Translocations involving the chromosomal region Xp11.2 are frequently detected in renal cell carcinomas (RCCs) which usually affect children and adolescents. The Xp11.2 translocation RCCs represent a predominant and aggressive subtype in the pediatric age group but can also occur in adults. Macroscopically, Xp11.2 translocation RCCs may mimic conventional clear cell RCCs and thus, differential diagnosis of Xp11.2 translocation RCCs is clinically important. Additionally, the unbalanced chromosomal translocation of der(17)t(X;17) (p11.23;q25) is cytogenetically characteristic for alveolar soft part sarcoma (ASPS). ASPS is a rare high grade mesenchymal malignancy affecting mainly adolescents. This translocation fuses the TFE3 gene at Xp11.23 to the ASPSCR1 (alveolar soft part sarcoma chromosome region, candidate 1, a.k.a ASPL) gene on 17q25.3. Diagnosis of ASPS is often difficult due to histologic overlap with other tumors, particularly in small biopsies. Thus, FISH analysis can improve accuracy of ASPS diagnosis.