Squamous Cell Carcinoma vs Actinic Keratosis
Squamous Cell Carcinoma and Actinic Keratosis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Squamous Cell Carcinoma vs Actinic Keratosis at a glance
- Squamous Cell Carcinoma: Second most common skin cancer; UV-driven keratinocyte malignancy with real metastatic potential, especially in immunosuppressed.
- Actinic Keratosis: UV-induced precancerous keratinocyte lesion on sun-damaged skin; ~10% lifetime risk of progression to invasive SCC per lesion.
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Side-by-side comparison
| Feature | Squamous Cell Carcinoma | Actinic Keratosis |
|---|---|---|
| At a glance | Second most common skin cancer; UV-driven keratinocyte malignancy with real metastatic potential, especially in immunosuppressed. | UV-induced precancerous keratinocyte lesion on sun-damaged skin; ~10% lifetime risk of progression to invasive SCC per lesion. |
| Classic presentation | Hyperkeratotic indurated nodule with central ulceration on sun-damaged skin of an older adult, often arising from a pre-existing actinic keratosis.; Often asymptomatic; new growth, non-healing 'sore', or growth in a chronic scar/ulcer; Tenderness, bleeding, crusting; Pain, paresthesia, motor weakness → perineural invasion; Bowen disease… | Gritty sandpaper-textured pink scaly papule on a sun-damaged background of an older fair-skinned adult.; Usually asymptomatic; some lesions tender or pruritic with friction; Sandpaper texture often felt before lesion is seen — diagnostic clue; Patient concern about cosmetic appearance; Rough, scaly, erythematous papule or macule on… |
| Workup / key labs | Histopathologic confirmation; AJCC 8th edition staging + NCCN/BWH risk stratification; Skin biopsy (shave, punch, or excisional) — tissue diagnosis required; Histopathology determines depth, differentiation (well/moderate/poor), perineural invasion, and high-risk features | Clinical: characteristic rough scaly papule on sun-damaged skin of older adult; biopsy if suspicion of SCC.; Clinical diagnosis sufficient for typical lesions; Skin biopsy if atypical features (induration, ulceration, bleeding, rapid growth, >1 cm, tenderness, refractory to therapy) — to exclude invasive SCC; Dermoscopy: strawberry… |
| Imaging | Lymph node ultrasound + FNA if palpable lymphadenopathy or high-risk tumor; CT/MRI for large tumors, perineural invasion symptoms, deep tissue/bone involvement; PET/CT for staging in advanced disease; Sentinel lymph node biopsy considered for high-risk SCC (>2 cm, >6 mm depth, poor differentiation, perineural invasion,… | Not indicated |
| First-line treatment | Low-risk primary cutaneous SCC: surgical excision with 4-6 mm clinical margins (cure rate >95%); Mohs micrographic surgery (preferred for high-risk SCC): face/H-zone, ears, lips, genitalia, perineural invasion, recurrent, >2 cm, depth >6 mm, poor differentiation, immunosuppressed host; ED&C for small (<1 cm) low-risk SCC in situ on… | Lesion-directed therapy for isolated AKs:; • Cryotherapy with liquid nitrogen — 5-10 seconds per lesion; most common; cure ~67-83%; possible hypopigmentation; • Curettage ± electrodessication for hypertrophic or persistent AKs; Field therapy for multiple AKs or field cancerization (preferred when ≥6-10 AKs in an area):; • 5-fluorouracil… |
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