Modern Techniques in Cytopathology. Группа авторов

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СКАЧАТЬ Cytopathology Milestone Project (PC2) cited this skill as a level 4 milestone in cytopathology training. According to this milestone the cytology trainee should have the following competency: “Describes and discusses indications and/or performs ultrasound-guided FNAB and core-needle biopsy” [1].

      The scope of practice for clinical cytologists is markedly expanded when USFNA is added to their repertoire. In addition to palpable masses, cytologists have the opportunity to sample non-palpable superficial targets. Sampling of palpable masses is also improved. The cytologist has control over needle gauge, number of passes, area of lesion sampled, and, based on rapid on-site cytologic evaluation (ROSE), specimens can be appropriately triaged for ancillary studies such as cell block, immunocytochemical stains, cultures, flow cytometry, molecular studies, and/or core-needle biopsy. With experience, the cytologist can learn how to correlate ultrasound (US) features of a mass with the cytologic findings and can integrate this information into the cytology report to better guide clinicians in appropriate follow-up care and specialist referral. The ability to link the cytology procedure and report to patient management algorithms is immensely valuable for the patient and can be personally gratifying for the clinical cytopathologist. Cytologist-centered USFNA offers patients streamlined, cost-effective, and personalized care.

ROSE of FNA biopsy specimens helps ensure adequate samples for cytologic interpretation. A downside of ROSE is that either a cytotechnologist or pathologist must be on site in radiology or a clinic where the biopsy is performed, which can be a time-intensive endeavor [2]. Even though reimbursement for ROSE is offered, the reimbursement is low and valuable pathologist time is lost [3]. Additionally, if ROSE is undertaken by a cytotechnologist, critical decisions about triage of the specimen may not be possible. Cytopathologist USFNA is preferred over traditional paradigms in which the biopsy is performed by a non-pathologist because the imaging physician assigned to do the biopsy may not be skilled in USFNA. The physician may not understand the importance of sampling masses in specific areas to optimize the sample and could be resistant to suggestions about where to biopsy for optimum sampling. When not under the purview of a cytopathologist, slide smearing and specimen preparation can be poor when it is done by a person not acutely aware of the fragility of cells. A poor smear can sabotage all other aspects of the FNA procedure; therefore, this seemingly simple part of the process is often undervalued by those not intimately involved with specimen interpretation [4].

      Training

      To date, several didactic and hands-on courses are available to cytopathologists to learn USFNA. The College of American Pathologists’ AP3 multiday course covers topics including the basic physics of US, criteria for stratifying risk of malignancy of a lesion based on US criteria, techniques of needle placement using US guidance, importance and practice of specimen preparation and smearing, and medical coding. If the participant passes two practical examinations and a written exam, a certificate valid for 5 years is awarded for this accomplishment. Other learning venues include courses offered by The American Association of Clinical Endocrinologists (AACE). USFNA courses and poster presentations are now a part of meetings sponsored by the ASC, USCAP, CAP, and ASCP.

      Cytologists are eligible to apply for ECNU (Endocrine Certification in Neck Ultrasound) certification. For such certification, the candidate must pass the Comprehensive Certification Examination (CCE) and successfully complete the Validation of Competency Process (VCP). Cytologists who pass this rigorous curriculum may use the ECNU designation after their names.

      Taking a course in USFNA is just the beginning of learning the art of US-guided needle placement and correlating mass image characteristics resulting in an integrated cytologic diagnosis. Dedicated practice is needed since every patient can present a slightly different challenge to the aspirating physician, whether that be an anxious or non-compliant patient, body habitus, or location of the mass. Part of what makes USFNA an interesting and challenging endeavor is having to tailor each FNA procedure to the needs of the individual patient. Learning to target specific areas in a mass to within a few millimeters is an art. This takes practice, but when accomplished is very satisfying. The prescription is practice, practice, practice!

      US-Cytology Correlation

      The “triple-test” concept in breast FNA is not new to cytopathologists. Physical examination, imaging, and cytology findings all need to be taken into account for clinical guidance. Cytologist USFNA is an expansion of the “triple test” concept. Much can be learned about a mass to be sampled from its US characteristics: mass shape, margins, echogenicity, blood flow pattern, presence or absence of posterior acoustic shadowing, and characteristics of echogenic foci.

      US features of a mass impart a degree of “relative risk” which can be classified as favor benign, indeterminate, or suspicious for malignancy. The categorization of a mass based on US findings closely parallels what pathologists are already very familiar with based on experience with gross and microscopic pathology. Correlation of US images and cytology findings is of utmost importance. If the US findings are suspicious for malignancy but the cytology is benign, the cytologist needs to determine whether there is a sampling problem or why the US and cytology do not correlate. In the case of benign-appearing US features and malignant cytology, the same correlation needs to be done. For example, a well circumscribed mildly hypoechoic breast mass with posterior enhancement could be classified as favor benign or indeterminate by US criteria, but is a mucinous carcinoma by cytology; the cytologist knows that the results correlate. The cytologist is in the perfect position to understand why these processes have their particular US characteristics. With experience, the cytologist can even begin to predict what cytology will show based on the US features of the lesion. Radiologists, even with the availability of ROSE, do not get to so closely correlate US findings and cytology findings.

      Credentialing

      At the time of writing this chapter, there is no credentialing required in order for cytopathologists to perform and bill for USFNA. However, no one can predict the whims of insurers and thus this may change.

Fig. 1. USFNA exam room setup.

Cytopathologists may have to meet certain standards by their employers or institutions for whom they work [5, 6]. Institutional requirements may vary greatly, and it is hoped that the cytopathologist will be instrumental with helping to establish credentialing requirements.

      Equipment

      For a cytologist with an active FNA service, very little additional equipment is required when expanding their service to USFNA. There are numerous US machines available at various price points and features. Choice of a portable or floor model depends on personal preference. For USFNA of superficial masses, a linear high-frequency transducer is required. A small transducer footprint will allow for easier sampling of masses in the head and neck region. Unless a specialized feature such as elastography is desired, almost any modern US will meet the needs for a cytologist doing USFNA. When selecting an US machine, it is important that the buyer is comfortable with the image quality and ease of the user-machine interface. It is important to not only consider the purchase price of the unit, but also the warranty, cost of service contracts, use of a loaner unit if repair is required, and amount of time offered to train personnel in the use and setup of the machine.

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