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Urinary Tract Infections (UTI)
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Nish Bedi, Ali Omar, Jas S. Kalsi
Malakoplakia is a rare inflammatory condition which commonly presents as a papule, plaque or ulceration that usually affects the genito-urinary tract. Microscopically it is characterised by the presence of foamy histiocytes with basophilic inclusions called Michaelis-Gutmann bodies and usually involves gram-negative bacteria. Malakoplakia is thought to result from the insufficient killing of bacteria by macrophages and the partially digested bacteria therefore accumulate in macrophages and lead to a deposition of iron and calcium. The impairment of bactericidal activity manifests itself as the formation of an ulcer, plaque or papule. It 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.
Pathology of Human Bladder Cancer and Related Lesions
Published in George T. Bryan, Samuel M. Cohen, The Pathology of Bladder Cancer, 2017
Gilbert H. Friedell, George K. Nagy, Samuel M. Cohen
Malakoplakia (see Figure 20) is a form of chronic cystitis characterized by the presence on the mucosal surface of soft, yellowish plaques or nodules caused by subepithelial infiltration of large numbers of histiocytes, many of which contain laminated, round, or oval cytoplasmic inclusions.95 These latter inclusions are called Michaelis-Gutmann bodies and stain heavily with hematoxylin and contain calcium and iron. Electron microscopy of these inclusions has demonstrated the presence of cellular debris and bacteria, suggesting incomplete intracellular degradation of engulfed material, possibly related to deficient acidification within phagolysosomes. Although malakoplakia is more common in the bladder, it has been reported to involve other organs, including testis, GI tract, and kidney. In early phases, the inflammatory infiltrate is composed predominantly of plasma cells and few if any calcified inclusions are noted. Later on, the histology is more typical as histiocytes become the dominant cells and Michaelis-Gutmann bodies are numerous. Finally, a less-specific sclerosing phase develops with numerous fibroblasts and collagen bundles between the histiocytes.
Rectal malakoplakia
Published in Baylor University Medical Center Proceedings, 2020
Ted George Achufusi, Kegan Jessamy, Philip Chebaya, Sekou Rawlins
Malakoplakia was first described by Michaelis and Gutmann in 1902 after it was observed in the bladder. It was named by Van Hansemann in 1903. The term malakoplakia stems from the Greek malakos (soft) and plakos (plaque) and reflects its usual appearance as a friable, yellow mucosal lesion on endoscopy. Coliform bacteria in macrophage cytoplasm (von Hansemann histiocytes) (Figure 1b,c) and laminated intracytoplasmic inclusion bodies (Michaelis-Gutmann bodies) (Figure 1c) are considered diagnostic features. It is hypothesized that a defect of macrophage phagolysosomal response to bacterial infection is the cause of malakoplakia. Glucocorticoids and azathioprine have been shown to contribute to macrophage abnormality, and their discontinuation has been shown to reverse macrophage abnormalities and clinical symptoms. The presence of a bacterial infection has been described in most reported cases, regardless of the affected organ. The two most commonly isolated organisms include Klebsiella pneumoniae and Escherichia coli, but other organisms including gram-negative, gram-positive, and acid-fast bacilli have also been isolated.1 Fungi, including Paracoccidioides brasiliensis, and viruses have also been implicated in isolated cases.2