Microscopic description:

The bladder mass consisted of basophilic structures known as Michaelis-Gutmann bodies (calcified lysosomes) within clusters of macrophages on histological examination

The cells stained positive for Von Kossa stain, and macrophages stained positive for CD68

Large foamy macrophages with granular cytoplasm

Occasional multinucleated giant cells

Lymphocytes

Based on the histopathological features and IHC stains, the tumor shows features consistent with malakoplakia

Discussion:

Malakoplakia is a very rare chronic inflammatory disease that has been reported more frequently in immunocompromised patients. It can be found in any organ system, though it is seen more often in the urogenital tract, specifically in females.

Bacterial infections, including E. Coli (80% of cases) are thought to be part of the pathogenesis, as research suggests defective bacterial phagocytosis and lysosome function is the cause of the disease.

Usually presents as soft, yellow mucosal plaque or raised, grey lesions of various sizes, depending on location.

Difficult to diagnose due to variable clinical manifestations, as well as radiologic findings that often mimic different diseases and cancers.

Histologically, Malakoplakia can be differentiated by von Hansemann histiocytes with granular, acidophilic, periodic acid-Schiff-positive cytoplasm, and more specifically the presence basophilic, periodic acid-Schiff, diastase-resistant inclusions called Michaelis-Guttman bodies contained within the histiocytes.

  • Useful histochemical methods include von Kossa stain that visualize the calcium or iron deposits in the Michaelis-Guttman bodies, and von Hansemann cells give positive reactions in CD68.

Conservative treatment via medication and antibiotics has been effective, and emphasizes the importance in proper diagnosis, as the conditions it mimics often require surgery and resection. However, in renal malakoplakia, surgical excision may be indicated based on the extent of kidney damage

References:

Purnell SD, Davis B, Burch-Smith R, Coleman P. Renal malakoplakia mimicking a malignant renal carcinoma: a patient case with literature review. BMJ Case Rep. 2015 Jul 15;2015:bcr2014208652. doi: 10.1136/bcr-2014-208652. PMID: 26177998; PMCID: PMC4513562.

Dong H, Dawes S, Philip J, Chaudhri S, Subramonian K. Malakoplakia of the Urogenital Tract. Urol Case Rep. 2014 Nov 18;3(1):6-8. doi: 10.1016/j.eucr.2014.10.002. PMID: 26793484; PMCID: PMC4714269.

Cięszczyk K, Puderecki M, Wronecki L, Burdan F, Szumiło J. Malakoplakia of the urinary system. Folia Med Cracov. 2019;59(2):67-74. PMID: 31659350.

Richter LA, Isaacson M, Verghese M, Krishnan J. Bilateral renal malakoplakia with acute renal failure: a case report and literature review. Can J Urol. 2011 Oct;18(5):5911-3. PMID: 22018155.

CASE IMAGES