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Cathepsin K is a protease that is involved in bone resorption, and is highly expressed in osteoclast. Its expression has also been demonstrated in normal skin and lung fibroblasts. In neoplastic tissue, Cathepsin K has been reported to be expressed in most mesenchymal tumors, but only rarely in carcinomas. Cathepsin K is positive in the majority of translocation renal cell carcinomas (seven of the Alpha-TFEB gene fusion translocation), and in all 5 of the most common TFE3-positive renal cell carcinomas bearing the t(X;1)(p11.2;q21) translocation. This assay is intended for the identification of these renal cell carcinomas. Published data suggest that TFE3 expression leads to cathepsin K expression. While less sensitive than TFE3, cathepsin K has also been demonstrated in a subset of renal cell carcinomas showing a different translocation, t(6;11). While these latter translocations cannot be identified with antibodies to TFE3, they may account for the apparent reduced specificity of cathepsin K in our study, as the TFE3-negative, Cathepsin K-positive renal cell carcinomas may well correspond to these t(6;11) translocation renal cell carcinomas. Final determination of translocation status in renal cell carcinomas may require FISH or PCR studies. Subcellular Localization: Cytoplasmic
Organ: Genitourinary Tumors
CPT Code(s): 88342 or 88341. The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.
Turnaround Time: Within 1-2 business days of receipt
Schedule: Monday - Friday
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR - • 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm