What is the term for a swollen red area of skin that feels hot and tender?

The term for a swollen red area of skin that feels hot and tender is cellulitis. Cellulitis is a bacterial skin infection that manifests as inflammation, resulting in redness, warmth, swelling, and tenderness in the affected area. The infection can occur when bacteria enter the skin through a cut, scrape, or other breaks in the skin barrier.

In contrast, dermatitis refers to inflammation of the skin that can be caused by various factors, including irritants or allergens, but it doesn't necessarily involve the warmth and tenderness associated with cellulitis. Eczema is a specific form of dermatitis that often includes symptoms like itching and redness, typically more chronic than acute. Lentigenes, on the other hand, are benign lesions or spots on the skin that are generally caused by sun exposure; they do not present as swollen or tender areas. Thus, the characteristics of cellulitis distinctly define it as the correct answer in this context.