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Author: Dr Delwyn Dyall-Smith FACD, Dermatologist, Australia, 2010.
Malakoplakia is a rare inflammatory tumour that occurs most frequently in the urinary bladder and less often other internal sites. However, there have been rare reports of skin involvement and even rarer cases affecting the tongue. It is probably an abnormal immune reaction to a localised bacterial infection, most commonly Escherischia coli.
Malakoplakia of the skin has been reported in association with:
Malakoplakia of the tongue is very rare. It has presented in children and throughout adult life to extreme old age. Males appear to be more commonly affected than females. Unlike malakoplakia of the skin, there has been no apparent association with immunosuppression nor involvement of internal organs.
Malakoplakia is probably an abnormal response to bacterial infection, usually E. coli. There have been a number of theories proposed to explain this. A reduction in the messenger chemical, cyclic guanine monophosphate, has been noted within the tissue macrophages (immune cells). These cells fail to kill bacteria, with the formation of von Hansemann cells and the development of an abnormal inflammatory reaction.
Malakoplakia of the skin most commonly affects the perianal and genital area, presenting as asymptomatic, itchy or painful growths (tumours).
The skin lesions may be solitary or multiple, arranged in lines or across folds of skin. They are:
The lesions may ulcerate.
Malakoplakia of the tongue usually causes a feeling of something in the throat affecting swallowing or a lump. Pain may be associated. Symptoms may be present for days, weeks or months. On examination, the single lesion is a yellow, pink or tan coloured soft tumour mass up to 4 cm in diameter, usually located on the base of the tongue.
The diagnostic feature is the presence of von Hansemann cells containing Michaelis-Gutmann bodies. These intracellular bodies stain positively for calcium and iron and, when fully developed, they resemble an owl's eye.
Bacterial culture will determine which organism is involved.
Many tongue and skin lesions are biopsied or excised initially on suspicion of cancer or other unusual forms of inflammation. Wide surgical excision is not usually recommended.
Additional treatment is usually required as recurrence can occur after surgery. Options have included:
Malakoplakia of the skin or tongue in isolation has an excellent prognosis. In some cases, there have been a spontaneous resolution. However, approximately 25% of cases with skin lesions have associated internal organ involvement, which can affect the outcome.
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