The most dangerous form of skin cancer is:

• A. Malignant melanoma
• B. Basal cell carcinoma
• C. Squamous cell carcinoma
• D. Non-melanoma carcinoma

Answer: (A)

Dangers of a skin cancer are largely about its ability to spread beyond the skin. Malignant melanoma has the highest risk of metastasis to lymph nodes and distant organs among common skin cancers, which is what makes it the most dangerous. It can arise from a changing mole or a new pigmented lesion and often presents with asymmetry, irregular borders, color variation, a diameter larger than about 6 mm, or changes over time. Because melanoma can spread early, the prognosis worsens as thickness (how deep the cancer grows) increases, underscoring why early detection is so important. Basal cell carcinoma tends to grow slowly and almost never spreads, so it's usually not deadly though it can cause local tissue damage if not treated. Squamous cell carcinoma can spread in some cases, but its overall risk of metastasis is lower than melanoma. Non-melanoma skin cancer generally refers to basal and squamous cell types. So the most dangerous form is melanoma due to its metastatic potential and impact on survival.