A Case of Renal Inflammatory Pseudotumor Leading to Nephrectomy

Abstract

Inflammatory pseudotumor (IPT) of the kidney is a rare benign disorder with unknown etiology. In IPT patients, some nonspecific symptoms might present, such as fever, hematuria, and back pain. As it can appear on computed tomography and magnetic resonance imaging as a hypovascular mass with surrounding fat stranding, IPT can be misdiagnosed as a primary tumor. Since the clinical symptoms, radiographic features, and preoperative findings can be inconsistent, it is imperative to confirm IPT based on histopathological assessment. In the present study, we describe a case of renal IPT in a 13-year-old girl. The patient was treated with nephrectomy of the right kidney since the preoperative diagnosis was renal carcinoma. Pathological examination revealed an IPT. This article emphasizes the importance of preoperative definitive diagnosis in avoiding unnecessary nephrectomy.

Keywords: inflammatory myofibroblastic tumor; inflammatory pseudotumor; kidney.

Figure 1.

Axial precontrast abdominal computed tomography image revealed that the right kidney was enlarged, homogenous, and slightly low density when compared with the left kidney.

Figure 2.

The mass in the right kidney was heterogeneously low-enhancing with ill-defined margins (A). Some hypodense portions of the mass extended beyond the renal capsule into the perirenal space (B).

Figure 3.

The lesion showed an elevated level of enhancement in the venous phase (A and B). The lesion was in the lower renal pole and extended into the perirenal fat space (C).

Figure 4.

Gross examination revealed a wedge-shaped, well-circumscribed mass with a pale-yellow cut surface occupying most of the lower renal pole and extending into perirenal fat tissue.

Figure 5.

(A) The lesion area showed a loss of renal structure (right) compared with the normal parenchyma (left; hematoxylin-eosin [HE] ×40). (B) Inflammatory infiltration into perirenal fat tissue (HE ×40). (C) Renal tubules were destroyed or filled with cell debris, and several intact glomeruli were observed (HE ×100). (D) Renal parenchyma was replaced by mixed inflammatory infiltration (HE ×400).