Malakoplakia or malacoplakia (from Greek Malako "soft" + Plako "plaque") is a rare inflammatory condition which makes its presence known as a papule, plaque or ulceration that usually affects the genitourinary tract. However, it may also be associated with other bodily organs. It was initially described in the early 20th century as soft yellowish plaques found on the mucosa of the urinary bladder. Microscopically it is characterized by the presence of foamy histiocytes with basophilic inclusions called Michaelis–Gutmann bodies.
It usually involves gram negative bacteria.
Malakoplakia is thought to result from the insufficient killing of bacteria by macrophages. Therefore, the partially digested bacteria accumulate in macrophages and leads to a deposition of iron and calcium. The impairment of bactericidal activity manifests itself as the formation of an ulcer, plaque or papule.
Malakoplakia is associated with patients with a history of immunosuppression due to lymphoma, diabetes mellitus, renal transplantation, or because of long-term therapy with systemic corticosteroids.
Today, antibiotics are used for treatment of malakoplakia.