A 62-year-old fair-skinned man from Delhi presents with a slowly enlarging nodule on the left cheek for 8 months. On examination, he has a pearly, translucent nodule with rolled edges and central ulceration. The lesion is firm, non-tender, and measures 1.5 cm. He has a history of prolonged sun exposure due to outdoor occupation. Dermoscopy reveals arborizing vessels and blue-gray ovoid nests. What is the most likely diagnosis?

## Diagnosis: Basal Cell Carcinoma ### Clinical Presentation **Key Point:** The classic presentation of BCC includes a pearly, translucent nodule with rolled edges and central ulceration (rodent ulcer appearance) on sun-exposed skin. ### Diagnostic Features | Feature | BCC | SCC | Melanoma | |---------|-----|-----|----------| | **Appearance** | Pearly, translucent, rolled edges | Scaly, erythematous, indurated | Asymmetric, irregular borders, variegated color | | **Ulceration** | Central ulceration common | Ulceration less common | Rare unless advanced | | **Growth rate** | Slow (months to years) | Faster than BCC | Variable, often rapid | | **Dermoscopy** | Arborizing vessels, blue-gray nests | Keratin, ulceration, dotted vessels | Asymmetric pigmented network, irregular dots | | **Metastasis risk** | <1% (very low) | 5–10% | High, depends on thickness | **High-Yield:** BCC is the most common skin malignancy worldwide. It arises from the basal layer of the epidermis and has an excellent prognosis due to its low metastatic potential. ### Risk Factors 1. Chronic UV exposure (outdoor workers, fair skin) 2. Age >50 years 3. Male predominance (3–4:1) 4. Genetic predisposition (xeroderma pigmentosum, Gorlin syndrome) **Clinical Pearl:** The "rodent ulcer" appearance (pearly nodule with central ulceration and rolled edges) is pathognomonic for BCC and results from central necrosis with peripheral growth. ### Histopathology - Nests and strands of basaloid cells arising from the epidermis - Peripheral palisading of nuclei - Retraction artifact around tumor nests - Intact basement membrane (usually) ### Dermoscopic Findings (High-Yield) - **Arborizing vessels** (tree-like branching pattern) — most specific - **Blue-gray ovoid nests** — aggregates of basaloid cells - **Ulceration and scale** - **Shiny white streaks** (chrysalis appearance in some variants) **Mnemonic:** **ABCDE for BCC dermoscopy** — Arborizing vessels, Blue-gray nests, Chrysalis appearance, Depressed center, Erosion/ulceration. ### Management 1. **Surgical excision** — gold standard (Mohs micrographic surgery for high-risk lesions) 2. **Curettage and cautery** — for small, low-risk lesions 3. **Topical imiquimod or 5-FU** — for superficial BCC or field cancerization 4. **Radiotherapy** — for elderly patients or those unfit for surgery **Key Point:** BCC has excellent prognosis with >95% 5-year survival after appropriate treatment. Metastases are rare (<1%).