This invention provides an inventive tissue sampling probe which offers many advantages over probes available in the prior art. Unexpectedly superior results are obtained in connection with the retrieval of intact tissue specimens, because of a unique combination of cutting features, including, in particular, the employment of an electrosurgical cutting element which is extendible to permit ready severance of the distal end of the tissue specimen, without impact to surrounding tissue. Additionally, the inventive instrument is advantageously designed so that portions of the instrument which contact the patient's tissue or fluid discharge (i.e. blood) during a procedure are modular and disposable, to permit ready replacement of those portions with a new module for an ensuing procedure, without the necessity of cleaning and sterilizing the instrument. The versatility of the invention permits its use in many applications, including, for example, breast biopsies, intraoperative staging, laparoscopic surgery, and lymphadenectomy procedures.