Dermatological Disorders: Lesions, Skin Cancers, Infections & Rash Evaluation
Key Takeaways
- Melanoma screening follows the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolving size/shape/color), with full-thickness excisional biopsy required for suspicious lesions.
- Non-melanoma skin cancers include Basal Cell Carcinoma (pearly papule with telangiectasias and central ulceration/rolled border) and Squamous Cell Carcinoma (scaly, hyperkeratotic papule/nodule with ulceration, precursor actinic keratosis).
- Bacterial skin infections differentiate Cellulitis (non-demarcated, deep dermis/subcutaneous tissue; treated with cephalexin or TMP-SMX/doxycycline if MRSA suspected) from Erysipelas (sharply demarcated, upper dermis; treated with penicillin/amoxicillin).
- Herpes Zoster (Shingles) presents with dermatomal painful vesicular rash; early oral antiviral therapy (valacyclovir/acyclovir within 72 hours) reduces post-herpetic neuralgia risk, and Shingrix (RZV) vaccine is recommended for adults >=50.
- Dermatological evaluation in geriatrics must account for age-related skin changes (xerosis, senile purpura, actinic keratoses) and high risk of pressure injuries evaluated via the Braden Scale.
Dermatological Disorders: Lesions, Skin Cancers, Infections & Rash Evaluation
1. Premalignant & Malignant Skin Lesions
Skin cancers are the most common malignancies in the United States. Differentiating benign, premalignant, and malignant lesions is a critical APRN competency.
Actinic Keratosis (AK)
Actinic keratosis is a premalignant lesion caused by chronic ultraviolet (UV) radiation, carrying a 5%–10% risk of progression to Squamous Cell Carcinoma (SCC). Lesions present as small (2–6 mm), rough, hyperkeratotic, sandpaper-like papules on sun-exposed skin (scalp, face, forearms). Treatment includes cryotherapy with liquid nitrogen for isolated lesions, or field therapy with topical 5-Fluorouracil (5-FU 5%) cream for multiple lesions.
Basal Cell Carcinoma (BCC)
Basal cell carcinoma is the most frequent skin cancer, originating from epidermal basal cells. It is slow-growing and rarely metastasizes. The classic presentation is a pearly, translucent papule with telangiectasias, rolled borders, and central ulceration ("rodent ulcer"). Diagnosis is confirmed via shave or punch biopsy. Treatment includes surgical excision, electrodessication and curettage (ED&C), or Mohs micrographic surgery for facial lesions.
Squamous Cell Carcinoma (SCC)
Squamous cell carcinoma arises from keratinocytes and is the second most common skin cancer. SCC carries a risk of regional lymph node metastasis (especially on ears, lip, or in immunocompromised patients). Lesions present as firm, erythematous, scaly, hyperkeratotic papules or nodules with central ulceration or crusting, often arising from pre-existing actinic keratoses. Biopsy confirmation is required, followed by surgical excision or Mohs surgery.
Malignant Melanoma
Melanoma is the most lethal cutaneous malignancy. Prognosis correlates directly with Breslow depth of invasion (millimeters from epidermal granular layer). Evaluation utilizes the ABCDE Criteria:
- A – Asymmetry: Half of lesion does not match the other.
- B – Border: Irregular, notched, or scalloped borders.
- C – Color: Varied shades of brown, black, red, white, or blue.
- D – Diameter: >6 mm.
- E – Evolving: Changes in size, shape, color, or symptoms.
- The "Ugly Duckling" Sign: A mole that looks distinctly different from others. Biopsy Protocol: Suspicious lesions require a full-thickness excisional biopsy with 1–3 mm margins. Partial shave or punch biopsies of suspected melanoma should be avoided to prevent inaccurate Breslow depth staging.
2. Bacterial & Viral Cutaneous Infections
Bacterial Infections: Cellulitis vs. Erysipelas vs. Abscess
- Cellulitis: Non-necrotizing infection of deep dermis and subcutaneous tissue caused by Streptococcus pyogenes or Staphylococcus aureus. Features localized erythema, warmth, edema, and tenderness with ill-defined, non-demarcated borders. Purulent cellulitis suggests MRSA.
- Management: Non-purulent cellulitis is treated with oral cephalexin (500 mg QID) for 5–7 days. If MRSA is suspected (purulent drainage, prior MRSA), use oral trimethoprim-sulfamethoxazole (TMP-SMX DS BID) or doxycycline (100 mg BID).
- Erysipelas: Superficial infection involving upper dermis and lymphatics, caused by Group A Streptococcus. Presents with sudden fever and a bright red, raised plaque with sharply demarcated borders. Treated with oral penicillin V or amoxicillin.
- Cutaneous Abscess: Fluctuant erythematous nodule containing pus. Primary treatment is incision and drainage (I&D). Antibiotics are added if systemic signs or immunocompromised.
Viral Infection: Herpes Zoster (Shingles)
Herpes Zoster results from latent Varicella-Zoster Virus (VZV) reactivation in sensory ganglia.
