A 20-year-old patient attended the emergency department with lumbar pain and fever. The patient underwent urine cultures, blood cultures and a tumour marker study (tests that were negative). A computerised axial tomography (CAT) scan detected a tumour mass affecting the upper pole of the right kidney. The tumour was then surgically resected.

The surgical resection specimen consisted of a tumour mass 14 cm in diameter, with infiltration of the upper pole and middle segment of the kidney, and involvement of the sinus and pyelocaliceal system. The presence of tumoural lymphatic vascular invasion was observed in the renal tissue and adjacent fat. Medullary metastasis of the adrenal gland, invasion of the perirenal fat and nodules of the interaortic caval chain.
Using immunohistochemical techniques on paraffin sections with different monoclonal antibodies (Dako), the following staining pattern was found to be compatible with a desmoplastic small round cell tumour: cytokeratins 8, 18 and 19 (+), glial fibrillary acidic acidic protein (-), desmin (+), vimentin (+), synaptophysin (+), chromogranin (-), actin (weakly +), and S-100 (weakly +).

A cytogenetic study of the t(11;22) (p13;q12) translocation involving the EWS1 and WT1 genes was also performed by fluorescence in situ hybridisation (FISH) using the LSI EWSR1 (22q12) Dual Color Break Apart Rearrangement Probe (VYSIS) kit. This consists of a mixture of two probes that completely flank the EWS1 gene locus, the more centromeric probe is labelled with Spectrum-Orange and the more telomeric with Spectrum-Green. As a result of this design, any translocation involving the EWS1 locus results in the separation of the red-green fusion signal into a red and a green signal. The pattern observed in our case corresponds to the normal pattern, with the presence of two red-green fusion signals per tumour cell, thus confirming the absence of translocation in the patient.

The patient was treated with three cycles of CAV, four cycles of Ifosfamide/VP-16, and subsequently CTX, ADR, and VCR. As a result of this treatment no tumour infiltration was detected in the bone marrow. However, a reappearance of the tumour and liver metastasis was subsequently detected by CT scan. After which there was no response to treatment and the patient died two years after the initial diagnosis.