Renal translocation carcinomas
Included in the 2004 WHO reclassification are renal translocation carcinomas, which have recently been identified as a distinct subset of renal carcinoma. These tumors were often classified as clear cell variants since they tend to form papillae lined with clear cells resembling conventional clear cell RCC. Most patients present at a young age (between late childhood and early adulthood) and are symptomatic, presenting with hematuria, flank pain, an abdominal mass, or fever.
These tumors tend to be large, with the histology described above.28 Genetic analysis shows that these tumors are associated with alterations to the Xp11.2 gene. These alterations include both translocation and fusion of the genes coding for the microphthalmia transcription factor subfamily, which includes both transcription factors E3 and EB. The proteins overexpressed by these genetic alterations can be identified on immunohistochemical staining and help in diagnosing Xp11.2 translocation tumors. These tumors are rare but they tend to be aggressive, particularly when they occur in adults, and therefore need to be clearly defined.29
Several new and emerging types of renal tumors are being identified that will most likely become part of the standard classifications of RCC. These include tumors associated with end-stage renal disease and tumors with hybrid histology.30 The clinical significance of these tumors remains to be seen and are beyond the scope of this review.
Our knowledge of renal tumors has expanded greatly since the first consensus conference in Mainz and those in Heidelberg and Rochester and will only continue to expand as more renal tumors are identified and evaluated. With greater knowledge of tumor genetics and immunohistochemistry, we will improve our ability to make prognoses and to target therapy appropriately to those who would benefit most.
Maria Alexandra Ordoñez, MD, (left) is an Assistant Professor of Clinical Urology, Department of Urology, Columbia University Medical Center.
Lara R. Harik, MD, (right) is an Assistant Professor of Clinical Pathology, Department of Pathology and Cell Biology, Columbia University Medical Center and New York Presbyterian Hospital.
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