- Presentation: Unilateral burning dermatomal pain followed by clustered erythematous papules and vesicles along a single dermatome (does not cross midline).
- Complications: Post-Herpetic Neuralgia (PHN; neuropathic pain >=90 days post-rash). Herpes Zoster Ophthalmicus (HZO) involves CN V1; vesicles on tip of nose (Hutchinson's sign) indicate ocular involvement requiring immediate urgent ophthalmology consult.
- Management: Oral valacyclovir (1,000 mg TID) within 72 hours of rash onset shortens duration and reduces PHN. Prevention: Recombinant Zoster Vaccine (Shingrix) 2-dose series for adults >=50 years.
3. Inflammatory Rashes & Dermatoses
Contact Dermatitis
- Irritant: Direct toxic damage from soaps/solvents.
- Allergic: Type IV delayed hypersensitivity (poison ivy/urushiol, nickel) causing severe pruritus and linear streaks of vesicles.
- Treatment: High-potency topical steroids (triamcinolone); for severe cases (>20% BSA), prescribe an oral prednisone taper over 14–21 days.
Seborrheic Dermatitis
Inflammatory reaction to Malassezia yeast. Presents with greasy, yellow scales on erythematous plaques on scalp, eyebrows, and nasolabial folds (common in Parkinson's and HIV). Treated with topical ketoconazole 2% shampoo/cream and mild steroids.
Psoriasis Vulgaris
Autoimmune T-cell disease causing well-demarcated erythematous plaques with thick silvery-white scales on extensor surfaces (elbows, knees). Features Auspitz sign (pinpoint bleeding when scale scraped) and Koebner phenomenon (lesions at trauma sites). Treated with topical corticosteroids, calcipotriene, phototherapy, or systemic biologics.
4. Geriatric Dermatology & Pressure Injuries
Age-Related Changes
Xerosis (dry skin causing pruritus), Senile Purpura (purple macules on forearms from minor capillary trauma), and Seborrheic Keratoses (benign "stuck-on" waxy papules).
Pressure Injury Staging (NPIAP Criteria & Braden Scale <=15)
- Stage 1: Intact skin with localized non-blanchable erythema.
- Stage 2: Partial-thickness skin loss with exposed dermis (shallow ulcer or intact/ruptured serum blister; no fat visible).
- Stage 3: Full-thickness loss; subcutaneous fat is visible, but no bone, tendon, or muscle exposed.
- Stage 4: Full-thickness loss with exposed bone, tendon, muscle, or cartilage.
- Unstageable: Full-thickness loss covered by slough/eschar. Stable dry eschar on heels should NOT be debrided.
- Deep Tissue Pressure Injury (DTPI): Persistent non-blanchable deep red, maroon, or purple discoloration.
Diagnostic & Practice Matrix
| Condition | Clinical Hallmark | Diagnostic Method | First-Line Treatment |
|---|---|---|---|
| Basal Cell Carcinoma | Pearly papule, telangiectasias, rolled border | Punch/shave biopsy | Excision or Mohs surgery |
| Squamous Cell Carcinoma | Scaly hyperkeratotic nodule, ulceration | Punch/shave biopsy | Excision or Mohs surgery |
| Malignant Melanoma | Asymmetric, color variation, evolving | Full-thickness excisional biopsy | Wide local excision, Breslow staging |
| Erysipelas | Bright red raised plaque, sharply demarcated | Clinical diagnosis | Oral Penicillin V or Amoxicillin |
| Herpes Zoster | Unilateral dermatomal vesicular rash | Clinical / PCR | Valacyclovir within 72h; Shingrix vaccine |
| Stage 3 Pressure Injury | Subcutaneous fat visible; no exposed bone/muscle | Clinical / Braden scale | Debridement, moisture control, pressure relief |
An APRN evaluates a 64-year-old male with a suspicious lesion on his upper back. The lesion is asymmetric, 8 mm in diameter, with irregular notched borders and variable shades of dark brown and black. The patient states it has grown noticeably larger over the past 4 months. What is the most appropriate initial diagnostic procedure?
A 76-year-old female presents with a 2-day history of burning pain on the right side of her forehead, followed by the appearance of clustered fluid-filled vesicles on an erythematous base. Physical examination reveals vesicles located on the tip of her nose (Hutchinson's sign). What is the priority intervention for this patient?
A 70-year-old male residing in a long-term care facility is evaluated for a sacral wound. Physical examination reveals a deep open ulcer with visible subcutaneous fat. Granulation tissue is present, but no muscle, tendon, or bone is exposed. How should the APRN stage this pressure injury?
A 52-year-old female presents with a 3-day history of a rapidly spreading, hot, tender, bright red skin eruption on her right lower leg. The lesion has prominent, raised, sharply demarcated borders separating infected from uninfected skin. She has a temperature of 101.4°F. What is the most likely diagnosis and appropriate initial treatment?