# Clinical Cases: Dermatology in Primary Care

## Case 1: Psoriasis

### Patient Demographics
- **Age:** 35 years old
- **Sex:** Male
- **Occupation:** Sales representative

### Chief Complaint
"I have these red, scaly patches on my elbows and knees that won't go away. They're embarrassing."

### History of Present Illness
Mr. Christopher Adams is a 35-year-old man presenting with a 6-month history of red, scaly patches on his elbows, knees, and lower back. The patches are mildly itchy but mostly a cosmetic concern. He first noticed small patches on his elbows that gradually enlarged and spread. He has tried over-the-counter hydrocortisone with minimal improvement. He reports the skin flakes onto his dark clothing, which he finds embarrassing at work. He recently noticed similar changes on his scalp with flaking. No joint pain or swelling.

He reports increased stress at work recently, and symptoms seem to worsen during stressful periods.

### Past Medical History
- No chronic medical conditions
- No prior skin conditions

### Family History
- Father: Psoriasis
- Mother: Type 2 diabetes
- No family history of autoimmune diseases

### Social History
- Social drinker (3-4 beers on weekends)
- Non-smoker
- Single, lives alone
- High-stress job with frequent travel

### Physical Examination
- **Vital Signs:** BP 124/78 mmHg, HR 72, BMI 27
- **General:** Well-appearing male, mildly overweight
- **Skin:**
  - Bilateral elbows: Well-demarcated, erythematous plaques with thick, silvery-white scale, 3-5 cm
  - Bilateral knees: Similar plaques, 2-4 cm
  - Lower back: One plaque, 4 cm
  - Scalp: Erythematous patches along hairline with white scale
  - Auspitz sign positive (pinpoint bleeding with scale removal)
  - Nails: Pitting on several fingernails, no onycholysis
  - No involvement of face, palms, soles, or groin
- **Musculoskeletal:** No joint swelling, tenderness, or deformity
- **Body Surface Area (BSA) involved:** Approximately 4%

### Clinical Image
![Psoriasis plaques on back](case_01_image.jpg)

*Image: Psoriatic plaques demonstrating characteristic features including well-demarcated erythematous plaques with silvery-white scale, commonly seen on extensor surfaces and lower back.*

**Image Source:** Wikimedia Commons
**Attribution:** Eisfelder, CC BY-SA 3.0
**URL:** https://commons.wikimedia.org/wiki/File:Psoriasis_on_back1.jpg

### Assessment and Diagnosis
1. **Plaque psoriasis, mild-moderate** - Classic presentation with well-demarcated erythematous plaques with silvery scale on extensor surfaces
2. **Scalp psoriasis** - Common extension
3. **Nail psoriasis** - Pitting indicative of psoriatic nail involvement
4. **No current psoriatic arthritis** - Important to screen given nail involvement (risk factor)

### Management Plan

**Topical Therapy (First-line for Limited Disease):**
- High-potency topical corticosteroid: Betamethasone dipropionate 0.05% ointment BID to body plaques
  - Limit to 2-4 weeks continuous, then use intermittently
- Medium-potency for scalp: Fluocinonide solution for scalp daily
- Calcipotriene (vitamin D analog) 0.005% cream: Apply daily as steroid-sparing agent
- Combination product: Calcipotriene/betamethasone dipropionate foam - once daily, effective and well-tolerated

**For Scalp:**
- Tar-based shampoo (OTC) 2-3 times weekly
- Leave-on scalp treatments: Fluocinonide solution or clobetasol foam
- Calcipotriene scalp solution

**For Nail Psoriasis:**
- Difficult to treat topically
- Monitor for progression
- May improve with systemic therapy if needed in future

**Lifestyle Modifications:**
- Stress management (psoriasis flares with stress)
- Weight loss (obesity associated with more severe psoriasis)
- Limit alcohol (can worsen psoriasis and interfere with some treatments)
- Smoking cessation counseling (he doesn't smoke, but confirm)
- Moisturize frequently (reduces scale, improves barrier)

**Screening Considerations:**
- Monitor for psoriatic arthritis at each visit (PASE questionnaire)
- Screen for metabolic syndrome (obesity, hypertension, diabetes, dyslipidemia) - higher risk in psoriasis
- Consider depression screening (high comorbidity)

### Follow-Up
- Return in 6-8 weeks to assess topical response
- If inadequate response (BSA >10%, affecting quality of life), consider:
  - Phototherapy (UVB) - referral to dermatology
  - Systemic therapy (methotrexate, apremilast, biologics) - dermatology referral
- Annual skin cancer screening (if on phototherapy)

### Teaching Points
1. **Psoriasis recognition:** Well-demarcated erythematous plaques with silvery-white scale on extensor surfaces (elbows, knees), scalp, and lower back. Auspitz sign (pinpoint bleeding with scale removal) is characteristic.

2. **Psoriatic arthritis screening:** 30% of psoriasis patients develop psoriatic arthritis. Nail involvement increases risk. Ask about joint pain, stiffness, swelling, and sausage digits (dactylitis).

3. **Treatment approach by severity:**
   - Mild (<5% BSA): Topical therapy (corticosteroids, vitamin D analogs)
   - Moderate (5-10% BSA): Topical + phototherapy or consider systemic
   - Severe (>10% BSA or significant QOL impact): Systemic therapy, biologics

4. **Comorbidities:** Psoriasis is associated with metabolic syndrome, cardiovascular disease, depression, and inflammatory bowel disease. Screen appropriately.

