Tropical phagedaenic ulcer

**Definition:** Tropical (phagedaenic) ulcer is an acute or chronic skin disease seen in the tropics and subtropics that is characterised by necrosis of the epidermis and underlying superficial tissue. Ulcers may heal spontaneously, leaving regular depressed scars, but sometimes enlarge to enter a chronic phase. Chronic ulcers are often large and irregular in shape and may involve the whole circumference of a limb. Pseudoepitheliomatous changes can develop which may proceed to the development of frank squamous carcinoma. Vincent's organisms (Fusobacterium nucleatum and Borrelia vincentii) are thought to play a pathogenic role.