How is nummular dermatitis described?

Nummular dermatitis is characterized by the presence of coin-shaped plaques that appear on an erythematous (red) base. This distinctive morphology is a hallmark of the condition and helps differentiate it from other forms of dermatitis. The plaques typically have well-defined edges and can be itchy, which can sometimes lead to secondary changes as a result of scratching. The coin-shaped lesions might vary in size but are generally rounded, resembling coins, which is where the name "nummular" is derived from.

The other options describe conditions or features that are not typical for nummular dermatitis. For example, golden crusts would be more indicative of a condition such as impetigo, while small vesicular lesions are often associated with conditions like herpes simplex or contact dermatitis. Yellowish thickened skin on the palms is more characteristic of conditions like palmar psoriasis or eczema, rather than nummular dermatitis. Understanding these specific characteristics is crucial for accurate diagnosis and treatment.