Desmoplastic Small Round Cell Tumor of the Kidney Mimicking Wilms Tumor

Abstract

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive, malignant neoplasm usually present with the widespread abdominal serosal involvement and affects mainly adolescents and young adults. When presenting within visceral organs, as kidney, the diagnosis of DSRCT imposes significant difficulties. We present a case of primary DSRCT of the kidney in a 10-year-old boy mimicking clinically and pathologically Wilms tumor. The tumor showed morphologic and immunohistochemical features of DSRCT and the presence of the Ewing sarcoma and Wilm tumor 1 fusion transcripts resulting from the t(11;22) (p13;q12) reciprocal translocation. DSRCT should be considered in the differential diagnosis of Wilm tumor and other small blue-round cell tumors of the kidney.

Immunohistochemistry as potential diagnostic pitfall in the most common solid tumors of children and adolescents

“…Cytoplasmic WT1 staining can also be obtained in up 43% or 63% of cases of EWS/pPNET by using antibodies against C-terminus or N-terminus of WT1 protein, respectively (Nakatsuka et al, 2006). Differential diagnosis may be challenging if we consider that both DSRCT and EWS/pPNET may arise primarily from the kidney (Wang et al, 2007;da Silva et al, 2009;Jimenez et al, 2002). Unlike EWS/pPNET, DSRCT lacks diffuse CD99 staining and co-expresses epithelial markers, desmin and WT1.…”

“…This overlapping immunohistochemical feature may pose serious diagnostic problems, if we consider that some cases of Wilms' tumor are so large in size that it may be difficult establishing, by radiological imaging, their origin from the kidney. In addition there is the possibility that DSRCT may primarily arise in visceral organs, including kidney of children and adolescents, as well as in the retroperitoneum (Wang et al, 2007;da Silva et al, 2009). Based on these clinicopathologic considerations, distinguishing a blastemal-dominant Wilms' tumor from a DSRCT (Arnold et al, 2014;Wang et al, 2007;da Silva et al, 2009) may be challenging (Fig.…”

“…In addition there is the possibility that DSRCT may primarily arise in visceral organs, including kidney of children and adolescents, as well as in the retroperitoneum (Wang et al, 2007;da Silva et al, 2009). Based on these clinicopathologic considerations, distinguishing a blastemal-dominant Wilms' tumor from a DSRCT (Arnold et al, 2014;Wang et al, 2007;da Silva et al, 2009) may be challenging (Fig. 6A), especially if pathologist is facing with a small, round-to ovoid-shaped cell component as the only cytotype seen in small biopsies from renal/intra-abdominal masses .…”

PAX2 Expression in Wilms Tumors and Other Childhood Neoplasms

“…In addition, blastema predominant/monophasic Wilms tumors present a particular diagnostic challenge, 15 as they may be difficult to distinguish from other small round cell tumors, especially on small biopsy, in the setting of metastatic disease, or in an unusual clinical presentation. 5,15,32 Individual case reports have illustrated the difficulty in accurately distinguishing blastema predominant Wilms tumors from other small round cell tumors, especially PNET and desmoplastic small round cell tumor (DSRCT). 5,32 In this setting, ancillary studies such as immunohistochemistry and cytogenetic and molecular analyses have an invaluable role in diagnosis; however, to date, there are no known recurring cytogenetic translocations or immunohistochemical markers characteristic of Wilms tumors.…”

“…5,15,32 Individual case reports have illustrated the difficulty in accurately distinguishing blastema predominant Wilms tumors from other small round cell tumors, especially PNET and desmoplastic small round cell tumor (DSRCT). 5,32 In this setting, ancillary studies such as immunohistochemistry and cytogenetic and molecular analyses have an invaluable role in diagnosis; however, to date, there are no known recurring cytogenetic translocations or immunohistochemical markers characteristic of Wilms tumors. In those situations in which ancillary studies are needed for diagnosis, WT1 has not proven to be a sensitive or specific marker for Wilms tumors.…”