College of American Pathologists
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June 2005
PAP/NGC Programs Review

Q. Our laboratory maintains cytology/histology correlation in a separate file and keeps track of any discrepancies noted. We send out a letter to clinicians for all abnormal cytology cases without correlation asking for documentation of followup. We have several questions about these correlations: Should a comment on correlation be included in our pathology reports? When should requests for followup be made, and what should be done with this information?

A. CLIA ’88 mandates that there is laboratory comparison of clinical information, when available, with cytology reports and comparison of all gynecologic cytology reports with a diagnosis of high-grade squamous intraepithelial lesion (HSIL), adenocarcinoma, or other malignant neoplasms with the histopathology report, if available in the laboratory (either on-site or in storage), and determination of the causes of any discrepancies.1 These requirements are reflected in cytopathology checklist questions CYP.01900, CYP.07543, CYP.07556, and CYP.07569.2

The method for documenting the cytohistologic correlation results is not specified and is left to each individual laboratory’s discretion. Communication of cytology and biopsy correlation results to clinicians is key and provides critical information for optimal patient management.6 Cytohistologic correlation for individual patients can be documented in biopsy reports, via phone calls, or in letters, and, in more general terms, correlation statistics can be discussed in interdepartmental committees or conferences.

Evaluation of cytohistologic correlations is also an important part of a laboratory’s quality improvement program.10 The definition of what constitutes diagnostic discrepancy should be established, and it should be recognized that perfect correlation is not realistic. The 1996 CAP Q-Probes study5 of 22,429 paired cervicovaginal cytology and biopsy specimens reported a discrepancy rate of 16.5 percent with a Pap sensitivity of 89 percent and specificity of 65 percent. The majority of discrepancies in this study were due to sampling differences rather than screening or interpretive errors. Because both the Pap test and colposcopic biopsy are subject to sampling errors, reasons for discrepancies should be pursued when the biopsy is negative, as it may not always represent the gold standard. Negative cytology cases should also be reviewed, if available, when the biopsy is positive. Peer or multidisciplinary review or both of noncorrelating specimens may be helpful in achieving consensus. Regular summary and evaluation of results can identify trends and improvements.

There is no requirement for correlating biopsies with lesser abnormalities, for correlating subsequent cytology with previous biopsies, or for correlating concurrent biopsies. However, these cytohistologic correlations are recorded in many laboratories and may be a useful part of the quality improvement program. Laboratories are required to document the number of cases that do have histologic correlation in the annual laboratory cytology statistical report.

In a 1997 article by Andrew Renshaw, MD,7 the optimal time for correlation of cytology and subsequent biopsies was found to be between 60 to 100 days, during which time the correlation of the Pap test and the subsequent biopsies was the highest. Biopsies performed over 100 days were less likely to correlate with the initial Pap. The difference may be explained by regression of lesions over time.

When followup material is not available in the laboratory, documentation of followup correspondence or reports, telephone calls, or requests for information, whether as separate letters or in the histology report, must be maintained and kept for two years. In cases without biopsy followup, other studies such as human papillomavirus testing, repeat Pap tests, and colposcopic examination findings may provide useful information, especially in cases of HSIL, glandular abnormalities, and carcinoma.


1. Department of Health and Human Services, Centers for Medicare and Medicaid Services. Clinical Laboratory Improvement Amendments of 1988; final rule. Fed Register. 2003(Jan 24):3712 [42 CFR493.1274(c)(2)].

2. College of American Pathologists Laboratory Accreditation Program. Cytopathology checklist, January 2005.

3. Joste NE, et al. Cytologic/histologic correlation for quality control in cervicovaginal cytology. Experience with 1,582 paired cases. Am J Clin Pathol. 1995;103:32–34.

4. Tritz DM, Weeks JA, Spires SE, et al. Etiologies for non-correlating cervical cytologies and biopsies. Am J Clin Pathol. 1995;103:594–597.

5. Jones BA, Novis DA. Cervical biopsy-cytology correlation. A College of American Pathologists Q-Probes study of 22439 correlations in 348 laboratories. Arch Pathol Lab Med. 1996;120:523–531.

6. Wright TC, Cox JT, Massad LS, et al. 2001 consensus guidelines for the management of women with cervical cytological abnormalities. JAMA. 2002;287: 2120–2129.

7. Renshaw A, Granter SR. Appropriate follow-up interval for biopsy confirmation of squamous intraepithelial lesions diagnosed on cervical smear cytology. Am J Clin Pathol. 1997;108:275–279.

8. Hindman WM. An approach to the problem of false negatives in gynecologic cytologic screening. Acta Cytol. 1989;33:814–818.

9. Clary KM, et al. Cytohistologic discrepancies. A means to improve pathology practice and patient outcomes. Am J Clin Pathol. 2002;117:567–573.

10. Nakhleh RE, Fitzgibbons PL, eds. Quality Improvement Manual in Anatomic Pathology. 2nd ed. Northfield, Ill.: College of American Pathologists; 2002.

Margaret Havens Neal, MD
KWB Pathology Associates
Tallahassee, Fla.
Member, CAP Cytopathology Committee