Which condition is identified by the presence of a warm, erythematous, tender nodule that drains purulent material?

The condition identified by a warm, erythematous, tender nodule that drains purulent material is a skin abscess. A skin abscess typically forms as a localized collection of pus that is caused by an infection, often due to bacteria. The presence of warmth, tenderness, and erythema indicates an inflammatory response, which aligns with the characteristics of a skin abscess. The purulent material signifies the accumulation of white blood cells and bacteria, which is indicative of an infection that leads to the formation of pus.

While boils (furuncles) can also present with similar symptoms, they are specifically caused by the infection of hair follicles and may not be as large or localized as a typical skin abscess. Cellulitis is a diffuse infection of the skin and subcutaneous tissues that causes redness and swelling, but it does not typically form a discrete nodule that drains purulent material like an abscess. An allergic reaction usually does not produce purulent material or a localized nodule but rather manifests as widespread inflammation or hives. Thus, the defining characteristic of a warm, tender nodule that drains pus clearly corresponds to a skin abscess.