A 68-year-old man from Delhi presents with a slowly enlarging, painless nodule on his left cheek for the past 8 months. On examination, there is a 1.5 cm pearly nodule with a rolled border, central ulceration, and telangiectatic vessels visible on the surface. The lesion has not responded to topical antibiotics. Dermoscopy shows arborizing vessels. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Basal Cell Carcinoma ### Key Clinical Features **Key Point:** The combination of a pearly nodule with a rolled border, central ulceration (rodent ulcer), and telangiectatic vessels is pathognomonic for basal cell carcinoma (BCC). ### Diagnostic Hallmarks | Feature | BCC | SCC | Melanoma | Keratoacanthoma | | --- | --- | --- | --- | --- | | **Border** | Rolled, pearly | Ill-defined, scaly | Irregular, asymmetric | Well-defined, raised | | **Surface** | Telangiectasia, ulceration | Keratinization, crusting | Variegated color | Central keratin plug | | **Growth rate** | Slow (months to years) | Moderate | Variable | Rapid (weeks) | | **Dermoscopy** | Arborizing vessels | Linear vessels | Asymmetric pigment | Concentric rings | | **Age of onset** | >50 years | >60 years | Any age | 50–70 years | **High-Yield:** Arborizing (tree-like branching) vessels on dermoscopy are virtually diagnostic of BCC and distinguish it from other skin cancers. ### Pathophysiology 1. Arises from basal keratinocytes in the epidermis 2. Slow growth with low metastatic potential (<1% metastasis rate) 3. Locally invasive with potential for perineural spread 4. Risk factors: UV exposure, fair skin, age >50 years, immunosuppression **Clinical Pearl:** BCC on the face (especially nose, cheek, forehead) is the most common presentation; the lesion may appear as a "rodent ulcer" with central necrosis and a shiny, rolled border. ### Why This Diagnosis? - **Pearly nodule with rolled border** → classic BCC morphology - **Central ulceration** → "rodent ulcer" appearance, hallmark of nodular BCC - **Telangiectatic vessels** → dilated capillaries in the dermis, visible through thin epidermis - **Dermoscopic arborizing vessels** → most specific finding for BCC - **Slow growth over 8 months** → consistent with BCC's indolent course - **Location on face** → sun-exposed area, highest risk site for BCC **Mnemonic:** **PEARL** = **P**early nodule, **E**xcentric ulcer (rodent ulcer), **A**rborizing vessels, **R**olled border, **L**ow metastatic potential. ### Management Implications - Biopsy (punch or shave) for histopathological confirmation - Mohs micrographic surgery for high-risk lesions (periocular, perioral, >2 cm, recurrent) - Surgical excision with 4–5 mm margins for low-risk BCC - Cryotherapy or topical 5-FU for superficial BCC in low-risk areas - Radiotherapy for elderly patients unfit for surgery [cite:Robbins 10e Ch 25]