What is ecthyma? Ecthyma, like impetigo, is caused by streptococci and/or staphylococci. The upper dermis and epidermis are both affected. Which population is at risk? Ecthyma is common in tropical countries and may develop from impetigo. Those who are undernourished or those working in damp and swampy condition, eg rice paddies, involving wading in water. Ecthyma can follow other infections such as varicella ( chickenpox ) in the tropics ). What are the clinical symptoms? Lesions may develop following trauma to the skin, such as an insect bite or during an episode of impetigo. These often start as a vesicle or pustule with a halo which develops into a blister before breaking down to form a ‘punched out’ ulcer. This is covered with a dark brown bloody crust, which on removal reveals a purulent ulcer surrounded by erythema. Lesions may be solitary or numerous and are generally 2cm or more in diameter. They tend to develop quickly and then become stationary. Slow healing is followed by scarring. The most common locations are backs of legs, thighs and buttocks and occasionally on the trunk and arms. How is diagnosis confirmed? Skin swab for bacteriology. What might it be confused with? Tropical ulcer, however these are usually larger and usually occur singly. Leishmaniasis and anthrax. What preventive measures should be taken? Advice should be given to patients to avoid scratching pruritic lesions such as mosquito bites, chickenpox and scabies. A soothing application such as calamine may be helpful. Avoiding insects through use of nets and repellent sprays. Which treatments are most effective? For limited lesions topical antibiotics (e.g. fusidic acid) or gentian violet applied twice daily may be sufficient. Otherwise a 3 week course of oral antibiotics (flucloxacillin or penicillin), should be given. How should the treatments be used? The crusts can be removed using compresses of gauze soaked in clean warm water or antiseptic solution. Antibiotic ointment or gentian violet should then be gently applied to the base of the ulcer and a clean dressing applied. The topical preparations should be applied twice daily, the dressing should be changed daily. What are the common concurrent problems? Pain. What are the uncommon concurrent problems? Lymphadenitis is sometimes a problem. Occasionally acute streptococcal glomerulonephritis may develop.