Queries and Comments

September 2005
Originally published in CAP TODAY

Stephen J. Sarewitz, MD

From the files of the CAP’s checklist-related questions. Answers reviewed by Stephen J. Sarewitz, MD, chair of the Checklists Committee and staff pathologist, Valley Medical Center, Renton, Wash.

Q. As of Sept. 30, 2004, the guidelines for use of negative controls in the performance of immunohistochemistry suggest a separate negative control for each block. Can our small tissue lab, which is limited to skin specimens, perform automated batch runs of a given antibody and use just one negative reagent control at the beginning or end, or both, of each batch?

A. There are two types of negative controls—negative tissue controls and negative reagent controls.

Negative tissue controls confirm the primary antibody's specificity. For this, one would use one or more tissues known to lack the target antigen—for example, a lab might use a leiomyoma and neuroma as negative tissue controls for keratin. Absence of staining confirms the specificity of the antibody. For negative tissue controls, it is appropriate to use one slide per batch staining run. The same holds true for positive tissue controls. The patient test slide, or the positive control, can serve as the negative tissue control if either contains cellular elements not expected to stain with the antibody. Best practice is the use of multi-tissue blocks containing an appropriate variety of control tissues as a combined positive and negative tissue control. Such blocks can serve as a permanent record documenting the sensitivity and specificity of every stain, particularly when mounted on the same slide as the patient tissue.

The negative reagent control is a section of patient tissue cut from the same paraffin block as the patient slide to be immunostained. This section is subjected to the same steps in slide preparation and staining, except application of the primary antibody. The purpose of the negative re a gent control is to exclude the possibility that some property of the patient tissue has caused nonspecific staining with the detection system applied. Because each tissue block may be different in this regard, there must be a negative reagent control slide for each paraffin block that is stained in the run. For example, if you are examining a large congenital nevus with HMB-45 and you stain blocks 1A, 1B, and 1C, you must run a corresponding negative reagent control slide for each of those three blocks.

Q. For which immunohistochemical reagents is the medical director allowed to extend the outdate?

A. The laboratory must follow the manufacturer's recommendations for shelf life, storage, and use of materials.

The Federal Register prohibits the use of expired materials. The laboratory can refer to the Jan. 24, 2003, Federal Register (7164 [42CFR493.1252(d)] for more information. The federal regulations are also available at www.phppo.cdc.gov/clia/regs/toc.aspx.

The only exception to this federal regulation is in blood banking with rare antisera, where the anti sera may be used beyond the expiration date, but only after stringent quality control demonstrates that the material is still performing properly.

Q. We were recently inspected and asked to implement a quality management program. Can you tell me specifically what the CAP inspector is asking for? We check Pap results with biopsy specimens and watch for more than one-step differences with Paps and biopsy results.

A. The CAP does not provide detailed requirements and guidelines for a quality improvement plan in cytopathology because a program can be designed a variety of ways, which are left to the discretion of the individual laboratory. The suggestions presented in the general chapters of the CAP Quality Improvement Manual in Anatomic Pathology, including chapters two and three, apply to cytology. Furthermore, a sample of a cytopathology quality improvement plan is provided in the cytopathology chapter, page 95 of the second edition (table 16).

In brief, the laboratory should monitor quality indicators to look for trends or problems. Quality indicators include such data as turnaround time, ASC/SIL (atypical squamous cells/squamous intraepithelial lesions) ratio, 10 percent quality control rescreening data, cytotechnologist-cyto pa thol ogist correlation, overall laboratory abnormal rates, comparison of the percentage of each diagnostic category reported by each screener with the overall laboratory percentage, and several other parameters that are described in a variety of sources, including the CAP checklist, CLIA regulations, and the aforementioned quality improvement manual. It is useful to include comparisons with national benchmark data, such as abnormal rates for gynecological cytology published in the CAP checklist and CAP interlaboratory comparison program. The laboratory should follow trends in data, establish appropriate thresholds, and take corrective action when a problem is identified. Other elements of quality improvement can include continuing education activities and other activities performed in the laboratory that improve laboratory quality.

Whatever plan you devise, it is important to document monitors, take corrective action when appropriate, and review the plan periodically to determine if it needs to be updated.

Q. I am trying to interpret cytopathology checklist question CYP.05316 and explain to one of our pathologists what is expected and when his name should appear on the report. The pathologist has been skeptical of our cytology department since he lost his own cytologist in an acquisition. Therefore, he has asked our cytology department to send him all negative slides for his group of clients before releasing results. He claims he does not thoroughly rescreen negative Pap tests. I think he randomly reviews slides to check the quality of work performed by our cytologists. If he randomly, and sometimes less than thoroughly, reviews slides, should his name appear on the report?

A. Yes, the pathologist's name should be on the report in this situation. Recent litigation has raised awareness of this issue and led to publication of the aforementioned checklist question as well as articles in the literature. Basic requirements for signatures on reports are straightforward and sensible. The report should clearly identify all individuals who have reviewed the slides and should not include the name or signature of anyone who has not reviewed the slides.

The term "review" may reflect different practices by technical supervisors in different laboratories—for example, rapid rescreen, complete rescreen, or other. However, looking at a slide prior to release of the report should clearly be considered review of the case and would require the name of the physician reviewer on the report. Retrospective review after the report has been sent would not require the name of the reviewer on the report.

The CAP cytopathology checklist requires that a pathologist review all cases with reactive or reparative changes, atypical cells, cells indicative of a squamous intraepithelial lesion, and cells suspicious for or diagnostic of malignancy, and that the name or signature of the reviewing pathologist be clearly identified on the report. The cytology records should also clearly indicate others who have reviewed the slides. Cytotechnologists should be identifiable by name, initials, or another identifier in laboratory records. Cytotechnologists' names are not required but may be included in reports. It is important that a pathologist's name or signature never appear with the diagnosis on negative Pap reports unless he or she has personally reviewed the slides.

Legal issues remain for pathologists who have their name on a report. If a Pap case comes to litigation, they will likely be named in the suit. Although the medical director's name may appear on the report, it should not be associated with the diagnosis unless the director evaluated the case. The medical director's name must be clearly differentiated from the name of those who reviewed the slides.

For more information on this subject, see the CAP TODAY article "Whose name should go on this report anyway? Protecting ourselves and our practices in the current legal environment" (Neal MH. 2004; 18[8]:56).

Q. I am working on a request from a pathologist regarding benchmarking for histology technical staff. Is there any data, resource, or other tidbit of information that may be helpful?

A. No information is available at this time; however, a joint pilot study program is being developed by the National Society for Histotechnology and the CAP to collect and study such data for benchmarking purposes.