A 72-year-old woman with a history of chronic actinic keratosis presents with a 1.5 cm × 1.2 cm indurated, scaly plaque on the right temple with recent rapid growth over 3 months. She has fair skin and a 50-year history of sun exposure. Dermoscopy reveals a hyperkeratotic plug with irregular vascular pattern. Histopathology shows well-differentiated squamous cell carcinoma with invasion limited to the dermis (depth 2.5 mm), no perineural invasion, and clear surgical margins. Regional lymph nodes are not palpable. What is the most appropriate next step in management?

Explanation

## Management of Low-Risk Cutaneous Squamous Cell Carcinoma ### Risk Stratification of This Lesion | Risk Factor | Status in This Patient | Risk Category | |-------------|------------------------|---------------| | **Size** | 1.5 cm (< 2 cm) | Low-risk | | **Depth of invasion** | 2.5 mm (< 4 mm) | Low-risk | | **Differentiation** | Well-differentiated | Low-risk | | **Perineural invasion** | Absent | Low-risk | | **Margins** | Clear | Low-risk | | **Regional lymphadenopathy** | Absent | Low-risk | | **Location** | Temple (face) | Intermediate-risk (but other factors favorable) | **Key Point:** This is a **low-risk SCC** by all major criteria (AAD, NCCN, Brigham and Women's Hospital). The combination of small size, shallow depth, well-differentiation, clear margins, and absent lymphadenopathy indicates excellent prognosis with local excision alone. ### Management Algorithm for Cutaneous SCC ```mermaid flowchart TD A["Cutaneous SCC diagnosed"]:::outcome --> B{"Risk stratification"}:::decision B -->|"Low-risk (size <2cm, depth <4mm,\nwell-differentiated, no PNI,\nclear margins, no lymphadenopathy)"|C["Surgical excision alone<br/>(standard or Mohs)"]:::action B -->|"High-risk (size >2cm, depth >4mm,\npoor differentiation, PNI present,\nor lymphadenopathy)"|D["Wide local excision or Mohs"]:::action D --> E{"Lymph node involvement?"}:::decision E -->|"Yes"|F["Consider SLNB, lymphadenectomy,<br/>adjuvant radiation, or systemic therapy"]:::action E -->|"No"|G["Close clinical follow-up"]:::action C --> H["Follow-up: clinical exam<br/>every 3-6 months × 2 years"]:::action H --> I["Then annual surveillance"]:::outcome ``` ### Why Observation with Clinical Follow-Up is Correct 1. **Low-risk features** — all major adverse prognostic factors are absent 2. **Clear margins achieved** — no residual disease 3. **No nodal involvement** — no evidence of metastatic disease 4. **Excellent prognosis** — 5-year recurrence rate <5% for low-risk SCC 5. **Standard of care** — AAD and NCCN guidelines recommend observation alone for low-risk SCC with clear margins **Clinical Pearl:** The key distinction is that this patient has **already undergone appropriate surgical excision with clear margins**. The question is now about follow-up management, not initial treatment. For low-risk SCC with clear margins, observation with regular clinical surveillance is the standard approach. **High-Yield:** The **American Academy of Dermatology (AAD) guidelines** define low-risk SCC as: - Size < 2 cm - Depth < 4 mm (Clark level ≤ III) - Well or moderately differentiated - No perineural invasion - Clear surgical margins - No clinical lymphadenopathy For low-risk SCC, **observation alone is appropriate** if margins are clear. ### Follow-Up Schedule - **Every 3 months** for the first 2 years (to detect early recurrence) - **Every 6 months** for years 2–5 - **Annually** thereafter [cite:American Academy of Dermatology SCC Guidelines; NCCN Cutaneous Melanoma and Non-Melanoma Skin Cancer Guidelines]