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In this episode of the Physician Assistant Exam Review Podcast, we walk through the “Do I worry?” side of derm: how to quickly sort benign vs concerning skin lesions using pattern recognition, not panic.
Instead of memorizing every lesion in isolation, you’ll learn to organize them into buckets you’ll actually see on exams and in clinic:
- Keratotic lesions: Actinic keratosis vs seborrheic keratosis – rough “sandpaper” vs waxy “stuck‑on,” and when premalignant SCC risk should be on your radar
- Vascular lesions: Cherry angioma, infantile hemangioma, purpura, and telangiectasias – which ones are harmless dots and which should make you think platelets or systemic disease
- Benign soft tissue growths: Lipoma vs epidermal inclusion cyst – the “soft, rubbery, freely mobile” mass patterns and why the central punctum matters
- Chronic inflammatory lesions that mimic infection: Hidradenitis suppurativa – why recurrent “boils” in the axilla/groin aren’t just another abscess
By the end, you’ll be able to answer:
- Recurrent abscesses in the axillae or groin – what diagnosis?
- Rough, scaly, sandpaper‑like lesion on sun‑exposed skin – what diagnosis?
- Waxy, stuck‑on pigmented lesion in an older adult – what diagnosis?
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Keratotic Lesions
Keratotic lesions are defined by abnormal thickening of the stratum corneum, producing a rough, scaly texture that is often felt more than seen. They are commonly found on chronically sun-exposed skin and raise the outpatient question of benign change versus premalignant risk.
Actinic Keratosis
- Premalignant keratinocyte lesion caused by chronic UV exposure
- Defined by abnormal thickening of the stratum corneum producing a rough, scaly surface
- Serves as a risk factor for squamous cell carcinoma
Clinical Presentation
- Rough, scaly, erythematous papule or thin plaque with classic sandpaper texture
- Found on sun-exposed areas such as face, scalp, ears, forearms, and hands
- Often easier to feel than see
- The question stem will sound like:
- An older outdoor worker whose spouse notices a rough patch on the ear or scalp that feels like sandpaper
- A 72-year-old farmer comes into the office
- A 68-year-old roofer comes into the office
Diagnostics
- Clinical diagnosis
- Biopsy if lesion is thickened, ulcerated, bleeding, rapidly growing, or nonhealing to rule out SCC
Treatment
- First-line: Cryotherapy with liquid nitrogen
- Field therapy: Topical 5-fluorouracil or imiquimod for multiple lesions or diffuse sun damage
Exam Keys
- Rough, scaly lesion on sun-exposed skin in an older patient equals actinic keratosis
- Premalignant lesion means think SCC risk, not melanoma
Seborrheic Keratosis
- Benign epidermal proliferation characterized by hyperkeratosis and acanthosis
- No malignant potential
- Commonly seen in older adults
Clinical Presentation
- Waxy, verrucous, well-circumscribed papule or plaque with classic stuck-on appearance
- Color ranges from tan to dark brown or black
- Common on trunk, face, and extremities but spares palms and soles
- Usually asymptomatic, may become pruritic or irritated
- The question stem will sound like:
- An older patient comes in for something unrelated and casually points out a dark, raised spot on their back that looks like it was stuck on with glue
Diagnostics
- Clinical diagnosis
- Biopsy only if atypical appearance, rapid change, bleeding, or diagnostic uncertainty
Treatment
- Reassurance only if asymptomatic
- Cryotherapy, curettage, or shave removal if irritated or for cosmetic reasons
Exam Keys
- Waxy, stuck-on lesion in an older adult equals seborrheic keratosis
- Benign lesion with no malignant transformation
Key Differentiators: Keratotic Lesions
- Actinic keratosis: rough, scaly, sandpaper texture, sun-exposed skin, premalignant, think SCC risk
- Seborrheic keratosis: waxy, stuck-on, well-circumscribed, variable pigmentation, benign, no malignant potential
- Feel versus look matters: actinic keratosis is often felt more than seen, seborrheic keratosis is seen immediately
- Flat versus raised: actinic keratosis is flat or thin, seborrheic keratosis is raised and pasted on
- Exam shortcut: rough plus sun exposure equals actinic; waxy plus stuck on equals seborrheic
Vascular Lesions
- Lesions arising from blood vessels
- Typically present as red, purple, or blue changes
- Outpatient question is whether this represents a benign vascular proliferation or a clue to systemic disease or bleeding risk
Cherry Angioma
- Benign vascular proliferation of capillaries
- Extremely common with aging
- No malignant potential
Clinical Presentation
- Bright red to purple, round papule with smooth surface
- Typically small and well circumscribed
- Common on trunk and extremities
- Asymptomatic and often noticed incidentally
- The question stem will sound like:
- A patient comes in for something else and casually asks about small, bright red dots on their torso that have slowly appeared over time
Diagnostics
- Clinical diagnosis
- No labs or imaging needed
Treatment
- Reassurance only
- Removal with laser or electrocautery for cosmetic reasons or recurrent bleeding
Exam Keys
- Bright red papules in an adult equal cherry angiomas
- Benign finding with no workup required
Hemangioma
- Benign vascular tumor most commonly seen in infants
- Caused by proliferation of capillaries
- Characteristic pattern of early growth followed by spontaneous involution
Clinical Presentation
- Bright red, raised lesion known as strawberry hemangioma
- Deep bluish lesion if subcutaneous
