Dermatologic Examination and Diagnosis Comprehensive Notes

Objectives

• Upon module completion, learners will be able to:

  • Conduct a complete dermatologic history (structured and comprehensive).

  • Demonstrate full‐body skin, hair, and nail examination techniques.

  • Contrast normal findings with age-, pregnancy-, and disease-related variations.

  • Detect deviations from expected findings and link them to common pathologies.

  • Formulate initial differential diagnoses (DDx) for skin problems using morphology, location, and history.

  • Recognize dermatologic red flags that signal emergent or systemic disease.

  • Accurately document history, exam, and DDx in SOAP format.

Inclusive Dermatology – Equity Highlight

• 2024 NEJM “Efforts toward Equity” article profiles the Inclusive Dermatology Atlas (UNM).

  • Open, online photo bank spanning Fitzpatrick types I–VI.

  • Purpose: improve diagnostic accuracy & reduce disparities in patients of color.

  • Images are de-identified, consented, created 2022 by UNM + East Carolina U.

  • Counters bias of light-skin-dominant teaching materials.

• Access: Inclusive Dermatology Gallery (web-based, free).

Anatomy & Physiology Review

Skin Structure

• Skin = largest organ; layered:

  • Epidermis → Dermis → Subcutaneous tissue.

Skin Functions

• Barrier to microbes, injury, fluid loss.

• Thermoregulation & BP modulation (vasomotor + sweat).

• Sensory perception & emotional expression (e.g., blushing).

• Vitamin D synthesis (UV-B → cholecalciferol).

• Immune surveillance & wound repair.

• Waste excretion via sweat (urea, lactic acid).

Appendix Structures

• Hair follicles, sebaceous glands, eccrine & apocrine sweat glands, nails.

Epidermis (Thin, avascular)

• Stratum basale (germinativum): mitosis, melanocytes, Merkel cells.

• Stratum spinosum: keratinocytes interconnected by desmosomes.

• Stratum granulosum: lamellar granules (lipid barrier).

• Stratum lucidum: palms & soles only.

• Stratum corneum: dead, keratin-filled cells → waterproof layer.

Dermis

• Papillary layer: dermal papillae ↑ surface area, Meissner corpuscles.

• Reticular layer: collagen + elastin, Pacinian corpuscles, vessels, nerves, hair, glands.

Subcutaneous Tissue

• Adipose + larger vessels.

• Functions: insulation, cushioning, energy storage.

Hair Overview

• Derived from epidermal invagination into dermis; pigment from follicular melanocytes.

• Types:

  • Vellus: fine.

  • Terminal: coarse, pigmented.

• Pilosebaceous unit = follicle + sebaceous gland + arrector pili.

Sweat & Sebaceous Glands

• Eccrine: widely distributed; duct opens on surface; watery sweat; functional ≈1 month age.

• Apocrine: axillae/anogenital; ducts empty into follicles; fatty/protein sweat → odor after bacterial action; activate at adolescence (androgens).

• Sebaceous: holocrine; sebum into follicle; ↑ activity in pregnancy & adolescence (seborrhea); ↓ activity in elders → xerosis.

Nails

• Hard keratin plates over vascular nail bed.

• Landmarks: root, plate, lunula, eponychium (cuticle), hyponychium, folds.

• Aging: slower growth, ridging, thickening.

Lifespan Variations

Infants & Children

• Smooth skin, limited subcutaneous fat, absent apocrine function.

• Birth findings: vernix caseosa, desquamation, lanugo (sheds day 10-14).

• Normal variants: mild acrocyanosis, erythema toxicum, slate-gray (Mongolian) patches, salmon patches, milia.

• Concerning findings: >6 café-au-lait spots (NF1), port-wine stains, patterned bruising/burns, STIs, poor turgor, persistent central cyanosis, jaundice, frenulum lacerations.

• Common disorders: diaper dermatitis, seborrheic dermatitis, atopic dermatitis, viral exanthems, impetigo, warts, HSV-1.

