The purpose of the intraoperative consultation is to provide the surgeon with immediate information concerning the nature of the lesion, to assess the adequacy of the sample, or to evaluate margins. Although traditional belief is that the conventional frozen section is the best technique to address the above questions, intraoperative cytology has emerged as an accurate, simple, and rapid diagnostic tool. Moreover, with the introduction of laparoscopic surgery and stereotactic biopsies, the pathologist is faced with increasingly smaller samples. In such cases, cytology provides an alternative way to obtain high-quality preparations, preserves the tissue for permanent sections, and prevents freezing artifacts that may render the permanent sections suboptimal for a definite diagnosis.
The articles in this issue of Pathology Case Reviews include discussions on the values and limitations of cytology as an intraoperative diagnostic tool. The selected topics cover a spectrum of neoplastic and nonneoplastic lesions in various organs, and present cytology as a complementary or alternative tool to frozen sections in some settings, while stressing the need for frozen sections in others. The following are a few tips that the reader may find valuable during intraoperative consultations:
- When in doubt about the adequacy of the sample, ask for more tissue samples.
- When the gross and cytologic diagnoses are discordant, a frozen section is needed.
- Although smears of tiny samples may yield diagnostic material, the remaining tissue processed for permanent sections may not. Requesting additional tissue samples for permanent sections may be prudent.
- When preparing smears, avoid mixing lesional with non-lesional tissue. Using the tip of the blade is ideal for obtaining a pure sample from a small lesion. In addition, when areas look different by gross examination, make separate smears from each.
The articles in this issue objectively evaluate the role of cytologic preparations in various organs. Dr. Nochomovitz covers the techniques, advantages, and limitations of intraoperative cytology. Dr. Tabbara discusses the different methods of handling sentinel lymph nodes, during surgery, and compares the sensitivity and accuracy of the different approaches. Drs. Kardon and Edelman address the controversial issue of fine needle aspiration versus intraoperative consultation in evaluating thyroid nodules. Dr. Schwartz eloquently presents a case where the intraoperative diagnosis was deferred despite the use of both cytologic preparations and frozen sections. He uses his case to demonstrate that even when the pathologist is unable to reach a definite diagnosis, excluding certain possibilities may pro-vides useful information to guide the hand of the surgeon. Drs. Jones and Ammerman present a case of cerebellar hemangioblastoma and stress the importance of integrating the clinical, radiographic and morphologic findings during intraoperative consultations. They also illustrate that even though hematoxylin and eosin is usually considered the stain of choice in evaluating central nervous system lesions, in some instances, the diagnostic features are best demonstrated in air-dried, Diff-Quik-stained smears (Dade/Travenol Laboratories, Inc., Miami, FL). Drs. Pitman and Lauwers use a case of well-differentiated hepatocellular carcinoma as a vehicle to concisely and clearly discuss the differential diagnosis of hepatic mass lesions, and emphasize the role of preoperative and intraoperative cytology as an important adjunctive diagnostic tool to frozen section. Dr. Centeno discusses the utility and limitations of intraoperative fine needle aspiration in the evaluation of pancreatic masses. Dr. Sasano et al discuss the role of cytologic preparations during parathyroid exploration. Dr. Hegde et al present a case of amyloidosis of the breast to demonstrate that in certain settings a frozen section is required, particularly when there is a discrepancy between the gross impression and cytologic diagnosis.
The proper handling of tissue samples during intraoperative consultation varies according to the setting; however, pathologists will benefit from familiarizing themselves with both the advantages and the pitfalls of intraoperative cytology. Well-prepared cytologic preparations may eliminate the need for a frozen section or at least influence its interpretation. For instance, the diagnosis of mycobacterial infection in the patients with the acquired immunodeficiency syndrome can be rapidly and reliably established on the basis of an air-dried, Diff-Quik-stained smear that clearly demonstrates the characteristic negative image of the organisms in the background and within the cytoplasm of the histiocytes. However, it is also important to recognize that the extent to which this technique is to be relied upon is dependent on the experience and comfort level of the pathologist.
I sincerely thank all the contributors for their collaboration. We hope that the readers find the presented topics informative and useful in their daily practice and that this issue inspires the practicing pathologists and trainees to explore and discover for themselves what the authors have known and come to appreciate for many years.