Case report and literature review of a rare diagnosis of ossifying renal tumor of infancy

Abstract

One must entertain a broad differential diagnosis for infants presenting with gross hematuria. Initial workup includes urine analysis, serum laboratory values and abdominal ultrasound. We describe an infant presenting with gross hematuria found to have a calcified renal mass upon initial ultrasound and subsequent computed tomography scan. We considered a differential diagnosis of, but not exclusive to, staghorn calculi, nephroblastoma, Wilms' tumour, mesoblastic nephroma and ossifying renal tumour of infancy (ORTI). A nephrectomy was performed, and the pathology report identified the calcified mass as an ORTI.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 1. The 1st Decade:From the Radiologic Pathology Archives

“…At sonography, the mass is strongly echogenic with posterior acoustic shadowing and possibly secondary hydronephrosis (Fig 18). Intratumoral flow may be seen with color Doppler imaging (90,94,95). CT shows variable contrast enhancement, distinguishing the tumor from a calculus (Fig 18) (94).…”

“…Intratumoral flow may be seen with color Doppler imaging (90,94,95). CT shows variable contrast enhancement, distinguishing the tumor from a calculus (Fig 18) (94). The few reports of MR imaging of ossifying renal tumor describe low signal intensity on T2-weighted images due to calcification and possibly to dense cellularity (90).…”

Ossifying Renal Tumor of Infancy: Report of a Case With Positive WT1 Immunohistochemistry and High Mitotic Index and Review of the Literature

“…ORTI is a very rare renal neoplasia, with 23 cases reported in the literature. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] A summary of patient clinical data from published cases is shown in Table 1. Mean age at diagnosis is 6.5 months, ranging from 6 days to 2.5 years.…”

“…The presence of mitoses was reported in 3 of the previous cases, although they were not described as particularly numerous. 6,[8][9] No recurrent or metastatic case has been reported and ORTI is therefore considered benign, with 1 case reported free of disease at more than 23 years of follow-up. 4 Some confusion seems to exist in the literature regarding the nomenclature of the various cellular populations in ORTI.…”

“…Ossifying renal tumor of infancy (ORTI) is a rare benign neoplasm of the kidney in infants, first described by Chatten in 1980 1 with 23 cases reported in the literature. [1][2][3][4][5][6][7][8][9][10][11][12][13] Patients usually present with gross hematuria and a calcified mass protruding into the renal pelvis on imaging. 2 Histologically, it is recognized as an osteoid matrix surrounded by 2 populations of cells: an epithelioid component of osteoblast-like cells and a blastemal-like component of round, oval, or spindle cells.…”