What type of skin cancer is characterized by exophytic nodules with scaling or ulceration and is the second most common?

Squamous cell carcinoma (SCC) is characterized by exophytic nodules that may exhibit scaling or ulceration. This type of skin cancer arises from the keratinocytes in the epidermis and is known for its potential to invade locally and metastasize, although primary lesions are often treatable when caught early.

The presentation of exophytic nodules is typical for SCC, especially in sun-exposed areas of the skin such as the face, ears, and hands. These lesions can vary in appearance but often have a rough, scaly surface and can progress to ulceration if not addressed. As the second most common skin cancer, following basal cell carcinoma, squamous cell carcinoma represents a significant public health concern, particularly among populations with high UV exposure or immunocompromised individuals.

Understanding these characteristics helps in distinguishing SCC from other skin cancers, which have different clinical presentations and behaviors. For instance, basal cell carcinoma typically presents as pearly nodules or ulcerated lesions without the same level of exophytic growth. Melanoma, on the other hand, usually presents as atypical pigmented lesions, and Merkel cell carcinoma is a rare and aggressive form that often appears as painless nodules rather than exophytic lesions.