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Final diagnosis:

Cutaneous Malakoplakia

Malakoplakia is a rare, benign inflammatory disease first described in 1902 by Leonor Michaelis and Carol Gutmann, followed by von Hansemann in 1903. The term “malakoplakia” stems from the Greek language, (malacos meaning soft, and placos meaning plaque) and appropriately describes the morphological appearance of the disorder. The pathognomonic histological findings are named for the founders: von Hansemann cells (histiocytes with granular, acidophilic, PAS-positive cytoplasm) and Michaelis-Gutmann (MG) bodies (basophilic, PAS diastase-resistant, targetoid cytoplasmic or extracellular inclusions). The typical clinical presentation involves an immunosuppressed patient with friable, soft plaques found on the mucosa of the urinary bladder, often mistaken for malignancy. There is a concordant gram negative bacterial infection, most commonly Escherichia coli (80% of cases), although other organisms including Klebsiella, Staphlococcus aureus, and acid fast bacilli have been described.

Malakoplakia is thought to result from a deficient host response of macrophages to common bacterial infections. Cyclic guanosine monophosphate (cGMP), an important component of phagolysosomal membrane fusion, is essential for intracellular destruction of bacteria. Low levels of cGMP have been described in patients with malakoplakia, resulting in accumulation of incompletely digested bacteria within the phagolysosome. In addition to bacterial debris, organic and inorganic materials including calcium, phosphate, and iron salts accumulate, resulting in the formation of MG bodies. Histologically, von Hansemann cells and MG bodies can be identified, admixed in a background of abundant lymphocytes, plasma cells, and neutrophils. Periodic acid-Schiff (PAS), CD68, lysozyme, and alpha-chymotrypsin stain von Hansemann cells, while MG bodies stain positive with von Kossa and Prussian blue stains.

The genitourinary system is the most commonly involved site followed by the gastrointestinal tract. Cutaneous malakoplakia occurs more rarely, with fewer than 50 cases reported in the literature. Malakoplakia typically affects adults, with an average age of 50; although pediatric and geriatric cases have been reported. Presenting symptoms are non-specific and vary greatly depending on the site and extent of disease. Immunosuppression appears to be a risk factor, and those patients diagnosed with Malakoplakia without any significant medical history may benefit from further investigation for an unknown underlying disorder. Histology is the most reliable diagnostic method. Surgical removal in combination with antibiotic therapy is typically curative and prevents recurrence. Those patients on immunosuppressive agents benefit from temporary tapering or discontinuation of such therapy.

List of References

1. Cięszczyk, K., Puderecki, M., Wronecki, L., Burdan, F., & Szumiło, J. Malakoplakia of the urinary system. Oddział PAN w Krakowie Uniwersytet Jagielloński – Collegium Medicum (2019).

2. Dong, H., Dawes, S., Philip, J., Chaudhri, S., & Subramonian, K. (2014). Malakoplakia of the Urogenital Tract. Urology case reports, 3(1), 6–8.

3. Kohl, S., MD, & Hans, C. (2008). Cutaneous Malakoplakia. Cutaneous Malakoplakia, 132(1), 113-117.

4. Gliddon, T., & Proudmore, K. Cutaneous Malakoplakia. New England Journal of Medicine (2019), 380(6), (580–580).

5. Goldblum, J. , R., Weiss, S. , W., & Folpe, A. , L. Enzinger and Weiss’s Soft Tissue Tumors. Elsevier Health Sciences (2019). Benign Fibrohistiocytic Tumors, (408-410).

6. Mitchell, A., & Dugas, A. Malakoplakia of the colon following renal transplantation in a 73 year old woman: report of a case presenting as intestinal perforation. Diagnostic Pathology (2019), 14(1).

7. Oates PJ, Touster O. In vitro fusion of Acanthamoeba phagolysosomes. III. Evidence that cyclic nucleotides and vacuole subpopulations respectively control the rate and the extent of vacuole fusion in Acanthamoeba homogenates. J Cell Biol. 1980; 85, (804–810).

8. Samian C, Ghaffar S, Nandapalan V, and Santosh S. Malakoplakia of the parotid gland: a case report and review of localised malakoplakia of the head and neck. The Annals of The Royal College of Surgeons of England (2019) 101:5, (309-312).

9. Shane K. Kohl, Christine P. Hans; Cutaneous Malakoplakia. Arch Pathol Lab Med 1 January 2008; 132 (1), (113–117). doi:[113:CM]2.0.CO;2

10. S. Medlicott, C. Magi-Galluzzi, R. Jimenez, K. Trpkov. Malakoplakia Associated with Prostatic Adenocarcinoma. Annals of Diagnostic Pathology (2016), 22 (33-37).

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