Intraoperative Consultation During ENT and Laryngeal Surgery

Ear, nose, and throat (ENT) surgeons perform a variety of surgical procedures that require intraoperative consultation (IOC) with frozen section (FS). Surgical pathologists can receive biopsies or resection specimens from a variety of locations, including the oral cavity, floor of mouth, oropharynx, tonsil, nasopharynx, hypopharynx, larynx, parotid gland and neck lymph nodes. These specimens can exhibit a large variety of neoplastic and nonneoplastic conditions, some unusual, resulting in difficult diagnostic problems during intraoperative consultations.

Tumors in the head and neck area are relatively infrequent and difficult to treat; these surgical procedures are usually performed in tertiary medical centers staffed by surgeons with experience in particular operations. The type of specimen received by pathologists at those institutions varies according to the interests and experience of ENT surgeons in a particular hospital. For example, if the ENT surgeons have an interest in the treatment of laryngeal cancer or in radical resections and reconstruction for the treatment of advanced tumors of the oral cavity, tongue, or other carcinomas, pathologists usually will be asked to diagnose common malignancies such as squamous cell carcinoma and/or evaluate resection margins. If ENT surgeons are interested in the resection of salivary tumors with minimally invasive techniques, or in nasopharyngeal lesions, pathologists will be confronted with the intraoperative diagnosis of a variety of neoplastic and nonneoplastic conditions, some of them unusual. As it is beyond the scope of this chapter to provide a comprehensive review of ENT pathology, we will review our experience with the most common diagnostic intraoperative challenges encountered at the Memorial Sloan Kettering Cancer Center (MSKCC) and Cleveland Clinic Florida (CCF) during head and neck surgery.

Indications of IOC With Frozen Section During ENT Surgery

Intraoperative Diagnosis of Malignancy

In our institutions a variety of biopsies, particularly from laryngeal lesions, are performed to determine whether a lesion can be diagnosed by FS and/or confirm whether diagnostic tissue has been procured. In these biopsies, pathologists can usually diagnose malignancy with accuracy and in most cases identify the tumor lineage as epithelial, mesenchymal, lymphoid, or melanocytic in origin. Biopsies from the larynx are the most frequent FS for diagnosis of ENT lesions in our practice; the most common malignant diagnosis rendered in these specimens is squamous cell carcinoma (SCC). Mucosal melanomas, lingual/tonsillar lymphomas, and neuroendocrine tumors of the larynx also occur but are quite unusual in our busy surgical pathology practice and are probably very unusual in most community hospitals.

Evaluation of Surgical Margins

Another important indication of intraoperative consultations with FS during ENT surgery is the evaluation of surgical margins, which requires recognition of benign versus malignant lesions. This diagnosis often needs to be rendered on the basis of very small samples. In particular, intraoperative evaluation of lingual margins is essential in the evaluation of squamous cell carcinoma of the oral cavity, directly related to local-regional control, and often hampered by cautery artifact. Recognition of the morphologic features that can be generalized across tissue types can help in clarifying these distinctions and rendering a correct diagnosis.

Contraindications to Frozen Section During ENT Surgery

Surgical pathologists must bear in mind that there are contraindications to FS during ENT surgery and that a most important responsibility during IOC is to ensure that tissues are properly preserved and triaged so that a pathologic diagnosis can be rendered either by FS or on permanent sections without the need for additional biopsies or surgeries. ENT specimens are often limited in size because of proximity of tissues to vital structures, functional necessity of the diseased organ, and potential disfigurement secondary to removal. If performing a FS will compromise the final diagnosis because of a very small sample or tumor size, the pathologist should explain to the ENT surgeon that performing the diagnostic procedure will likely render the scanty available tissues undiagnosable and decline to freeze the tissue.

Another general guideline that can be used during the intraoperative handling of specimens is to never freeze the entire area of interest . For example, if a lesion is smaller than 1 cm, the pathologist should sample only one half or even one third of the lesion to ensure that permanent sections from well-fixed tissues can be prepared thereafter. The surgeon cannot always obtain an additional sample, and it is best to have additional well-fixed tissue that has not been used for FS for permanent sections.

Pathologists should also convey to their surgical colleagues that if no surgical action will be taken as a result of the FS diagnosis, the procedure is not indicated and misuses the financial resources of the hospital.

Limitations of Frozen Section

Physical features of a tissue, including the presence of bone or extensive ossification can preclude even an experienced technician from being able to successfully cut a frozen section. Because of charge and van der Waals forces, formalin fixation will inhibit tissue from physically adhering to a frozen section slide. Similarly, fat can be nearly impossible to cut on frozen section. If excessive electrocautery has been used, the thermal artifact will obscure diagnostic histopathologic features. The complexity of a neoplasm , one that requires extensive immunohistochemical (IHC) workup or molecular analysis, may further preclude final diagnosis at the time of frozen section. In such an instance, the most information the pathologist can provide to the surgeon is whether or not the tissue biopsied is lesional tissue, which upon further workup, including formalin fixation and the generation of permanent sections, will be diagnostic.

Sources of Error During IOC with Frozen Section

Inadequate tissue sampling may lead to an erroneous negative result or a nondiagnostic result. For instance, partial freezing of a neck lymph node looking for metastatic disease may miss the diagnostic tissue—the metastasis may only be represented in the portion not sampled. In general, the greater the surface area the pathologist has to evaluate, the lower the likelihood of missing lesions that cannot be seen grossly and the greater caution that should be used during the selection of tissue samples to be frozen. For example, during the evaluation for metastatic disease in lymph nodes larger than 1 cm, the lymph nodes should be bisected and entirely frozen.

Another source of problems during FS are interpretative errors as a result of overlooking focal lesions on a FS slide or misinterpretation of morphologic features because of unfamiliarity with a particular diagnosis or freezing artifacts that distort the histopathology of a lesion.

Communication failures between pathologist and ENT surgeons are potentially avoidable sources of FS errors. They can result because the surgeon failed to adequately transmit relevant patient history or explicitly communicate which information is needed to guide his or her surgical resection. On the diagnostic side of the intraoperative consultation, the pathologist should always ask himself or herself what is the question that the surgeon wants to answer; in instances when this is unclear, the pathologist should never assume that he or she can read the surgeon’s mind and should call or visit the operating room and ask for the proper information. Other errors resulting from communication failures include the reticence of the pathologist to explain that the diagnosis of a particular FS is limited as a result of freezing artifact or other technical problems and plain miscommunications when a FS diagnosis is dictated over the phone to a nurse or another individual other than the ENT surgeon. The latter errors are particularly egregious and can be avoided by routinely asking the person receiving the FS diagnosis to repeat the diagnosis.

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