Study Notes on Dermatology and Skin Conditions

Dermatology Notes

Skin Cancers

  • Types of Skin Cancer
      - Basal Cell Carcinoma
      - Squamous Cell Carcinoma
      - Melanoma
      - Tanning, BED (sun exposure criteria) [Consideration in skin cancer development]
Basal Cell Carcinoma (BCC)

  • Overview
      - Most common skin cancer, comprising 80% of cases.
      - Death rate is extremely low (<0.1%); rarely metastasizes (0.55%).
      - Typically arises on sun-exposed skin; 70% occur on the head, especially the nose.

  • Appearance
      - Waxy papules with a central depression.
      - Key features to remember:
        - Pearly appearance (important for exams).
        - Possible erosion or ulceration, often at the center.
        - Frequent bleeding when traumatized.
        - Crusting and raised borders.
        - Telangiectases visible on the surface.
      - Size can range from a few millimeters to several centimeters.

  • Pigmented Basal Cell Carcinoma
      - Features similar to nodular BCC but with dark pigmentation from melanin deposition.
      - Diagnosis confirmed through skin biopsy (shave or punch).

  • Treatment Options
      - Dermatology referral needed for management.
      - Small lesions (<2 cm) may be treated with:
        - Topical 5% imiquimod.
        - Topical fluorouracil.
      - Surgery, primarily Mohs micrographic surgery, is preferred for removal, especially in high-risk areas like the nose.
      - Chemotherapy may be necessary for rare cases with metastasis.

Squamous Cell Carcinoma (SCC)

  • Overview
      - Present risk of metastasis; significant morbidity possible.
      - More common in men than women.
      - Behavior depends on the site of origin, influencing spread patterns and prognosis.
      - Frequently arises from actinic keratosis, which may be prevalent in surrounding areas.

  • Presentation
      - May present as:
        - Red, crusted, or scaly patches.
        - Hard, red papules or non-healing ulcers.
        - Cup-shaped or crater-shaped nodules.
      - Most commonly found on the head and neck, where aggressive treatment may lead to disfigurement.

  • Recent Findings
      - Use of NSAIDs (including aspirin) has been shown to lower the risk of developing cutaneous SCC.
      - Found to reduce risk by 15% (non-aspirin NSAIDs) and 12% (aspirin) in some studies.

  • Management and Treatment Options
      - Options include:
        - Electrodessication and curettage for low-risk cSCC on the trunk or extremities.
        - Mohs micrographic surgery for invasive cases.
        - Radiation therapy as an adjunct to surgery or primary treatment.
        - Oral 5-fluorouracil (5-FU) and EGFR inhibitors for select high-risk patients.
        - Systemic chemotherapy for metastatic cases.

Mohs Surgery

  • Technique
      - Developed by Frederic E. Mohs in the 1930s.
      - Uses precise excision of visible tumors with a margin of normal tissue.
      - Horizontal frozen sections prepared for microscopic evaluation to ensure complete tumor removal.
      - Allows for nearly 100% margin evaluation, minimizing the chance of incomplete excision found in traditional methods.

  • Indications
      - Ideal for SCC needing tissue preservation, ill-defined tumors, recurrent tumors, and high-risk scenarios.

  • Limitations
      - Not suited for large or aggressive SCCs where recurrence risk is high.

Actinic Keratosis (AK)

  • Overview
      - Also termed solar keratosis; prevalent in fair-skinned individuals with significant sun exposure.
      - Commonly located on face, scalp, ears, neck, upper chest, hands, and forearms.
      - Considered a precancerous condition.

  • Presentation
      - Small, rough spots, 2-6 mm in size.   - Typically reddish with rough texture, possible white or yellowish scale on top.
      - Pain upon touch may occur.

  • Specialized Forms
      - Cutaneous horns: thick protrusions from skin surface.
      - Actinic cheilitis: scaling and roughness of lower lip with blurring border.

  • Treatment
      - Topical 5-fluorouracil cream produces inflammation before AKs fall off but may cause discomfort.
      - Imiquimod (Aldara) works similarly by stimulating the immune response.
      - Ingenol mebutate (Picato) is effective for small areas but irritating.
      - Cryosurgery for freezing AKs, with alternatives including scraping or cauterizing.

Melanoma

  • Staging Overview
      - Staging based on thickness and ulceration.
      - Stages include:
        - Stage 0: Intraepithelial (in situ).
        - Stage IA: ≤ 0.8 mm without ulceration.
        - Stage IB: ≤ 0.8-1 mm with ulceration.
        - Stage IIA: 0.8-2 mm without ulceration.
        - Stage IIB: 1.01-2 mm with ulceration.
        - Stage IIC: 2.01-4 mm without ulceration.
        - Stage IIB: 2.01-4 mm with ulceration.
        - Stage III: ≥ 4 mm without ulceration; with ulceration.

