A 62-year-old man with fair skin and history of chronic sun exposure presents with a painless, slow-growing nodule on his nose with central ulceration and rolled edges. Histopathology confirms basal cell carcinoma. Which of the following is NOT a characteristic feature of basal cell carcinoma?

## Characteristic Features of Basal Cell Carcinoma ### Correct Features (Options 0, 2, 3) **Key Point:** Basal cell carcinoma (BCC) is the most common malignant skin tumor, but it is characterized by extremely low metastatic potential—metastasis occurs in <0.1% of cases. | Feature | Details | |---------|----------| | **Origin** | Arises from basal layer of epidermis (stratum basale) | | **Histology** | Palisading arrangement of basaloid cells at tumor periphery; retraction artifact creating clefts between tumor and stroma | | **Genetic basis** | PTCH1 (Hedgehog pathway), TP53, CDKN2A mutations; associated with Gorlin syndrome (PTCH1 mutations) | | **Growth pattern** | Slow-growing, locally invasive | | **Metastasis** | Extremely rare (<0.1%); virtually never metastasizes | ### Why Option 1 Is Wrong **High-Yield:** Despite being a malignant tumor, BCC has virtually NO metastatic potential. Metastasis to regional lymph nodes or distant organs is exceptionally rare and clinically insignificant. This is a defining characteristic that distinguishes BCC from squamous cell carcinoma (which metastasizes in 2–5% of cases) and melanoma (which metastasizes frequently). **Clinical Pearl:** The low metastatic rate means BCC, though locally destructive, rarely causes systemic spread. Treatment focuses on local control rather than staging for distant disease. ### Clinical Context The patient's presentation (nodule on nose, central ulceration, rolled edges) describes the classic "rodent ulcer" morphology of nodular BCC—the most common histological subtype.