- Appears within the first weeks of life
- Enlarges during infancy, then gradually involutes
- Common on head, neck, and trunk
- Usually asymptomatic, but may ulcerate or bleed if traumatized
- The question stem will sound like:
- A newborn or young infant with a red raised lesion that has grown rapidly over the first few months of life
Diagnostics
- Clinical diagnosis
- Imaging only if deep, segmental, or associated with complications
Treatment
- Observation for most lesions due to spontaneous regression
- Oral propranolol for large, function-threatening, or ulcerated hemangiomas
- Topical beta blockers for small superficial lesions
Exam Keys
- Infant plus red vascular lesion that grows then involutes equals hemangioma
- Most resolve without intervention
Purpura
- Nonblanching discoloration of the skin due to extravasation of blood
- Reflects vessel fragility, platelet disorders, anticoagulation, or systemic disease
- Not a true vascular growth
- Stop and think platelet problem, anticoagulation, or systemic disease
Clinical Presentation
- Purple or red macules or patches that do not blanch with pressure
- May be palpable or nonpalpable
- Common on dependent areas, especially lower extremities
- Associated with medications such as warfarin, DOACs, aspirin, clopidogrel, and chronic steroid use
- Associated with platelet abnormalities such as thrombocytopenia or platelet dysfunction
- The question stem will sound like:
- An older patient on blood thinners or with a recent illness who develops new purple patches on the arms or legs that do not fade when pressed
Diagnostics
- Clinical recognition first
- Evaluate platelet count and coagulation studies when unexplained or concerning
Treatment
- Treat the underlying cause
- Adjust or stop offending medications when appropriate
- Manage platelet or systemic disorders as indicated
- Supportive care for uncomplicated cases
Exam Keys
- Nonblanching lesions equal purpura
- Think bleeding or platelet problem, not vascular growth
Telangiectasia
- Dilated superficial blood vessels visible on the skin or mucosa
- Typically benign
- Important as a possible clue to underlying systemic disease
Clinical Presentation
- Fine red or pink linear vessels that blanch with pressure
- Common on face, lips, oral mucosa, hands, and sun-exposed areas
- Usually isolated and benign
- Multiple lesions should prompt consideration of systemic disease
- Often asymptomatic
- The question stem will sound like:
- A patient with visible red lines on the face or lips that blanch when pressed, often mentioned as an aside
Associations
- Chronic sun exposure and aging
- Rosacea
- Chronic liver disease or estrogen excess
- Hereditary hemorrhagic telangiectasia when recurrent epistaxis or family history is present
Diagnostics
- Clinical diagnosis
- Further workup only if systemic symptoms or concerning associations are present
Treatment
- Reassurance if isolated and asymptomatic
- Laser therapy for cosmetic reasons
- Treat underlying condition when associated with systemic disease
Exam Keys
- Blanching linear red vessels equal telangiectasia
- Isolated lesions are benign; clustered lesions with symptoms suggest systemic disease
Vascular Lesions: Key Differentiators
- Cherry angioma versus purpura: blanching bright red papules versus nonblanching purple patches
- Cherry angioma versus telangiectasia: round papules versus fine linear vessels
- Hemangioma versus cherry angioma: infant lesion that grows then involutes versus adult-onset stable red papules
- Telangiectasia versus purpura: blanches with pressure versus does not blanch
Benign Soft Tissue Growths
- Slow-growing, noninflammatory masses arising from subcutaneous tissue or skin appendages
- Typically painless and benign
- Exam question focuses on whether the lesion is harmless or needs further workup
Lipoma
- Benign tumor of adipose tissue
- Soft, mobile, painless subcutaneous mass
- No malignant potential
Clinical Presentation
- Soft, rubbery, freely mobile mass under the skin
- Painless and slow growing
- Common on trunk, shoulders, neck, and proximal extremities
- Skin overlying the lesion appears normal
- The question stem will sound like:
- A patient notices a soft lump under the skin that moves easily when pushed and has been slowly growing for years
Diagnostics
- Clinical diagnosis
- Imaging or biopsy only if atypical features are present such as rapid growth, firmness, fixation, or pain
Treatment
- Reassurance only if asymptomatic
- Surgical excision if painful, enlarging, or cosmetically bothersome
Exam Keys
- Soft, mobile, painless mass equals lipoma
- Benign lesion with no malignant transformation
Epidermal Inclusion Cyst
- Benign cyst formed from trapped keratin within the epidermis
- Arises from hair follicles
- Commonly mistaken for an abscess or lipoma
Clinical Presentation
- Firm, round, subcutaneous nodule with a central punctum
- Slow growing and usually painless
- Common on face, neck, trunk, and upper back
- May become tender, erythematous, or fluctuant if inflamed or infected
- The question stem will sound like:
- A patient with a long-standing lump under the skin that occasionally becomes red and painful and has a small central opening
Diagnostics
- Clinical diagnosis
- No imaging needed unless diagnosis is uncertain
Treatment
- Reassurance if asymptomatic
- Complete surgical excision including the cyst wall for definitive treatment
- Incision and drainage only if acutely inflamed or infected, with expectation of recurrence
Exam Keys
- Central punctum plus firm cyst equals epidermal inclusion cyst
- Incision and drainage alone does not cure it
