Skin Lesions

Resources

• Visual Dx

• BMJ Best Practice for Dermatology

Discoloration

• Definitions: Macules and patches are circumscribed areas of discoloration that

  • Are neither raised nor depressed in relation to surrounding skin, i.e. the lesions cannot be felt when the examiners eyes are closed

  • Differ only in diameter with macules being < 1 cm and patches > 1 cm

• Widespread skin lesions may be composed of both macules and patches

• Remembering the terminology: Macule is derived from the Latin term for "spot." When something is spot-less, it is said to be immaculate. Patches on clothes are large and flat.

Erythematous

• Infectious

  • Viral exanthems: Erythema infectiosum (Parvovirus B19), roseola infantum, pityriasis rosea

  • Bacterial: Cellulitis, erysipelas, cutaneous erythrasma

• Inflammatory

  • Rosacea: Avoid facial flushing triggers, e.g. extreme temperatures, sunlight, spicy foods, alcohol, psychological stress, vasodilatory medications. Apply thin film metronidazole gel 1% daily to affected areas. Alternative agents in order of preference include topical brimonidine (Mirvaso), topical azelaic acid (Finacea), and topical ivermectin (Soolantra).

  • Henoch-Schonlein purpura (HSP - IGA vasculitis)

• Petechiae

  • Platelet dysfunction

  • Vasculitis

  • Rocky Mountain Spotted Fever

Hyperpigmented Lesions

• Melanoma

• Cafe-au-lait spot

• Diffuse hyperpigmentation

  • Hyperthyroidism

  • Addison's disease: Fatigue, anorexia, weight loss, weakness, hyponatremia

  • Hemochromatosis

Superficial

Linear

• Fissure (crack or split)

• Excoriation (erosion)

Deep

• Ulceration (epidermal loss)

  • Pressure ulcer

  • DM foot ulcer

• Tracking: Hidradenitis suppurativa

Epidermal thickening

• Lichenification (exaggeration of skin lines): Atopic dermatitis

• Scale (superficial epidermal thickening)

  • Seborrheic dermatitis: Malassezia infection generally found on scalp, face, trunk, or intertriginous zones. Treat with ketoconazole 2% shampoo (scalp) +/- topical corticosteroids.

  • Tinea (fungal infection)

    • Capitis: Griseofulvin 20 mg/kg/day in two divided doses (MDD 1,000 mg/day) x 6 weeks for children and adults.

    • Corporis, cruris, pedis, and versicolor: Start topical terbinafine 1% BID x 3 weeks. Fluconazole 10 mg/kg/day once daily dosing up to 200 mg qd (adult) x 3 weeks.

• Crust (dried serum or exudate on skin)

  • Impetigo: Red sores typically on the face (nose/mouth) or hands that progress to honey-colored crusts. Associated with Staph aureus and/or Streptococcus pyogenes infection. Treat with topical mupirocin (Bactroban).

  • Healing vesicles: See vesicles below.

• Plaque (elevated, solid flat lesion > 1 cm)

  • Psoriasis: Erythematous oval lesions often on extensor surfaces. Sometimes associated with pitting fingernails and asymmetric polyarthritis. Treat with topical coal tar shampoo, corticosteroids, calcipotriene. If covering > 20% of body surface or refractory, refer to dermatology for ultraviolet phototherapy, LASER excision, methotrexate, or anti-TNF therapy.

  • Lichen planus: Autoimmune response sometimes associated with medications or HCV. Pruritic, polygonal, purple plaques/papules on a white, lace-like pattern (Wickham's striae). Generally located on extremities, especially hands and wrists. Often resolves after 1-2 years. Topical and/or intralesional corticosteroids.

  • Granuloma annulare: Non-scaling annular plaque on distal extremities. Sometimes confused with tinea corporis (scaling) due to raised borders. Does not require treatment, but may respond to topical and/or intralesional corticosteroids.

Raised

Fluid-filled

• Urticaria (edematous wheal)

  • Etiologies: Autoimmune response, hypersensitivity (drugs/stings/bites), physical stimuli (temperature/pressure/sunlight)

  • Treatment options: H1 blocker (e.g. cimetidine), H2 blocker (e.g. ranitidine), and doxepin (blocks H1 and H2 receptors)

• Free fluid

  • Vesicle (< 1cm)

    • Zoster: Painful burning may precede vesicles by 4 to 5 days. Dermatomal distribution and does not cross midline. Valacyclovir 1000 mg TID x 7 days. Topical prednisone and lidocaine for acute pain. Postherpetic neuralgia treatments include capsaicin, tricyclic antidepressants, gabapentin, pregabalin, and sympathetic nerve blocks. Prevention with Shingrix (two-dose series separated by 6 months) for immune-competent adults ≥ 50 years.

    • Rhus contact dermatitis (e.g. poison ivy): Rinse contact site with water before vesicles develop. Intensely pruritic. Treat with calamine lotion, topical corticosteroids, or oral corticosteroids 1 mg/kg (MDD 60 mg) with 14 day taper. Avoid topical benzocaine (aesthetic), topical antihistamines, and antibiotics.

    • Dermatitis herpetiformis: Celiac disease

  • Bulla (> 1 cm)

    • Bullous impetigo

    • Bullous pemphigoid

    • Pemphigus vulgaris

    • Necrotizing fasciitis

  • Pustule (non-serous fluid)

    • Acne: Topical tretinoin 0.025% gel QHS → benzoyl peroxide 10% gel BID → topical erythromycin 2% gel BID → isotretinoin 1 mg/kg/day x 20 weeks

    • Pseudofolliculitis barbae: Inflammatory reaction provoked by short, tightly-curled hairs irritating skin. Discontinue shaving. Resolves within a few months.

    • Folliculitis: Superficial bacterial infection of hair follicles with S. aureus (common) or Pseudomonas (hot tub folliculitis). Apply warm compresses, avoid shaving in affected areas, and prescribe mupirocin if S. aureus is suspected. May coalesce into a carbuncle.

    • Furunculosis (boil)

    • Hidradenitis suppurativa

    • Pilonidal cyst

    • Primary bacterial abscess

Solid

Papule (<1 cm)

• Malignant/Pre-malignant

  • Actinic keratosis

  • Basal cell carcinoma

  • Squamous cell carcinoma

• Flesh colored

  • Warts

  • Molluscum

• Erythematous

  • Acne: Topical tretinoin 0.025% gel QHS → benzoyl peroxide 10% gel BID → topical erythromycin 2% gel BID → isotretinoin

  • Insects and Mites

    • Bed bugs: Erythematous papule 2-5 mm in diameter with central hemorrhagic punctum. Treat bed clothes with insecticides and heat (wash in scalding water). Topical triamcinolone acetonide 0.1% + loratadine 10 mg qd for pruritus.

    • Scabies: Papules formed by a hypersensitivity reaction to mite eggs and feces. Color over bumps with a dark, felt-tipped marker and then clean with an alcohol wipe - superficial markings are removed while ink in burrows remains. Mites sometimes visualized in skin scrapings. Cover lesions with permethrin 5% cream daily and wait 10 hours before washing location. Ivermectin (Soolantra) 1% cream for recalcitrant cases.

  • Lichen planus: See plaques above

• Hyperpigmented

  • Seborrheic keratosis

  • Dermatofibroma

Nodular (> 1 cm) and/or cystic (membranous sac)

• Lipoma

• Epidermal inclusion cyst

• Mucoid cyst

• Ganglion cyst

• Hypertrophic scars