DermNet NZ

Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Tropical ulcer

Tropical ulcer is also called tropical phagedaenic (phagedenic) ulcer. This is a painful, rapidly enlarging sore, usually found on the lower limb of an individual living in a hot, humid tropical region. Phagedaenic refers to its appearance as if it was gnawed.

What is the cause of a tropical ulcer?

Multiple factors play a role in causing tropical ulcers.

Clinical features of a tropical ulcer

The ulcer is initially circular, superficial, very painful, and has purple edges. It enlarges rapidly across the skin and down into deeper tissues such as the muscle or even the periosteum (the fibrous membrane covering the surface of bones). The ulcer may reach several centimetres in diameter after a couple of weeks. The edges become thickened and raised and the central crater may become necrotic (blackened due to death of tissue) and foul-smelling.


It is important to rule out other causes of ulcers such as cutaneous leishmaniasis, atypical mycobacteria, pyoderma gangrenosum, and venous disease. Swabs can be taken from the base and edges of the ulcer to determine the type of bacteria present.


Antibiotics such as tetracycline and metronidazole are used. Surgical debridement (removal of dead tissue) and skin grafts may have a role.

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Author: Marie Hartley, Staff writer

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If you have any concerns with your skin or its treatment, see a dermatologist for advice.