Tuberculosis of the genitourinary system-Urinary tract tuberculosis: Renal tuberculosis-Part II

Abstract

This article reviews the computed tomography and magnetic resonance imaging (MRI) features of renal tuberculosis (TB), including TB in transplant recipients and immunocompromised patients. Multi detector computed tomography (MDCT) forms the mainstay of cross-sectional imaging in renal TB. It can easily identify calcification, renal scars, mass lesions, and urothelial thickening. The combination of uneven caliectasis, with urothelial thickening and lack of pelvic dilatation, can also be demonstrated on MDCT. MRI is a sensitive modality for demonstration of features of renal TB, including tissue edema, asymmetric perinephric fat stranding, and thickening of Gerota's fascia, all of which may be clues to focal pyelonephritis of tuberculous origin. Diffusion-weighted MR imaging with apparent diffusion coefficient (ADC) values may help in differentiating hydronephrosis from pyonephrosis. ADC values also have the potential to serve as a sensitive non-invasive biomarker of renal fibrosis. Immunocompromised patients are at increased risk of renal TB. In transplant patients, renal TB, including tuberculous interstitial nephritis, is an important cause of graft dysfunction. Renal TB in patients with HIV more often shows greater parenchymal affection, with poorly formed granulomas and relatively less frequent findings of caseation and stenosis. Atypical mycobacterial infections are also more common in immunocompromised patients.

Genitourinary tuberculosis in North America: A rare clinical entity

“…5 Although these findings may be "typical" of GU TB, the differential diagnoses include partial staghorn stone, calyceal diverticulum with stones, chronic pyelonephritis, cystic renal cell carcinoma with calcification, fungal infections and urothelial carcinoma. Chest imaging may be abnormal in 40% to 75% of patients with genitourinary TB.…”

“…However, the culture takes 6 to 8 weeks to grow and it has a false negative rate as high as 20%. 4,5 Therefore, at least 3 first morning midstream urine samples are advised to isolate the organism. 6,8 In addition, patients need to be off antibiotics at the time of urine collection since antibiotics may inhibit mycobacterial growth in culture.…”

“…A special acid-fast bacterial culture is required, taking up to 8 weeks for Mycobacterium tuberculosis to grow, with a false negative rate as high as 20%. 4,5 Imaging findings are also non-specific and may even further delay diagnosis. 6 The astute clinician must have a high degree of suspicion for genitourinary TB in patients presenting with non-specific symptoms, culture-negative pyuria, and for whom imaging studies seem atypical.…”

Renal tuberculosis

“…Slika 3. Kompjuterizovana tomografija prikazuje granulome u parenhimu (crne strelice), kalijektazije i ureterektazije praćene zadebljanjem urotela (bele strelice) (15) Kompjuterizovana tomografija je najosetljivija metoda za utvrđivanje bubrežnih kalcifikacija (16). Ona prikazuje mnogo detaljnije patološke promene u odnosu na intravensku urografiju i ultrasonografiju, posebno u otkrivanju multiplih sitnih urotelnih lezija.…”

“…Kompjuterizovana tomografija je pogodna za utvrđivanje retroperitonealnog širenja bolesti u perirenalni i pararenalni prostor ili zahvatanja i musculus psoasa. Mogu se utvrditi i zahvaće-nost nadbubrežne žlezde, postojanje retroperitonealnih ili potkožnih kolekcija, retroperitonealne fibroze, a mogu da se ispitaju i prostata, semene kesice i zahvaćenost kičme-nog stuba (5,15).…”