FISH for RET Cyto Block

Test Mnemonic


CPT Codes

  • 88377 - QTY (1)


  • LSI 10q11

Performing Laboratory

Cleveland Clinic Laboratories

Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
4 slidescytologic preparation (slide)SlidesAmbientAmbientCytology cell blocks that have been formalin fixed OR 4 μm formalin fixed paraffin-embedded tissue sections on electrostatically charged slides containing representative tumor, including Pre-H&E. Samples must not be fixed in Prefer or B5.


Environmental Condition Description
RefrigeratedNot preferred
AmbientCell block slides are acceptable

Days Performed

5 days per week

Turnaround Time

5 - 7 days


Name Description
Fluorescent In-Situ Hybridization (FISH) 

Clinical Info

Interphase FISH analysis utilizing a dual color, break-apart probe for the RET gene at 10q11.21. Rearrangements involving RET may be seen in individuals with late-stage, lung adenocarcinomas that are negative for EGFR and ALK rearrangements. The translocation partner gene cannot be identified in this assay. If no cells are available for analysis, no analysis charges will be incurred.

Clinical Limitation

This assay has been validated for cell blocks prepared from cytology samples fixed in PreservCyt solution using the Cellient Automated Cell Block System (Hologic, Marlborough, MA). Blocks prepared with other fixatives and/or methods are not acceptable.