Skin Part 1

Overview of Skin

  • Skin conditions can be difficult to assess due to the reliance on visual observation by clinicians.

  • This guide will cover common skin conditions encountered in exams and clinical practice, along with identification and treatment tools.

Basic Terminology of Skin Lesions

Key Definitions

  • Macule:

    • Definition: A small, nonpalpable skin lesion less than 1 cm, varying in color from surrounding tissue.

    • Example: A freckle.

  • Patch:

    • Definition: A flat skin lesion larger than 1 cm, differing in color from surrounding tissue.

    • Example: A large port wine stain.

  • Papule:

    • Definition: A palpable lesion less than 1 cm, can be solid or cystic.

    • Examples: A mole or an acne lesion.

  • Plaque:

    • Definition: Elevated and often plateaulike lesions greater than 1 cm.

    • Example: Psoriasis plaques.

  • Vesicle:

    • Definition: A fluid-filled papule less than 1 cm.

    • Example: Herpes zoster lesions.

  • Bullae:

    • Definition: Fluid-filled lesions larger than 1 cm.

    • Example: Burn blisters or bullous impetigo.

  • Pustule:

    • Definition: A raised papule filled with pus.

    • Examples: Acne lesions, folliculitis.

  • Nevi (Moles):

    • Definition: Proliferation of melanocytes; important in relation to melanoma risk.

  • Exanthem:

    • Definition: A widespread rash that erupts suddenly, typically associated with viral infections.

Descriptive Terms for Lesions

  • Annular: Wing shaped; characterized by a color or texture change at the lesion edge (e.g., tinea).

  • Nummular (Discoid): Coin shaped lesions with uniform shape and texture.

  • Linear: Lesions that follow a straight line.

  • Erythematous: Red and inflamed skin.

  • Morbilliform: Rash resembling measles.

  • Maculopapular: Rash including both flat (macules) and raised (papules) areas.

Common Skin Conditions

Tick-Borne Illnesses

Lyme Disease

  • Characteristics:

    • Association: Tick bite history; presence of a "bull's eye" or target lesion known as erythema migrans.

    • Treatment: Early intervention with doxycycline or vivomycin; amoxicillin recommended during pregnancy.

Rocky Mountain Spotted Fever

  • Characteristics:

    • Symptoms: High fever, nausea, vomiting, and myalgias followed by a spotted rash appearing on the hands, wrists, and ankles, spreading centrally.

    • Treatment: Treated with doxycycline regardless of patient's age due to high mortality without treatment.

Spider Bites

Brown Recluse Spider Bite

  • Characteristics:

    • Description: Small sting followed by tenderness, deep purplish blue coloration, white halo, and erythematous red ring known as "red, white, and blue sign."

    • Management: Cleansing, cold packs, elevation, and pain relief; refer to emergency care if necrosis or infection is suspected.

Animal Bites

Dog, Cat, and Human Bites

  • Management Steps:

    • Clean the wound thoroughly, assess depth, and remove debris.

    • Consider tetanus or rabies prophylaxis.

    • Avoid suturing on hands or infected-prone areas; refer to plastics if necessary.

  • Antibiotic treatment:

    • Dog bites: Augmentin (amoxicillin-clavulanate).

    • Risk: Cat bites present a higher infection risk due to Pasteurella multisida.

Infectious Conditions

Anthrax

Cutaneous Anthrax

  • Characteristics:

    • Common in cattle farmers; painless ulcerated black lesion.

  • Treatment:

    • Fluoroquinolone (ciprofloxacin, levofloxacin) or tetracycline (doxycycline).

Atopic Dermatitis (Eczema)

  • Description:

    • Itchy, scaly skin on flexor surfaces, associated with scratching leading to lichenification.

  • Atopic Triad:

    • Connection between atopic dermatitis, asthma, and allergic rhinitis.

  • Management:

    • Use moisturizers, emollients, topical steroids; educate on avoiding triggers and irritants.

Plaque Psoriasis

  • Characteristics:

    • Well-defined red plaques with silvery scales; commonly found on elbows, knees, and scalp.

    • Associated signs: nail pitting and onycholysis.

  • Specific Signs:

    • Auspitz sign: Pinpoint bleeding upon plaque removal.

    • Koebner phenomenon: Plaques forming due to skin trauma.

  • Management:

    • Limited disease treated with topical steroids and vitamin D analogs; severe cases referred to dermatology.

Dermatitis Conditions

Contact Dermatitis

  • Types:

    • Irritant contact dermatitis: Limited to contact area.

    • Allergic contact dermatitis: Immune-mediated, requires prior exposure for reaction.

  • Management:

    • Topical steroids and avoidance of irritants.

Viral Conditions

Herpes Zoster (Shingles)

  • Characteristics:

    • Caused by reactivation of varicella zoster virus in older adults; presents with unilateral severe pain preceding a vesicular rash.

  • Management:

    • Antiviral treatment (acyclovir) within 72 hours of symptoms can promote healing and reduce complications.

    • Referral to ophthalmology if lesions are near the eye.

  • Vaccination:

    • Shingrix vaccine: Protects against shingles and should be administered in a two-dose series, regardless of past shingles episodes.

Urticaria (Hives)

  • Characteristics:

    • Erythematous, pruritic wheels in various shapes and sizes, often triggered by allergens or physical stimuli.

  • Management:

    • Antihistamines; monitor for severe symptoms like anaphylaxis or angioedema.

  • Emergency Response:

    • Call 911 for suspected anaphylaxis; patient should not drive themselves to the emergency department.

Conclusion

  • This guide covers various skin conditions with a focus on definitions, signs, symptoms, and treatment protocols relevant for exam preparation and clinical practice. Further detailed study is recommended to fully grasp the complexities of skin pathology and management strategies.