• Red flags: petechiae/purpura in ill child, drug rashes, non-resolving/progressive lesions.

Adolescents

• Androgen surge → apocrine activation, seborrhea, acne.

• Development of terminal hair: axillae, pubic, male face.

• Common issues: warts, STIs.

Pregnancy

• Physiologic: ↑ blood flow, eccrine & sebaceous activity, subdermal fat.

• Hyperpigmentation in $\approx 90\%$: melasma, nipples, linea nigra, axillae, vulva, perianal, umbilicus.

• Striae gravidarum common.

• Vascular changes: telangiectasia, varicosities, palmar erythema, skin tags, mild pruritus.

• Pruritic rash: PUPPP/PEP – starts in striae, spares umbilicus.

• Must-not-miss: Intrahepatic cholestasis of pregnancy → severe palm/sole pruritus, $\uparrow$ bile acids/LFTs, fetal risk (prematurity $\le 60\%$, stillbirth $1!–!2\%$).

• DDx contrasts: atopic eruption, polymorphic eruption, pemphigoid gestationis.

Older Adults

• ↓ sebaceous/sweat activity → xerosis; thinning epidermis, ↓ collagen/elastin, ↓ subcutaneous fat.

• Hair: graying (fewer melanocytes), androgenic alopecia, facial hair in women, thicker ear/nares hair, ↓ axillary/pubic hair.

• Nails: slower growth, ridging, thickening.

• Common benign lesions: cherry angiomas, seborrheic keratoses, solar lentigines.

• ↑ skin-cancer prevalence → thorough inspection.

• Hidden injuries on flexural or covered areas → consider elder abuse.

Dermatologic History Framework

VINDICATE S/P Etiology Mnemonic

• Vascular, Inflammatory/Infection, Neoplastic, Degenerative/Deficiency, Idiopathic/Intoxication, Congenital, Autoimmune/Allergic, Traumatic, Endocrine, Social/Psychological.

Chief Complaints / Common Concerns

• “Rash”, “Hair loss”, “Weird growth”, pruritus, pain, burning, bleeding, color change.

OLDECARTS (HPI)

• Onset, Location, Duration, Evolution, Characteristics, Aggravating/Associated, Relieving, Timing, Severity, Patient perception.

Anatomic Clues (Location × Pattern)

• Scalp: seborrheic dermatitis, tinea capitis.

• Face: melasma, rosacea, acne, impetigo, roseola.

• Torso: pityriasis rosea, tinea versicolor, eczema, seborrheic dermatitis, molluscum contagiosum.

• Arms: keratosis pilaris, psoriasis, eczema, hidradenitis suppurativa.

• Hands/palms & Feet/soles: secondary syphilis, scabies, erythema multiforme, RMSF, Kawasaki, rickettsia.

• Genitals: syphilis, scabies, candidiasis, HSV, balanitis.

• Legs: psoriasis, stasis dermatitis, meningococcemia.

• Pattern terms: fixed, evanescent, migratory.

Past Medical History & Risk Factors

• Prior skin/hair/nail issues, severe sunburns, autoimmune/endocrine/renal/hepatic/vascular/psychiatric disorders, malnutrition, trauma, recent infections, new meds, allergies.

Systemic Disease → Cutaneous Manifestations (selected)

• Diabetes: acanthosis nigricans, infections.

• Thyroid: hyper vs hypo skin traits.

• Cushing: striae, atrophy.

• Cirrhosis: spider angiomas, palmar erythema.

• CKD: uremic frost.

• Celiac: dermatitis herpetiformis, etc.

Family, Social, Skin-Care, ROS Highlights

• Family: atopy, autoimmune, skin cancer, alopecia.

• Social: substances, stress, occupation, sun, travel, pets, sexuality.

• Skin-care habits, recent product changes, CAM use.

• ROS: general + multi-system to catch systemic clues.

