The Frozen Section: Pathology in the Trenches

摘要

This year marks the 100th anniversary of the seminal publication in JAMA of a report on a successful frozen section preparation technique by Louis B. Wilson from the Mayo Clinic.1 Indeed, this was not the first time a frozen section was performed and documented: this had happened in Europe for decades during the 19th century on a more or less sporadic manner.2 It was also not the first time that a frozen section was performed in North America. In 1889, John C. Warren, a surgeon from Massachusetts General Hospital, made reference to examining skin biopsy specimens with the freezing microtome, albeit without detailing the technique. In 1895, James H. Wright, Jr, from McGill Hospital, described a technique for boiling tissues in formalin for a few minutes before freezing them.3 In 1891, the eminent pathologist from Johns Hopkins Hospital, William H. Welch, performed a frozen section examination of a breast lesion removed by Dr William H. Halsted. Unfortunately, by the time the microscopic diagnosis was rendered, the surgeon had made up his mind regarding the nature of the lesion and completed the operation,4 which is not an unheard of experience for pathologists, even in modern times. However, the technical quality of most frozen sections during these early years was clearly suboptimal by modern standards. Surgeons such as J. C. Bloodgood, although supporting the concept of the frozen section examination, admitted, in 1908, to not depending on a frozen section to guide the surgical procedure.5 By the early and mid-1920s, however, a consensus spearheaded by surgeons such as J. C. Bloodgood67 and W. J. Mayo8 was taking shape, accepting that intraoperative frozen section diagnosis was a valuable and necessary adjunct to the conduction of surgical operations. In modern times, even though a number of special and histochemical techniques have been proposed on a frozen section basis,9 most such diagnoses are still rendered on the basis of hematoxylin-eosin–stained tissues.Although the first users of intraoperative frozen section diagnoses were largely surgeons and obstetricians, it soon became obvious that the experience and knowledge of a trained pathologist were necessities in such settings. Nowadays, a close interaction between pathologist and surgeon is required for the successful conduction of many surgical operations, and such interaction takes place on a daily basis in large and small hospitals. This aspect of the practice of pathology constitutes a veritable “in the trenches” scenario in which clear and prompt communication between surgeon and pathologist is a requisite. In this setting, no opportunity exists for extensive collegial consultation or leisurely perusal of the literature. Assets such as keen eye, deep fund of knowledge, and experience are, indeed, most valuable. However, perhaps the most valuable of such assets is a combination of common sense (the least common of senses, according to an unnamed wag), a clear understanding of the value and limitations of the frozen section, and firmness of character so as not to cave in to occasional excessive, sometimes unrealistic, expectations of the surgeon.Frozen section examination has a number of indications, such as identification of tissue type, benign versus malignant nature of the tissue, type of malignancy, determination of surgical margins, positivity of lymph nodes, and presence of malignant implants and/or metastases in other tissues. The common denominator of this list is clear: the results will determine the further conduction of the surgical procedure. Otherwise, the setting of frozen tissue examination represents a tradeoff in terms of tissue preservation, extent of sampling, and ability to orient tissues, among other aspects, that results in a suboptimal end product. Curiosity on the part of the surgeon or the patient and need to know the results as soon as possible are definitely not indications for frozen tissue examination; modern tissue handling techniques al