Malakoplakia Presenting as a Mass in the Transplanted Kidney

Abstract

Malakoplakia is a rare inflammatory condition that can affect many organ systems, including the genitourinary tract. It is associated with impaired immune function. Isolated renal parenchymal involvement has been reported in very few cases. Urinary tract and digestive malakoplakia have been reported in transplant recipients, but the involvement of transplant itself is rare. Variable clinical manifestations and nonspecific radiological appearance make the diagnosis difficult. The differential diagnosis includes infective etiologies and malignancy. We report a case of renal allograft malakoplakia, mimicking as a malignancy on 18F-FDG PET/CT.

FDG-Avid Malakoplakia of the Ureter Mimicking Malignancy

“…[4][5][6][7][8] A few case reports demonstrate that malacoplakia can show intense FDG uptake due to inflammatory cell infiltration, mimicking malignancy. [9][10][11][12][13][14][15] This case indicates that malacoplakia should be included in the differential diagnosis of hypermetabolic lesions in urinary tract, especially in patients with chronic urinary tract infection.…”

“…Malacoplakia of the urinary tract can appear as solitary or multiple, polypoid, vascular, solid masses, or circumferential wall thickening associated with dilatation of the upper urinary tract 4–8 . A few case reports demonstrate that malacoplakia can show intense FDG uptake due to inflammatory cell infiltration, mimicking malignancy 9–15 . This case indicates that malacoplakia should be included in the differential diagnosis of hypermetabolic lesions in urinary tract, especially in patients with chronic urinary tract infection.…”

18F-FDG PET/CT in a Patient With Epididymo-Testicular Malacoplakia

“…1,2 Histologically, malakoplakia is characterized by present of von Hansemann cells and Michaelis-Gutmann bodies. 1,2 Because of its rarity and intense 18 F-FDG uptake, [3][4][5] diagnosing malakoplakia with PET/CT can be challenging, particularly when it occurs at atypical locations, as observed in this case. This case emphasizes that, in addition to some known benign (tuberculosis 6 and sarcoidosis 7 ) or malignant conditions (germ cell tumor, 8 stromal tumor, 9,10 metastasis, [11][12][13] and hematological malignancy involvement [14][15][16][17][18] ), the malakoplakia should be considered as a rare differential diagnosis for epididymo-testicular lesions with intense 18 F-FDG uptake on PET/CT, even in immunocompetent patients.…”

Multiple-Organ Involvement of Malakoplakia Mimicking Malignant Neoplasms on 18F-FDG PET/CT

“…In some rare cases, malakoplakia can also infiltrate into adjacent organs, as shown in this case, mimicking malignant tumors. Malakoplakia always exhibits intense FDG uptake in 18 F-FDG PET/CT, owing to the abundance of activated macrophages with increased cellular glycolysis 7–9 . However, the possibility of a huge hypermetabolic malignant carcinoma developing without lymphatic involvement and distant metastasis is extremely unlikely 10 .…”

“…Malakoplakia always exhibits intense FDG uptake in 18 F-FDG PET/CT, owing to the abundance of activated macrophages with increased cellular glycolysis. [7][8][9] However, the possibility of a huge hypermetabolic malignant carcinoma developing without lymphatic involvement and distant metastasis is extremely unlikely. 10 All of these features help to differentiate malignant and inflammatory diseases in this case.…”