Applications of Touch Preparation Cytology to Intraoperative Consultations: Lymph Nodes and Extranodal Tissues for Evaluation of Hematolymphoid Disorders
Since touch preparation cytology is widely used in the intraoperative setting for tissues being evaluated for a hematolymphoid malignancy, as discussed in chapter “Intraoperative Consultations of Tissue for Evaluation of Hematolymphoid Disorders or Malignancies: Appropriate Handling, Including Touch Preparation Cytology Versus Frozen Section,” this chapter primarily discusses the applications of this technique in this setting.
Lymphoid tissues: This technique is primarily used for evaluation of “lymphoid tissues” to determine adequacy of the specimen for evaluation of a hematolymphoid process. The presence of granulomata does not exclude a hematolymphoid malignancy and should be handled in such a way that appropriate ancillary testing is performed to exclude a malignant lymphoma. If a non-hematolymphoid malignancy is identified, then the specimen should be routed to surgical pathology. Otherwise, the specimen should be routed to hematopathology for appropriate triaging.
Extranodal tissues: These tissues are handled similarly to “lymphoid” tissues if the patient has a hematolymphoid malignancy or if a hematolymphoid malignancy is highly suspected. If in doubt, it is highly recommended to handle the specimen as a “lymphoid” specimen, so that all appropriate testing is performed for diagnostic and prognostic purposes.
Although touch preparation cytomorphology of these tissues is primarily performed in the intraoperative setting to determine appropriate handling of the specimen, the findings may provide useful diagnostic information in classifying the following various hematolymphoid malignancies: myeloid sarcomas, malignant lymphomas composed predominantly of small lymphocytes, large-cell lymphomas (such as anaplastic large-cell lymphoma), and Burkitt lymphoma. However, the technique inherently has limitations (such as sampling issues, the inability to accurately determine the proportion of large cells and pattern of involvement, etc.) and should be evaluated in conjunction with the permanent histologic sections and ancillary data.