Renal hemangiopericytoma in childhood: noninvasive imaging

Abstract

Hemangiopericytoma (HPC) is an uncommon mesenchymal tumor. Only 106 and 60 cases of HPC of soft tissues were seen in two large institutions over a period of 43 and 57 years, respectively. 1• 2 HPC accounts for 1 to 4 % of all soft tissue sarcomas and may occur in any location in the body at any age; however, they are most common in the fifth and sixth decades.1 -3 HPC of kidney is extremely rare with only 14 cases of renal or perirenal HPC having been reported in the English literature.M 3 To our knowledge, this is the first case of renal HPC in childhood. The sonographic and computed tomographic (CT) appearances of this extremely rare renal neoplasm are described. CASE REPORTA 2 year old boy was hospitalized because of left abdominal mass and gross hematuria. The mass was finn and poorly defined on palpation. Urinalysis showed numerous red blood cells. Cytologic examination revealed no malignant cells in the urine. Sonography showed a complex mass in the left kidney 8 cm in diameter (Fig. 1 ). No thrombus was found in the inferior vena cava. Excretory pyelography revealed an enlarged left kidney with stretched and deformed pyelocalyces. Unenhanced CT showed a left renal mass without calcification, and contrast enhanced scans revealed that the mass was solid with multiple cysts (Fig. 2). Surgery disclosed a well-encapsulated left renal tumor. Perirenal and para-aortic areas were unremarkable. A left nephrectomy was performed. Pathologic examination of the specimen revealed a well-encapsulated renal parenchymal tumor 8 cm in diameter. The cut surface was brownish gray with areas of cyst and necrosis (Fig. 3). The microscopic examination, including reticulin stain of the tumor, revealed renal HPC with questionable malignancy. There was no evidence of recurrence or metastases on follow-up imaging studies 9 months after surgery.

Renal Hemangiopericytoma

“…Calcifications, if present, are speckled and can be seen in 9.6% of abdom inal X-rays and on CT scans in up to 71 % of cases. Ultra sound reveals a complex mass [3].…”