General Principles of Cytopathology

General Principles of Cytopathology

Brian Collins

  • I. INTRODUCTION. Cytopathology has developed into a discipline that examines cellular elements from throughout the body collected by a wide variety of methods and procedures. It shares with other anatomic pathology disciplines a morphologic study of cells utilizing patterns and cellular features to identify specific pathologic conditions. Cytopathology provides diagnostic information in a wide variety of clinical settings, and can thus be used to guide patient management both at the time of initial diagnosis and during the course of treatment. In broad terms, there are three main areas of cytopathology, specifically (i) gynecologic/Pap slides, (ii) nongynecologic (Non-Gyn), and (iii) fine needle aspiration (FNA).

    The utility of cytopathology is underscored by the fact that virtually all ancillary laboratory techniques used in surgical pathology can also be performed on cytology specimens.

    • A. Immunocytochemistry. Special stains are commonly applied to cytologic samples, often to confirm the morphologic diagnosis, to help in determining the possible primary sites of a tumor, or to determine the presence of specific prognostic markers. In general, cell block sections are preferred for immunocytochemical staining because most laboratories have experience in processing the formalinfixed, paraffin-embedded (FFPE) tissue sections that are generated from cell blocks.

    • B. Flow cytometry. In the presence of a lymphocyte-rich sample, the possibility of a lymphoproliferative process may need to be addressed by flow cytometry. Body fluids, particularly effusions, are amenable to this type of analysis.

    • C. Molecular genetic methods. Cytological preparations, including fluid specimens, brushings, washings, and scrapings, are suitable substrates for molecular analysis. Regardless of the method used to process samples (e.g., whether air dried, ethanol fixed, or used to produce a cell block) it is possible to extract nucleic acids that can be analyzed by a wide variety of genetic assays, including polymerase chain reaction (PCR), DNA sequence analysis, gene expression analysis, and fluorescence in situ hybridization (FISH).

  • II. GYNECOLOGIC/PAP SLIDES. The “Pap test” is the most successful cancer screening test in medicine. After the wide introduction of the Pap smear, the incidence of cervical carcinoma dropped significantly and it remains the mainstay of screening women for cervical carcinoma. Standardized terminology and categorizations for the Pap smear have been developed (The Bethesda System for Reporting Cervical Cytology. New York, Springer-Verlag, Inc.; 2004). The Bethesda Reporting System for Cervical Smears is covered in more detail in the cytopathology section of Chapter 34.

  • III. NONGYNECOLOGIC CYTOPATHOLOGY encompasses a wide variety of body sites, organs, and types of specimens. In general, any lesion that can be drained, brushed, washed, or scraped can be a “non-gyn” cytopathology specimen.

Oct 20, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on General Principles of Cytopathology

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