Dermatology Flashcards part 1

Basic Skin Terminology

• Macule:
  • Small, typically < 1 cm.
  • Nonpalpable, flat lesion.
  • Varies in color from surrounding tissue (e.g., freckle).
• Patch:
  • Flat lesion, different color than surrounding area.
  • Larger than 1 cm (e.g., port wine stain).
• Papule:
  • Palpable lesion < 1 cm.
  • Solid or cystic (e.g., mole, acne lesion).
• Plaque:
  • Larger than 1 cm (e.g., psoriasis).
• Vesicle:
  • Fluid-filled papule < 1 cm (e.g., herpes zoster/shingles).
• Bulla:
  • Fluid-filled lesion > 1 cm (e.g., bullous impetigo, burn blisters).
• Pustule:
  • Raised papule filled with pus (e.g., acne, folliculitis).
• Nevi/Moles:
  • Proliferation of melanocytes.
  • Concern for melanoma development.
• Exanthem:
  • Widespread, sudden rash.
  • Often associated with viral infections.

Lesion Shape

• Annular:
  • Ring-shaped.
  • Texture or color shift on the edge compared to the center (e.g., tineas).
• Nummular/Discoid:
  • Coin-shaped.
  • Same shape and texture across the lesion.
• Linear:
  • In a straight line.

Adjectives

• Erythematous:
  • Red and inflamed.
• Morbilliform:
  • Measles-like rash.
• Maculopapular:
  • Reddened rash with both flat and palpable areas.

Tick-Borne Illnesses

Lyme Disease

• Keywords: Tick bite, bull's-eye/target-shaped lesion (erythema migrans).
• Early treatment prevents neurological sequelae.
• Treatment:
  • First-line: Doxycycline or vivomycin.
  • Pregnancy: Amoxicillin (CDC recommendation due to potential fetal bone impacts).

Rocky Mountain Spotted Fever

• Symptoms: High fever, nausea, vomiting, myalgias.
• Rash: Spotted, on hands, wrists, ankles, spreading centrally to arms, legs, trunk (2-6 days after initial symptoms).
• Treatment: Doxycycline (regardless of age or pregnancy status, benefits outweigh risks).
  • High mortality rate if untreated.

Critter Related Conditions

Brown Recluse Spider Bite

• Description: Small sting followed by tender, deep purplish-blue spot with a white halo and erythematous ring (red, white, and blue sign).
  • Systemic symptoms.
• Treatment:
  • Cleansing, cold packs, elevation, NSAIDs for pain.
  • Refer to ED if necrosis or infection is suspected.

Dog/Cat/Human Bites

• Thoroughly clean the wound, assess depth, remove debris/necrotic tissue.
• Tetanus or rabies prophylaxis may be needed.
• Suturing may be necessary (avoid on hands or wounds prone to infection); plastics referral for complex wounds.
• Antibiotic:
  • Dog bites: Amoxicillin-clavulanate (Augmentin).
  • Cat bites have a higher risk of infection (Pasteurella multocida).

Cutaneous Anthrax

• Contact with sheep, goats, cattle, horses, and pigs.
• Presentation: Ulcerated, black, painless lesion (cattle farmer).
• Treatment:
  • Fluoroquinolone (ciprofloxacin or levofloxacin)
  • Tetracycline (doxycycline) if no severe manifestations or systemic involvement.

Other Skin Conditions

Atopic Dermatitis (Eczema)

• Symptoms: Intensely pruritic skin, scaly, xerotic/dry, lichenified/thickened.
• Location: Flexor surfaces (back of knees, antecubital space of arms).
• Atopic Triad: Atopic dermatitis, asthma, allergic rhinitis.
• Commonly manifests in early childhood and persists into adulthood.
• Treatment:
  • Moisturizers, emollients, topical steroids.
  • Avoid triggering substances/fabrics, hot baths, harsh soaps.

Plaque Psoriasis

• Presentation: Well-defined red plaques with silvery scale.
• Location: Elbows, knees, scalp.
• Unique Findings: Nail pitting, onycholysis.
• Clinical Signs:
  • Auspitz sign: Pinpoint bleeding when plaques are scratched/removed.
  • Koebner phenomenon: Trauma to skin leads to plaque formation (linear plaque from scratching).
• Treatment:
  • Limited disease: Topical steroids, vitamin D analogues, emollients, coal tar.
  • Moderate/severe disease: Dermatology referral.

Contact Dermatitis

• Reaction in the shape of the irritant.
• Types:
  • Irritant: Direct contact with irritants (soaps, detergents, perfumes).
  • Allergic: Immune-mediated, reaction after second exposure (metals in jewelry, topical medications).
• Treatment: Topical steroids, avoidance of irritant.

Herpes Zoster (Shingles)

• Reactivation of varicella-zoster virus (chickenpox), primarily in older adults.
• Symptoms: Unilateral burning, stabbing, or throbbing pain prior to rash.
• Rash: Unilateral, across a dermatome, vesicular.
• Treatment: Antivirals (acyclovir) within 72 hours of symptom onset to encourage healing, decrease neuropathic pain, and prevent new lesions.
• In immunocompromised patients, consider antivirals even outside the 72-hour window.
• Ocular Involvement: Immediate referral to ophthalmologist or ED for prompt treatment to prevent permanent vision loss.
• Prevention: Shingrix vaccine (2-dose series) for adults over 50 or adults 18+ with immunocompromising conditions, regardless of prior shingles; avoid during active outbreak.

Urticaria (Hives)

• Presentation: Erythematous, pruritic wheals in various shapes and sizes.
• Causes: Allergens (nuts, antibiotics), physical triggers (pressure from tight clothing).
• Treatment: Antihistamines.
• Safety Concern: Anaphylaxis and angioedema (swelling of deeper tissues potentially blocking airway).
  • Assess for facial/mouth swelling, wheezing, respiratory decline; call 911 if anaphylaxis is suspected.