Physical Examination of the Integument

Required Equipment

• Ruler, good lighting, Wood’s lamp, magnifier/dermatoscope, gloves, tongue blades, scalpel for scrapings.

Preparation

• Comfortable room temp; drape & fully expose; inspect mucosa, folds, scalp, genitals, nails; infection control.

Techniques

Inspection

• Color/pigment changes (erythema, pallor, cyanosis, jaundice) – in dark skin check palms/soles; central cyanosis → lips/tongue.

• Symmetry, thickness, hygiene, lesions (morphology, distribution, borders).

• Hair: color, distribution, density.

• Nails: color, shape, surface, angle (Shamroth test for clubbing).

• Frequently missed zones: ear, inner canthus, nasal grooves, intergluteal, interdigital, genitals.

Palpation

• Skin: moisture, temp, turgor, texture, mobility, induration, tenderness, blanching, edema, depth, fixation.

• Hair: texture, fragility (tug test), scalp lesions.

• Nails: thickness, adherence, firmness.

• Olfactory clues (e.g., pseudomonas sweet-grape odor).

Special Palpation Signs

• Blanching test (glass slide) differentiates erythema vs purpura.

• Nikolsky sign, dermatographism, Auspitz sign, Koebner phenomenon.

Lesion Description System (memorize!)

• Primary morphology: macule (<1 cm), patch (>1 cm), plaque, papule (<1 cm), nodule (>1 cm), vesicle (<1 cm fluid), pustule (<1 cm pus), bulla (>1 cm fluid), wheal, cyst, burrow, telangiectasia.

• Secondary morphology: scale, crust, erosion, ulcer, fissure, scar, keloid, excoriation, lichenification.

• Configuration: round, annular, linear, zosteriform, target, serpiginous, cluster, confluent, reticular, satellite, lacy, morbilliform.

• Location/distribution: localized, regional, generalized, photodistributed, acral, dermatomal, flexural, extensor, follicular, symmetric, truncal, unilateral.

• Borders: well-demarcated, poorly defined, active/advancing, collarette.

• Color palette: red, violaceous, brown, black, hypopigmented, dusky, pearly, white, purple, yellow, blue (examples provided in transcript).

• Size: measure objectively (cm) or coin reference.

• Texture/other: umbilicated, indurated, waxy, fluctuant, mobile, tender, warm.

Sample Documentation (condensed examples)

• “1 cm pink pearly papule with telangiectasia inferior to L infra-orbital rim – DDx BCC.”

• “Zosteriform vesicles on erythematous base along L T5 dermatome – DDx Herpes zoster.”

• Full list of seven transcript examples included for practice.

Nevi & Skin Cancer

Nevi

• Common: junctional, compound, dermal.

• Atypical nevi: larger, irregular; melanoma precursor risk.

ABCDE Warning Signs of Melanoma

• Asymmetry, Border irregularity, Color variation, Diameter >6\,\text{mm}, Evolution.

Fitzpatrick Phototypes

• I (always burns) → VI (never burns); all need sun protection.

Malignant Melanoma (MM)

• Pigmented papule/plaque, irregular, >6 mm, evolving.

• Types: superficial spreading (commonest), nodular, lentigo maligna, acral lentiginous.

• Risk factors: personal/family MM, atypical nevi, >40 y, male, fair skin, UV/tanning bed, immunosuppression, prior NMSC.

Basal Cell Carcinoma (BCC)

• Most common cancer; sun-exposed sites; pearly telangiectatic papule ± ulcer (“rodent ulcer”).

• Subtypes: nodular (≈80 %), superficial, infiltrative, pigmented.

Cutaneous Squamous Cell Carcinoma (cSCC)

• Malignant keratinocytes invade dermis; papule/plaque/nodule/hyperkeratotic ± ulcer.

• $60\%$ arise from actinic keratoses; lifetime risk $9!–!14\%$; metastasis $2!–!5\%$.

