August 18, 2017
An adult patient in the mid-fifties with a deceased donor renal transplant for three years (primary disease “hypertensive nephrosclerosis”) presented with a low-grade fever and a rising creatinine. Urinalysis showed hematuria and proteinuria. A transplant biopsy was performed.
1. Low power showing one relatively intact core and a second core showing diffuse replacement of the usual renal parenchyma by inflammation and fibrosis (Trichrome, 40x)
2. Mixed inflammatory cell infiltrate (Jones Silver, 400x)
3. Macrophages with PAS-positive granules (PAS, 400x)
4. Michaelis-Gutmann body (H&E, 400x
5. Michaelis-Gutmann body (H&E, original magnification 600x)
6. Von Kossa Positive Michaelis-Gutmann bodies (von Kossa, 400x)
This disease was first described by Michaelis and Gutmann in 1902 and later named by Von Hansseman. Malakoplakia comes from Greek words malakos (soft) and plakos (plaque). Chronic bacterial infections associated with numerous macrophages with PAS-positive granular cytoplasm and intracellular deposition of iron and calcium (called Michaelis-Gutmann bodies). Calcium in the granules is identified with a von Kossa stain. Iron can be shown with a Prussian blue stain
Immunocompromised patients (HIV, renal transplant recipients) are predisposed to malakoplakia
Malakoplakia is caused by defects in phagocytic or degradative functions of histiocytes in response to gram-negative coliforms (most commonly E. coli or Proteus). Lysosomal degradation of bacteria is decreased. There is alos a failure of cells to release lysosomal enzymes.
Patients usually present with urinary symptoms and urinary tract infection as a result of malakoplakia.
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