19.2 Dermatology

Dermatology accounts for roughly 11% of Associated Clinical Sciences on NBCE Part II. Chiropractors routinely inspect skin on the back, shoulders, and scalp that patients never see themselves, so the boards test two skills: naming what you see with correct morphology vocabulary, and recognizing which lesions are benign, infectious, or malignant enough to demand urgent referral.

Lesion Morphology: The Foundation

Precise terminology is the language of dermatology. The 1 cm threshold and whether a lesion is flat, solid, or fluid-filled do most of the classifying.

Primary Lesions

Secondary Lesions

Scale (flaking), crust (dried serum/blood/pus), erosion (shallow loss of epidermis), ulcer (deeper tissue loss), lichenification (thickened skin from chronic rubbing), fissure (linear crack), and scar (fibrotic replacement) describe how primary lesions evolve.

Infections

Bacterial

• Impetigo — honey-colored crusts, highly contagious; Staphylococcus aureus or Streptococcus pyogenes
• Cellulitis — spreading erythema, warmth, tenderness; requires antibiotics; distinguish from deep vein thrombosis and contact dermatitis
• Folliculitis — pustules centered on hair follicles
• Erysipelas — well-demarcated raised border, often on face; group A strep

Viral

• Herpes simplex — grouped vesicles on erythematous base; HSV-1 (oral) and HSV-2 (genital)
• Herpes zoster (shingles) — painful vesicular eruption in a dermatomal distribution; do not adjust through active vesicles; postherpetic neuralgia is a complication
• Verruca vulgaris (warts) — hyperkeratotic papules; HPV
• Molluscum contagiosum — umbilicated pearly papules

Fungal

• Tinea corporis (ringworm) — annular plaque with central clearing and active scaly border; KOH prep shows hyphae
• Tinea pedis — interdigital maceration, scaling; athlete's foot
• Tinea capitis — scaly patches with broken hairs; requires systemic antifungals
• Candidiasis — beefy red plaques with satellite pustules in intertriginous areas

Tumors: Benign and Malignant

Benign

• Seborrheic keratosis — waxy, stuck-on appearance; "barnacle" of aging
• Cherry angioma — bright red papule; common with age
• Lipoma — soft, mobile subcutaneous nodule
• Dermatofibroma — firm dimple sign on lateral compression

Premalignant and Malignant

• Actinic keratosis — rough, scaly patch on sun-exposed skin; precursor to SCC
• Basal cell carcinoma (BCC) — most common skin cancer; pearly papule with rolled border and telangiectasia; rarely metastasizes
• Squamous cell carcinoma (SCC) — keratotic nodule or ulcer on sun-damaged skin; can metastasize
• Melanoma — most dangerous; use ABCDE: Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolution. The ugly duckling sign — one nevus unlike the others — is a referral trigger

Any suspicious pigmented lesion, nonhealing ulcer, or rapidly growing nodule warrants dermatology referral — not observation in a chiropractic office.

Dermatitis

Scaling Diseases

• Psoriasis — well-demarcated erythematous plaques with silvery micaceous scale on extensor surfaces, scalp, and sacrum. Auspitz sign (pinpoint bleeding when scale removed) and Koebner phenomenon (lesions at sites of trauma) are classic. Associated with psoriatic arthritis
• Pityriasis rosea — herald patch followed by Christmas-tree distribution on trunk; self-limited
• Lichen planus — pruritic polygonal purple papules (the 6 P's); Wickham striae on oral mucosa

Vesicular and Bullous Disorders

• Dyshidrotic eczema — pruritic vesicles on palms and soles
• Dermatitis herpetiformis — intensely pruritic vesicles on extensor surfaces; associated with celiac disease
• Bullous pemphigoid — tense bullae in elderly; autoimmune, subepidermal split; Nikolsky sign negative
• Pemphigus vulgaris — flaccid bullae with painful mucosal erosions; intraepidermal split; Nikolsky sign positive

Pigmentary Disorders

• Vitiligo — depigmented patches; autoimmune destruction of melanocytes
• Melasma — symmetric hyperpigmented patches on face; associated with hormones and sun
• Post-inflammatory hyperpigmentation — darkening after inflammation or injury
• Albinism — congenital absence of melanin; increased skin cancer and vision risk

Hair and Sebaceous Disorders

• Acne vulgaris — comedones, papules, pustules, nodules; driven by androgens, sebum, Cutibacterium acnes, and follicular plugging
• Rosacea — centrofacial erythema, telangiectasia, papulopustules; triggers include heat, alcohol, and spicy food
• Alopecia areata — smooth round patches of hair loss; autoimmune
• Androgenetic alopecia — patterned thinning; male and female patterns differ
• Telogen effluvium — diffuse shedding after physiologic stress (surgery, illness, childbirth)

Chiropractic Relevance

During examination you may be the first clinician to notice a changing mole on the upper back, shingles in a thoracic dermatome before the vesicles appear, or cellulitis masquerading as local musculoskeletal pain. Document findings, avoid manipulating through infected or vesicular skin, and refer promptly when malignancy or systemic infection is suspected.