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

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

Ossifying renal tumor of infancy (ORTI) is a rare, benign pediatric tumor of the kidney. Since first reported by Chatten in 1980, 23 cases have been published. Previous authors have argued that ORTI might originate from nephrogenic rests, thereby sharing a pathogenic relationship with Wilms' tumor (WT). ORTI is characterized histologically by a population of polygonal osteoblast-like cells around an osteoid core and densely cellular component of blastemal-like or spindle cells. While the immunohistochemical profile of the cellular components has been reported, to the best of our knowledge, the status of WT1 expression has only been reported once, where it showed negative marking. Mitoses have been described only sporadically in this neoplasm. We report on a case of ORTI with positive WT1 immunohistochemical marking and numerous mitoses. This case highlights a possible pitfall for misdiagnosing ORTI as a WT and provides additional insight into its pathogenesis.

Renal myolipoosteoma: A distinctive lesion in a child

We describe a distinctive renal tumor, a myolipoosteoma (MLO), in an 11-year-old boy who presented with a 6-month history of slight right flank intermittent pain. A gross examination revealed a well-defined, 5.5 cm mass with bone-like consistency. The lesion histologically featured an admixture of mature adipose tissue, spindle cells, and bony components. No atypia, mitotic activity, or pleomorphisms were observed in the tumor. The spindle cells were smooth muscle actin (SMA) and desmin positive but HMB45 and Melan-A negative, indicating that they were of a muscular nature and differed from that of angiomyolipoma (AML). The patient had no evidence of recurrence or metastasis 56 months postoperatively. We speculate that the present tumor, which to the best of our knowledge differs from all previously described tumors, is of nephrogenic rest (NR) origin and has a favorable prognosis.

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

Wilms tumor is the second most common pediatric solid tumor and by far the most common renal tumor of infants and young children. As most tumors are large at presentation and are treated with nephrectomy, the role of imaging is primarily in preoperative planning and evaluation for metastatic disease. However, with treatment protocols increasingly involving use of preoperative (neoadjuvant) chemotherapy (the standard in Europe) and consideration of nephron-sparing surgery, the role of imaging is evolving to include providing initial disease staging information and a presumptive diagnosis to guide therapy. Differential diagnostic considerations include lesions that are clinically benign and others that require more intensive therapy than is used to treat Wilms tumor. In part 1 of this article, the unique histologic spectrum of renal neoplasms of infants and young children is reviewed with emphasis on radiologic-pathologic correlation. Part 2 will focus on renal tumors of older children and adolescents.