Ecthyma

**Definition:** Ecthyma is a superficial ulcerative bacterial pyoderma. It is characterised by small, purulent, shallow, punched-out ulcers with thick, brown-black crusts and surrounding erythema. The commonest form is caused by beta-haemolytic streptococci, often in association with Staphylococcus aureus. It is associated with poor hygiene and malnutrition. Ecthyma gangrenosum is an uncommon severe variant caused by Pseudomonas aeruginosa.