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## Case 2: Suspicious Pigmented Lesion

### Patient Demographics
- **Age:** 58 years old
- **Sex:** Female
- **Occupation:** Golf instructor

### Chief Complaint
"I have a mole on my back that my husband says has changed."

### History of Present Illness
Mrs. Barbara Thompson is a 58-year-old woman presenting because her husband noticed a mole on her upper back that appears to have changed. She cannot see it herself but he reports it has become darker and larger over the past 6 months. She first noticed it about 5 years ago as a small brown spot. She has no symptoms - no itching, bleeding, or pain. She has numerous other moles on her body that have not changed.

She has extensive sun exposure history due to her occupation as a golf instructor for 30 years. She admits to several blistering sunburns as a teenager. She does not regularly use sunscreen.

### Past Medical History
- Hypertension
- History of actinic keratoses (treated with cryotherapy)
- Basal cell carcinoma removed from nose 3 years ago

### Family History
- Mother: Melanoma (age 62, survived)
- Father: Non-melanoma skin cancer
- Sister: Multiple atypical moles

### Social History
- Non-smoker
- Social drinker
- Married
- Golf instructor, extensive outdoor sun exposure
- Lives in Arizona

### Physical Examination
- **Vital Signs:** BP 132/80 mmHg, HR 70, BMI 25
- **Skin - Full Body Examination:**
  - **Lesion of concern (left upper back):**
    - 12 mm pigmented lesion
    - Asymmetric shape
    - Irregular, notched borders
    - Color variation: Brown, dark brown, and black areas
    - Raised area on one side, flat on other
  - Fitzpatrick skin type II (fair skin, burns easily)
  - Numerous (>50) benign-appearing nevi
  - Several atypical nevi on trunk
  - Actinic keratoses on forearms (2)
  - Well-healed scar on nose from BCC excision
- **Lymph nodes:** No palpable cervical, axillary, or inguinal lymphadenopathy

### ABCDE Assessment of Concerning Lesion
- **A - Asymmetry:** Present (one half does not match the other)
- **B - Border:** Irregular, notched, poorly defined
- **C - Color:** Variegated (multiple shades of brown/black)
- **D - Diameter:** 12 mm (>6 mm)
- **E - Evolution:** Changed/enlarged over 6 months per husband

### Assessment and Diagnosis
1. **Suspicious pigmented lesion** - Concerning for melanoma given ABCDE criteria; requires biopsy
2. **Multiple risk factors for melanoma:**
   - Prior melanoma in first-degree relative (mother)
   - History of non-melanoma skin cancer (BCC)
   - Extensive sun exposure
   - Fair skin (Fitzpatrick II)
   - Multiple nevi (>50)
   - History of blistering sunburns
3. **Actinic keratoses** - Precancerous lesions from chronic sun damage
4. **Atypical nevi** - Require monitoring

### Management Plan

**For Suspicious Lesion:**
- **Excisional biopsy** - Gold standard for suspicious pigmented lesion
  - Full-thickness excision with narrow margins (1-2 mm)
  - Send for histopathology
  - Do NOT perform shave biopsy for lesions suspicious for melanoma (need full depth for staging)
- If melanoma confirmed: Wide local excision margins based on Breslow depth, possible sentinel lymph node biopsy, oncology referral

**For Actinic Keratoses:**
- Cryotherapy to two lesions on forearms today
- Discuss field therapy (5-fluorouracil cream) if multiple lesions develop

**Skin Cancer Prevention Counseling:**
- Sun protection: Daily sunscreen SPF 30+, reapply every 2 hours when outdoors
- Protective clothing, wide-brimmed hat
- Avoid peak sun hours (10 AM - 4 PM)
- No tanning beds
- Monthly self-skin exams with partner assistance for back

**Referral:**
- Dermatology referral for full-body skin examination given high-risk features
- Dermatoscopy evaluation of atypical nevi
- Consider baseline total body photography for monitoring

### Follow-Up
- Results of biopsy in 7-10 days
- If melanoma confirmed: Urgent surgical oncology/dermatology for definitive management
- Regular skin surveillance (every 3-6 months given risk factors)

### Teaching Points
1. **ABCDE criteria for melanoma:**
   - **A**symmetry
   - **B**order irregularity
   - **C**olor variation
   - **D**iameter >6 mm
   - **E**volution (change over time)
   - "Ugly duckling sign": Lesion that looks different from patient's other moles

2. **Melanoma risk factors:**
   - Family history of melanoma (2-3x increased risk with first-degree relative)
   - Fair skin, light hair/eyes
   - History of blistering sunburns
   - Multiple nevi (>50)
   - Atypical nevi
   - Prior melanoma or non-melanoma skin cancer
   - Immunosuppression
   - Intense intermittent sun exposure

3. **Biopsy technique:** Excisional biopsy is preferred for lesions suspicious for melanoma to obtain full thickness and assess Breslow depth. Shave or punch biopsies may transect the lesion and compromise staging.

4. **Primary care role:**
   - Perform skin cancer screening in high-risk patients
   - Recognize concerning lesions
   - Perform or refer for biopsy
   - Counsel on sun protection
   - Know when to refer to dermatology