  • Common Considerations in Practice
      - Assess extent for treatment options.
      - Rule of thumb for measuring body surface area: back of hand ~1% of total.   - Handle lesions carefully; tetanus shots needed if injuries are present.

Common Skin Infections and Conditions

Folliculitis
  • Inflammation of hair follicles, usually due to bacterial infection (Staph).
  • Hot Tub Folliculitis: caused by Pseudomonas.
  • Appearance: Small, yellow pustules with hair shaft in the center.
  • Treatment: Good hygiene and topical antibiotics recommended.
Pseudofolliculitis Barbae
  • Reaction due to curly hair growing back into the skin, resulting in bumps resembling ingrown hairs.
  • Treatment options include topical antibiotics and steroids if inflammation is present.
Furuncle (Boil)
  • Deep infection of hair follicle extending into dermis or subcutaneous tissue (usually due to Staph or Strep).
  • Symptoms include localized pain, fever, and malaise.
  • Treatment often requires outpatient care, potentially involving MRSA protocols.
Carbuncle
  • A larger, deeper abscess resulting from multiple furuncles.
  • Can present with systemic symptoms (fever/chills).
  • Treatment involves drainage and aggressive antibiotics.
MRSA (Methicillin-Resistant Staphylococcus Aureus)
  • Acquired in the community or healthcare settings.
  • Symptoms: Rash resembling pimples; can turn into deep abscesses.
  • Risk Factors: Recent hospitalization, antibiotic use, sports, sharing personal items.
  • Treatment includes I&D, warm compresses, and possibly antibiotics like Bactrim.
Cellulitis
  • Acute inflammation and infection of the skin, presenting with redness, swelling, warmth, and tenderness around an area of injury.
  • Typically caused by Staph or Strep bacteria.
  • Requires immediate medical attention, especially if affecting facial areas.
Fungal Infections
  1. Tinea Capitis (Scalp ringworm)
       - Requires systemic treatment; topical applications ineffective.
       - Medications include griseofulvin, itraconazole, etc.
  2. Tinea Corporis (Ringworm)
       - Well-defined, scaly circular patches; often confused with eczema.
       - Topical antifungals are primary treatments.
  3. Tinea Pedis (Athlete's Foot)
       - Vesicular rash on soles of feet, treated with antifungal creams and proper foot hygiene.
  4. Tinea Cruris (Jock Itch)
       - Scaly red rash in groin and thigh area; common in humid conditions.
       - Treated with topical antifungal creams.
  5. Tinea Versicolor
       - Mottled skin lesions that do not tan adequately.
       - Treated with topical antifungals or systemic medication in more severe instances.
Toenail Fungus (Onychomycosis)
  • Presents as thickened, discolored nails, more common in toenails due to warm moist environments.
  • Treatment includes oral Lamisil or topical interventions, but recurrence is common.
  • Recommendations include avoiding unnecessary treatments without confirmation via culture or biopsy, and monitoring liver function due to oral antifungal side effects.
Herpes Zoster (Shingles)
  1. Reactivation of Varicella Zoster Virus (VZV).
  2. Epidemics usually benign, but may pose risks.
  3. Warnings:
       - Herpes Zoster Ophthalmicus can lead to blindness; requires immediate hospital admission.
       - Ramsay Hunt syndrome damages facial and auditory nerves; can cause severe complications.
  4. Postherpetic Neuralgia: Pain persisting beyond 1 month after rash resolution, with increased incidence in older populations.
  5. Treatments include pain management (Gabapentin, TCA), antivirals, and steroids.
Herpes Simplex Virus (HSV)
  • Types I and II; presents as vesicular lesions.
  • Characteristic recurrent pattern; lesions resolve in 5-14 days.
  • Treatments involve analgesics for pain and oral antivirals (acyclovir or valacyclovir).
Psoriasis
  • Immune-mediated skin disorder characterized by increased turnover and thickening of epidermis.
  • Common symptoms include thickened silvery scales typically affecting elbows, knees, and feet.
  • Treatment regimens may involve topical steroids, phototherapy, systemic medications (methotrexate, immunosuppressants), or targeted biologics (Humira, Enbrel).
Dermatitis
  1. Atopic Dermatitis:
       - Chronic, often hereditary, characterized by dry, itchy skin in affected areas.
       - Management includes moisturizers and anti-inflammatory treatments.
  2. Contact Dermatitis:
       - Reaction to allergens (e.g., nickel), resulting in itchy rashes.
       - Treatment focuses on avoiding the allergen and use of topical corticosteroids.
Quiz Questions for Self-Assessment
  • Typical scenarios to test knowledge on skin conditions and their differential diagnoses, including actinic keratosis, basal cell carcinoma, squamous cell carcinoma, and others.
Additional Considerations
  • Any skin cancer management strategies or further assessment should follow the guidelines outlined in educational resources provided, ensuring thorough patient evaluation and treatment protocols.