Cutaneous Leishmaniasis: Clinical features

Various forms are clinically distinguished, the most important of which are :

• Localised cutaneous leishmaniasis: skin ulcers that heal very slowly or nodular lesions, limited in extent and number. These chronic sores have regional names: clou de Biskra in Algeria and Aleppo boil in Syria.

• Diffuse cutaneous leishmaniasis: cutaneous nodules and plaques that do not ulcerate but can sometimes spread over the entire body.

• Recurrent cutaneous leishmaniasis

  
  

A description from 1756 by a certain Alexander Russell is still relevant:

"... After it is cicatrised, it leaves an ugly scar, which remains through life, and for many months has a livid colour. When they are not irritated, they seldom give much pain... It affects the natives when they are children and generally appears in the face, though they also have some on their extremities... In strangers, it commonly appears some months after their arrival. Very few escape having them, but they seldom affect the same person above more than once."

Localised cutaneous leishmaniasis

After a bite by a sandfly infected with L. tropica (mainly urban infection), there is an incubation period of a few weeks or months, occasionally years. There is initially a small papula and usually only a single lesion, though sometimes there are several. This slowly spreads, can remain completely dry, become warty or nodular or develop into a painless, sharply delineated ulcer surrounded by a purplish raised border. Satellite lesions can occur. Spontaneous healing often occurs after 6 to 12 months, resulting in a depressed scar. Recurring cutaneous lesions - possibly with severe disfigurements - occasionally occur. There is usually immunity to any subsequent infection with the same organism. In infection with L. major (mainly rural infections, particularly from a rodent reservoir) the lesions are usually larger and develop more quickly, hence the name. There is a greater tendency to local spreading via the lymphatics and have to be distinguished from sporotrichosis. The lesions will eventually spontaneously heal with scar formation.

In South America the lesions often have their own local names and clinical expressions. Hence in Peru they are called "uta" (a solitary ulcer or a few restricted lesions brought about by L. peruviana, frequently on the face). In Guyana they are known as "bush yaws" or (French) "pian bois" (L. guyanensis) with rasberry-like lesions that resemble yaws. In Yucatan, Mexico an ulcer on the ear (usually caused by L. mexicana) is know as "chiclero" ulcer.

Diffuse cutaneous leishmaniasis

Diffuse cutaneous leishmaniasis is a diffuse affection of the skin with extensive non-ulcerative nodules and is a very chronic disease. It is sometimes followed by chronic lymphoedema of an affected part of the body. This disease is poorly understood, but is probably caused by a diminished resistance to the parasite. This immunosuppression is possibly brought about by the parasite itself. In East Africa diffuse cutaneous leishmaniasis is often caused by L. aethiopica and in the New World frequently by L. mexicana.

If there are generalised cutaneous lesions the condition has to be differentiated from lepromatous leprosy, keloids, neurofibromatosis and post kala azar dermal leishmaniasis (PKDL). Due to the low resistance of the patient very numerous amastigotes are present skin smears are always positive. Treatment is difficult, as the patient’s immune system itself is functioning poorly. Differentiation from PKDL is important, as the latter can still be treated reasonably well. In Sudan 1 case of diffuse cutaneous leishmaniasis is found for every 100 cases of localised cutaneous leishmaniasis. The incidence varies greatly from district to district. It occurs frequently in South America, but in contrast to this it does not occur in India.

Recurring cutaneous leishmaniasis

Recurring cutaneous leishmaniasis seldom occurs (Iraq, Iran). This disease, also known as leishmaniasis recidivans leads to significant tissue damage. Parasites are very difficult to detect in these very chronic lesions. Differentiation from cutaneous tuberculosis is important.

Category: Medicine Notes