In simple words: A pathologist examines and selects previously diagnosed tissue samples from storage for further molecular testing, such as checking for specific gene changes like the KRAS mutation.

This code describes the examination and selection of previously diagnosed tissue samples stored in an archive for the purpose of molecular analysis, such as KRAS mutational analysis. The pathologist retrieves the archived tissue, examines it, and selects appropriate samples for molecular testing.

Example 1: A patient with a history of colorectal cancer has tissue samples stored from a previous biopsy. To determine eligibility for targeted therapy, the oncologist orders a KRAS mutation analysis. The pathologist uses code 88363 to describe the process of retrieving, examining, and selecting the appropriate tissue sample from the archive for the KRAS testing., A patient with a newly diagnosed melanoma undergoes a biopsy.A portion of the biopsied tissue is archived.Later, to determine prognosis and guide treatment, BRAF mutation analysis is ordered on the archived tissue. The pathologist uses 88363 to cover their work retrieving and selecting the tissue for this analysis., A patient with lung cancer had a resection surgery two years prior. Archived tissue blocks are retrieved to perform EGFR, ALK, ROS1 and PD-L1 testing. Code 88363 is used to report the pathologist's work in selecting the appropriate tissue for these molecular tests.

Documentation should include the original diagnosis, the date the tissue was originally collected, the type of molecular analysis being performed (e.g., KRAS, BRAF), and a clear indication that the tissue used was retrieved from an archive.