Renal Tuberculosis Mimicking Renal Cell Carcinoma

A Case Report

Kays Chaker; Marouene Chakroun; Maroua Gharbi; Mohamed Chebil

Disclosures

J Med Case Reports. 2019;13(139) 

In This Article

Discussion

Urogenital tuberculosis is diagnosed in 1.1–1.5% of all tuberculosis cases and in 5–6% of cases of extrapulmonary tuberculosis.[2] This infection is usually a consequence of local reactivation following hematogenous dissemination of Mycobacterium tuberculosis to the renal cortex during primary pulmonary infection. The renal cortex is also frequently involved with miliary tuberculosis when multiple granulomas are present. The high oxygen tension of the renal cortex is favorable for renal localization.[3] The clinical presentation of urogenital tuberculosis consists of mostly nonspecific symptoms such as frequent urination, pyuria, dysuria, flank pain, fever, and weight loss.[4] Renal seeding following hematogenous spread from the primary site of infection is followed by formation of small inactive granulomas, which give rise to active tuberculosis after a long latent period, and therefore patients usually present in the second to fourth decades of their lives.[4] Intravenous pyelogram was traditionally the standard imaging approach, but computed tomography (CT) is now preferred.[3] The characteristic early finding is erosions of the renal calyx; the erosions subsequently progress to papillary necrosis, hydronephrosis, renal parenchymal cavitation, and dilated calyces. A thickened ureteric wall and structures characterize ureteric tuberculosis. Lesions are most common in the distal third of the ureter. Bladder tuberculosis may manifest as reduced bladder volume with wall thickening, ulceration, and filling defects resulting from granulomatous involvement. CT findings include focal caliectasis, hydronephrosis, calcifications, cortical thinning, and soft tissue masses.[1] Usually, an enhancing renal mass is caused by renal cell carcinoma, metastasis, lymphoma, or an abscess.[1,5] Urogenital tuberculosis rarely manifests as pseudotumors, which otherwise are usually due to hypertrophied column of Bertin, renal dysmorphism, or an unusually shaped kidney.[1,6] In rare cases, urogenital tuberculosis manifests as either single or multiple parenchymal nodules without urinary tract involvement. Patients with this form, known as the pseudotumoral type, present with variably sized but well-defined parenchymal nodules on cross-sectional images.[1] The lesion may simulate a renal hydatid cyst or a pseudotumoral xanthogranulomatous pyelonephritis. In extremely rare cases, however, genitourinary tuberculosis may present as well-defined parenchymal nodules of variable size, with sparing of the collecting system in what is known as pseudotumoral type. With the clinical and radiological findings suggestive of renal cell carcinoma, the patient consequently undergoes surgical removal of the involved kidney, whose histopathological examination unexpectedly establishes the diagnosis of tuberculosis.[3] The diagnosis is confirmed by growth of Mycobacterium tuberculosis in urine or tissue culture. The treatment of urogenital tuberculosis is similar to that of extrapulmonary tuberculosis at other sites. The initial regimen consists of four drugs (isoniazid, rifampin, pyrazinamide, and ethambutol) for 2 months, followed by two drugs (isoniazid, rifampin) for 4 months if the isolate is susceptible to first-line therapy.

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