In the context of skin infections, what is the layer affected by cellulitis?

Cellulitis primarily involves the deeper layers of the skin, specifically the dermis and subcutaneous fat. It is an acute bacterial infection that can spread quickly through these layers, leading to symptoms such as redness, swelling, and warmth in the affected area.

The entire dermis is affected because cellulitis typically originates from a break in the skin that allows bacteria to enter. This can lead to inflammation in the dermal layer and extend into the deeper subcutaneous fat. As a result, the infection usually does not remain confined to just the epidermis or solely impact the subcutaneous fat or fascia. Understanding this progression is key to recognizing the symptoms and determining appropriate treatment.

Focusing solely on the epidermis or just the subcutaneous fat would overlook the critical role that the dermis plays in the pathology of cellulitis. Similar to how the dermis and subcutaneous fat are interconnected in structure and function, the infection can evolve to impact the entire area, which is why the entirety of the dermis is considered to be involved.