at sites of trauma
- Oral mucosa: White lacy pattern (Wickham's striae), erosions
- Nails: Longitudinal ridging, thinning, pterygium, nail loss
Differential Diagnoses
- Psoriasis: Thicker silvery scale, extensor surfaces
- Eczema: Less well-defined, different morphology 1
- Lichenoid drug eruption: Medication history, similar appearance
- Secondary syphilis: Palmoplantar involvement, lymphadenopathy, serology positive
LICHEN PLANUS PIGMENTOSUS
Key History Questions
- Onset: Gradual appearance of dark patches
- Sun exposure: Often on sun-exposed areas
- Pruritus: May or may not be present
- Preceding inflammation: History of lichen planus or other inflammatory condition
- Ethnicity: More common in darker skin types (Fitzpatrick IV-VI)
- Medications: Drug-induced pigmentation
Physical Examination Findings
- Morphology: Diffuse or patchy brown to gray-brown macules
- Distribution: Face (especially forehead, temples), neck, upper trunk, flexures
- No active inflammation: Typically no scale or erythema
- Ill-defined borders: Blends into surrounding skin
- Symmetrical: Often bilateral and symmetrical
Differential Diagnoses
- Erythema dyschromicum perstans (ashy dermatosis): Gray-blue macules, may have erythematous border initially
- Post-inflammatory hyperpigmentation: History of preceding inflammation
- Melasma: Facial distribution, associated with sun exposure, hormones
- Drug-induced hyperpigmentation: Medication history (minocycline, antimalarials)
ERYTHEMA DYSCHROMICUM PERSTANS (ASHY DERMATOSIS)
Key History Questions
- Onset: Gradual appearance of gray-blue patches
- Preceding erythema: Some patients report initial red border
- Pruritus: Usually absent
- Ethnicity: More common in Latin American populations
- Medications: Rule out drug-induced pigmentation
- Systemic symptoms: Usually none
Physical Examination Findings
- Morphology: Asymptomatic gray-blue to slate-gray macules and patches
- Active border: May have erythematous border in early lesions
- Distribution: Trunk, neck, upper extremities, face
- Size: Variable, can coalesce into large patches
- No scale or atrophy: Smooth surface
Differential Diagnoses
- Lichen planus pigmentosus: Brown rather than gray, may have history of lichen planus
- Post-inflammatory hyperpigmentation: History of preceding dermatitis
- Drug-induced pigmentation: Medication history
- Idiopathic eruptive macular pigmentation: Smaller, more numerous macules
IDIOPATHIC ERUPTIVE MACULAR PIGMENTATION
Key History Questions
- Age of onset: Typically children and young adults
- Sudden appearance: Multiple pigmented macules appearing over weeks to months
- Asymptomatic: No pruritus or other symptoms
- Spontaneous resolution: Lesions may fade over months to years
- No preceding inflammation: No history of rash or trauma
Physical Examination Findings
- Morphology: Multiple small (2-5 mm) brown to red-brown macules
- Distribution: Trunk, neck, proximal extremities
- No scale or inflammation: Smooth, flat macules
- Number: Numerous, can be hundreds
- Symmetrical: Often bilateral distribution
Differential Diagnoses
- Erythema dyschromicum perstans: Larger, gray-blue patches
- Lichen planus pigmentosus: Larger patches, different color
- Mastocytosis (urticaria pigmentosa): Darier's sign positive (urtication with rubbing)
- Post-inflammatory hyperpigmentation: History of preceding inflammation
MORPHEA (LOCALIZED SCLERODERMA)
Key History Questions
- Onset and progression: When first noticed, is it expanding?
- Symptoms: Pruritus, pain, tightness (usually minimal)
- Trauma: Preceding injury to area (Koebner phenomenon)
- Systemic symptoms: Joint pain, muscle weakness, neurologic symptoms
- Family history: Autoimmune diseases
- Medications: Rule out drug-induced scleroderma
Physical Examination Findings
- Morphology: Well-demarcated, indurated plaques with ivory-colored center
- Active border: Violaceous or erythematous rim (lilac ring) in active lesions
- Atrophy: Central atrophy, loss of hair follicles and sweat glands
- Distribution: Trunk, extremities (plaque morphea), linear (limbs), or en coup de sabre (scalp/face)
- Depth: Assess for involvement of underlying muscle, bone (especially in linear forms)
- Extracutaneous involvement: Joint contractures, limb length discrepancy, neurologic deficits
Differential Diagnoses
- Lichen sclerosus: White, atrophic patches, often genital
- Vitiligo: Depigmentation without induration or atrophy
- Post-inflammatory hypopigmentation: No induration
- Atrophoderma of Pasini and Pierini: Depressed patches without induration
MORPHEA EN COUP DE SABRE
Key History Questions
- Age of onset: Usually childhood or adolescence
- Progression: Is the lesion expanding or stable?
- Neurologic symptoms: Seizures, headaches, visual changes
- Ophthalmologic symptoms: Vision changes, eye pain
- Dental problems: Tooth loss, jaw asymmetry
- Facial asymmetry: Progressive hemifacial atrophy
Physical Examination Findings
- Location: Linear, frontoparietal distribution ("sword strike" pattern)
- Morphology: Linear band of induration and atrophy extending from scalp to face
- Scarring alopecia: Hair loss along the band
- Skin changes: Hyperpigmentation or hypopigmentation, atrophy
- Facial asymmetry: Hemifacial atrophy, enophthalmos
- Neurologic examination: Focal deficits, seizure activity
- Ophthalmologic examination: Uveitis, episcleritis, retinal changes
Differential Diagnoses
- Parry-Romberg syndrome (progressive hemifacial atrophy): Deeper tissue involvement without skin changes
- Linear morphea: Similar but different distribution (limbs, trunk)
- Nevus of Ota: Pigmentation without induration or atrophy
- Trauma or burn scar: History of injury
COMMON PITFALLS TO AVOID
For Atopic Dermatitis:
- Do not delay treatment of eczema herpeticum—multiple uniform "punched-out" erosions require immediate systemic acyclovir 3
- Do not use sedating antihistamines for pruritus control, especially in elderly (though less relevant in pediatrics) 8
- Do not overlook bacterial superinfection—crusting and weeping require antibiotics (flucloxacillin for S. aureus) 1, 3
For All Conditions:
- Always consider immunodeficiency if skin infections are recurrent or severe 2, 6
- Perform KOH preparation before diagnosing eczema if annular lesions are present (rule out tinea) 4
- Biopsy atypical or treatment-resistant lesions to confirm diagnosis 5
- Screen for systemic involvement in morphea en coup de sabre (neuroimaging, ophthalmology referral)
- Recognize that multiple conditions can coexist—atopic dermatitis patients are prone to secondary infections and contact dermatitis 1, 6