Renal malakoplakia mimicking a locally advanced renal mass: A case report.

Malakoplakia is a rare inflammatory condition that can affect many organ systems, including genitourinary tract, it is associated with impaired immune function. It is characterized by distinctive Michaelis-Gutmann bodies. Very rare cases have been reported to present as a locally advanced renal mass.

Introduction

Malakoplakia is an infrequent chronic inflammatory disease, the most involved organ is the bladder, the pseudotumoral form presentation is rare, and particularly a renal mass can resemble renal cell carcinoma. The differential diagnosis with other renal masses is very important, because therapy and prognosis are different.

We present a clinical case of renal malakoplakia in an 87 old man mimicking a malignant locally advanced renal carcinoma.

Case presentation

An 87-year-old man, with history of cholecystectomy, presented with a 3 month history of right flank and upper quadrant abdominal pain, with no fever or gross hematuria. Physical examination revealed mild right flank tenderness with a palpable mass. Abdominal CT scan showed a heterogeneous solid right renal mass, with irregular enhancement, that infiltrated the right posterior lateral abdominal wall (Fig. 1, Fig. 2).

Fig. 1

Contrast-enhanced transverse CT image shows heterogenous mass involving the perirenal and right pararenal spaces.

Fig. 2

Sagital CT scan shows mass infiltrating lateral abdominal wall.

Thus with the preliminary diagnosis of a locally advanced renal malignancy, the patient underwent right retroperitoneal exploration with radical nephrectomy. Histological examination of the kidney and retroperitoneal soft tissue revealed marked chronic granulomatous inflammation, there were also epithelioid histiocytes with granular eosinophilic cytoplasm contained round intracytoplasmic inclusions Periodic Acid Schiff-positive (Michaelis-Gutmann bodies) (Fig. 3).

Fig. 3

Histological examination of the kidney (hematoxylin and eosin stain stain, x 400) showing intracytoplasmic Michaelis-Gutmann bodies within the histiocytic infiltrate.

These findings were consistent with a diagnosis of renal malakoplakia. The patient died from a massive pulmonary embolism.

Discussion

Malakoplakia is an inflammatory condition associated with immunosuppression, infection and systemic illness. It commonly presents with fever, flank pain and palpable mass, and often resembles other renal pathologies. It is necessary to distinguish renal malakoplakia from renal tumors or other processes, including renal cell carcinoma, xanthogranulomatous pyelophritis, renal tuberculosis and renal fungus infection, since work up and treatment of these entities differ. The diagnosis of malakoplakia can prove difficult due to its somewhat non specific findings. It should be suspected if a kidney is enlarged in the presence of a urinary tract infection, it may require renal biopsy. The treatment of malakoplakia depends on the extent of the disease and underlying conditions of the patient. Patients with bilateral or multifocal diseases are most often treated with antibiotics, such as quinolones. In addition, a cholinergic agonist, such as bethanechol chloride, is used in combination, with antibiotics to correct lysosomal defects. Surgical excision is the choice treatment of unifocal disease, but nephrectomy is indicated when the disease into the upper, mid and lower poles of the kidney.

In conclusion, renal malakoplakia must be included in the differential diagnosis, particularly with renal cell carcinoma in patients with fever, flank pain, and a renal mass. The large rapidly growing nodules of malakoplakia may mimic renal cell carcinoma, in these cases fine needle aspiration, a true cut needle or an open biopsy may help the correct diagnosis of a treatable disease and prevent unnecessary surgery.