A 72-year-old man with a history of chronic sun exposure presents with a 1.2 cm erythematous, scaly plaque on the left ear helix that has been growing for 6 months. On examination, the lesion is firm, with indistinct borders and surrounding solar elastosis. There is a single firm, mobile lymph node (1.5 cm) in the ipsilateral cervical region. Biopsy confirms moderately differentiated squamous cell carcinoma with invasion into the reticular dermis. Which of the following is the most appropriate next step in management?

Explanation

## Management of High-Risk Cutaneous SCC ### Risk Stratification in This Case **Key Point:** This patient has multiple high-risk features: 1. **Location:** Ear (H-zone) — high-risk anatomical site with increased recurrence and metastasis risk 2. **Depth:** Reticular dermal invasion (Clark IV) — 5–10% metastasis risk 3. **Grade:** Moderately differentiated — intermediate biological aggressiveness 4. **Regional lymphadenopathy:** Suggests nodal involvement (clinical Stage IIIB–IV) ### High-Risk SCC Definition | Feature | Risk Category | |---|---| | Clark IV–V invasion | High-risk | | Poorly differentiated histology | High-risk | | Diameter >2 cm | High-risk | | Location: ear, lip, eyelid, nose | High-risk | | Immunosuppression (transplant, HIV, CLL) | High-risk | | Perineural invasion | Very high-risk | | Regional lymphadenopathy | Advanced disease | ### Recommended Management Algorithm ```mermaid flowchart TD A[High-risk SCC: Clark IV, ear location, regional LN]:::outcome --> B{Surgical approach?}:::decision B -->|Mohs preferred| C[Mohs micrographic surgery]:::action B -->|Mohs unavailable| D[Wide local excision 10-15mm]:::action C --> E{Regional LN involvement?}:::decision D --> E E -->|Yes/Clinically suspicious| F[Sentinel lymph node biopsy]:::action E -->|No| G[Clinical observation q3-6 months]:::action F --> H{Positive nodes?}:::decision H -->|Yes| I[Neck dissection + adjuvant RT]:::action H -->|No| G ``` ### Why Mohs Micrographic Surgery? **High-Yield:** Mohs surgery is the gold standard for high-risk SCC because: - **Margin control:** Real-time histological assessment of 100% of margins (vs. 5–10% in standard excision) - **Tissue preservation:** Removes only tumor-bearing tissue, sparing maximum normal skin - **Recurrence rates:** 1–3% for high-risk SCC vs. 5–15% with standard excision - **Particularly indicated:** Ear, lip, periocular, perineural invasion, recurrent lesions ### Sentinel Lymph Node Biopsy Indications **Clinical Pearl:** SLNB is indicated when: - Clark IV–V invasion with high-grade histology - Clinically suspicious regional lymphadenopathy (as in this case) - Diameter >2 cm with high-risk features - Perineural invasion - Immunosuppressed patients In this patient, the palpable cervical lymph node makes SLNB mandatory to: 1. Confirm nodal involvement 2. Stage the disease accurately (AJCC Stage IIIB vs. IV) 3. Guide adjuvant therapy (radiation ± chemotherapy if nodes are positive) ### Adjuvant Therapy Considerations - **Radiation therapy:** Reserved for: - Positive lymph nodes after SLNB/neck dissection - Perineural invasion - Close/positive margins that cannot be re-excised - Recurrent disease - NOT as primary treatment for resectable disease - **Chemotherapy:** Indicated only for: - Unresectable disease - Distant metastases - Palliative care - NOT for localized high-risk SCC without systemic disease