• Light-skinned have ≈$80\times$ higher risk vs dark-skinned.

Actinic Keratosis (AK)

• Rough scaly papule on sun-exposed skin; $\approx10\%$ progress to cSCC.

• Actinic cheilitis = lip variant.

Bowen’s Disease

• cSCC in situ (confined to epidermis).

Prevention Mnemonic

• “Slip (a shirt), Slop (sunscreen), Slap (a hat).”

• Avoid tanning beds.

Nail Findings

• Clubbing: base angle \alpha < 165^{\circ} (normal $\alpha \ge 180^{\circ}$). = pulmonary/cardiac/GI disease.

• Yellow nails: PAD, psoriasis, lymphedema (not always fungus).

• Onychomycosis: thick, yellow, crumbly; confirm with KOH/culture.

• Terry nails, Beau lines, koilonychia → systemic disease clues.

• Ingrown nail ± paronychia; onycholysis (plate separation).

Hair Findings

• Alopecia areata: sudden patches, exclamation-point hairs; autoimmune.

• Traction alopecia: mechanical; frontal/temporal.

• Male pattern: bitemporal recession ± vertex thinning.

• Female pattern: widened part, frontal hairline intact but thinner, occiput spared.

• Telogen vs anagen hairs (trichogram) – diagnostic aid.

• Tinea capitis dermoscopy: comma, corkscrew, broken hairs.

Special Populations & Must-Not-Miss Conditions

• Refer to Lifespan section: neonatal skin signs, intrahepatic cholestasis of pregnancy, elder abuse bruising.

Selected Common Diagnoses & Differentials

• Pediculosis capitis: scalp pruritus; live lice visualization; nits ≠ diagnostic.

  • DDx: seborrheic dermatitis, tinea capitis.

• Tinea corporis: annular plaque with central clearing.

  • DDx: pityriasis rosea, nummular eczema, granuloma annulare, contact dermatitis.

• Herpes zoster: dermatomal vesicles → crust; prodrome; post-herpetic neuralgia risk.

  • DDx list (HSV, cellulitis, etc.) per transcript.

• Acne rosacea: chronic central face erythema, papulopustules, flushing, telangiectasia; ocular involvement.

  • DDx: acne vulgaris, lupus, perioral dermatitis, etc.

• Plaque psoriasis: symmetric silvery plaques on extensors; nail pitting.

  • Variants & extensive DDx list provided above.

Diagnostic Reasoning Pearls

• Combine pattern recognition with OLDECARTS + VINDICATE S/P.

• Always inspect hidden zones, hair, nails, mucosa.

• Use objective tools: ruler, dermatoscope, Wood’s lamp, scrapings, biopsy.

• Document: primary & secondary morphology, configuration, location, borders, color, size, texture.

• DDx template: 4 common, 3 do-not-miss, 2 zebras, 1 quick Google.

• Unsure? biopsy/refer; set timely follow-up.

Ethical / Practical Implications

• Inclusive imagery reduces diagnostic error in skin of color.

• Cutaneous clues enable earlier systemic disease detection.

• Universal sunscreen counseling challenges tanning culture.

• Vigilance for abuse in infants/elders during skin exam.

Numerical / Statistical Highlights

• AK → cSCC progression $\approx10\%$.

• Light-skinned cSCC risk ≈$80\times$ dark-skinned.

• Melanoma “D” criterion: diameter >6\,\text{mm} (≈ pencil eraser).

• Intrahepatic cholestasis: prematurity up to $60\%$; stillbirth $1!–!2\%$.

Formulas / Tests

• Clubbing base angle: \text{Normal:}\; \alpha \ge 180^{\circ}\quad ; \quad \text{Clubbing:}\; \alpha < 165^{\circ}.

• (Body-surface-area burn rules not covered but relevant.)

Conclusion

• Mastery of morphology + methodical history/exam is cornerstone of dermatologic diagnosis.

• Equity, prevention, and systemic context are integral to advanced skin assessment.