A 55-year-old immunocompromised patient (CD4 count 180 cells/μL, on antiretroviral therapy) presents with a 1.5 cm indurated, hyperkeratotic nodule on the lower lip with a history of rapid growth over 3 weeks. Incisional biopsy shows poorly differentiated squamous cell carcinoma with evidence of lymphovascular invasion and perineural invasion. Clinical examination reveals no palpable cervical lymph nodes. What is the most appropriate next step in management?

Explanation

## Management of High-Risk Cutaneous SCC ### Lesion Risk Stratification **Key Point:** This patient's SCC is **HIGH-RISK** due to multiple adverse features: - **Poorly differentiated histology** (aggressive biological behaviour) - **Lymphovascular invasion** (increased metastatic potential) - **Perineural invasion** (strong predictor of recurrence and regional spread) - **High-risk anatomical site** (lower lip — perioral region with rich lymphatic drainage) - **Immunocompromised host** (HIV with low CD4 count — increased risk of aggressive disease and treatment failure) - **Rapid growth trajectory** (3 weeks) ### Surgical Approach for High-Risk SCC | Feature | Low-Risk SCC | High-Risk SCC | |---------|-------------|---------------| | **Surgical technique** | Conventional WLE (4–6 mm) | Mohs micrographic surgery | | **Margin assessment** | Frozen section | Intraoperative margin mapping | | **Perineural invasion** | Absent | Present → requires wider excision | | **Lymph node assessment** | Clinical exam | Elective neck dissection (if regional nodes at risk) | | **Adjuvant therapy** | Rarely needed | Consider if high-grade, PNI, or inadequate margins | **High-Yield:** Mohs micrographic surgery is the **gold standard** for high-risk SCC because it: 1. Provides real-time histological assessment of all surgical margins 2. Maximizes tissue preservation in critical sites (lips, face) 3. Reduces recurrence rates in poorly differentiated and PNI-positive tumours 4. Allows staged excision with immediate margin feedback ### Elective Neck Dissection Rationale **Clinical Pearl:** Patients with high-risk SCC (especially with perineural invasion, lymphovascular invasion, or poorly differentiated histology) in high-risk sites (lip, ear) have a **15–30% risk of occult regional lymph node metastasis** despite clinically negative nodes. Elective neck dissection (or sentinel lymph node biopsy in selected cases) is recommended. In this case, **elective neck dissection** is more appropriate than sentinel node biopsy because: - Perineural invasion is present (strong predictor of nodal involvement) - Poorly differentiated histology (higher metastatic risk) - Perioral site with predictable lymphatic drainage - Immunocompromised host (may have impaired immune response to tumour antigens, affecting sentinel node identification) ### Why Other Options Are Suboptimal **Warning:** Sentinel lymph node biopsy is less reliable in immunocompromised patients and in the presence of perineural invasion. Systemic chemotherapy is not first-line for resectable cutaneous SCC; it is reserved for unresectable, metastatic, or recurrent disease. Radiation therapy alone is not standard for resectable primary SCC and offers inferior local control compared to surgery. [cite:Robbins 10e Ch 25; NCCN Cutaneous Squamous Cell Carcinoma Guidelines 2023]