What is the primary distinction between cellulitis and erysipelas?

The primary distinction between cellulitis and erysipelas lies in the demarcation of the affected areas. Erysipelas is characterized by well-defined, sharply demarcated borders, which makes it visually distinct from cellulitis. This clear boundary occurs because erysipelas typically involves the upper dermis and superficial lymphatics, leading to a more pronounced inflammatory response.

In contrast, cellulitis involves deeper layers of the skin and subcutaneous tissue, resulting in a more diffuse and less clearly defined area of inflammation. The less pronounced borders in cellulitis can make it harder to identify the extent of the infection at a glance.

Understanding this key difference is crucial for diagnosis and management, as it can influence treatment decisions and expectations for the condition's course.