An expanding cannula of an excision device and methods for operating the same are disclosed. An expanding cannula includes a body having first and second ends, the first end coupled to the excision device. The expanding cannula further comprises an expanding coring mechanism coupled to the second end of the body, the mechanism including an annular spring, a plurality of formed fingers extending between the annular spring and the second end of the body, and a retractable flexible blade extending from the second end of the body and over the annular spring. A method for excising tissue using an expanding cannula comprises introducing a bladed stylet coupled to the excision device into a target tissue, retracting the bladed stylet to expose a distal end of an expanding cannula, rotating the expanding cannula using a motor drive to advance the expanding cannula into the target tissue, and collecting a tissue sample.
