College of American Pathologists
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  PT performance of HSV, Candida challenges


CAP Today




May 2009
PAP/NGC Programs Review

Mary R. Schwartz, MD

Negative cervicovaginal slides with herpes simplex virus and Candida are among the most readily validated (robust) of the reference diagnoses in the CAP Interlaboratory Comparison Program in Cervicovaginal Cytopathology, or Pap program. Since gynecologic cytology proficiency testing was instituted, performance of challenges with both of these infections has worsened. In a series of two papers, Moriarty, et al. examined the change in performance to see if it was due to participants not recognizing cytologic features or their “gaming” of proficiency testing.

The seroprevalence of herpes simplex virus, or HSV, has decreased in the U.S. and by inference the incidence of HSV infection. Moriarty, et al. (In: Performance of herpes simplex challenges in proficiency testing. Observations from the College of American Pathologists proficiency testing program. Arch Pathol Lab Med. In press.) found a significant difference in the diagnosis of HSV in PT compared with graded challenges before PT (96.6 percent versus 98.6 percent, P<.001). However, there was no difference in the performance of educational challenges pre- and post-PT. The authors conclude that the decreased performance is not due to lack of recognition of cytologic changes of HSV secondary to the decreased prevalence of HSV infections.

Cellular changes associated with Candida include nuclear enlargement, hyperchromasia, orangeophilia, and perinuclear halos. Moriarty, et al. (In: Performance of Candida—fungal-induced atypia and proficiency testing. Observations from the College of American Pathologists proficiency testing program. Arch Pathol Lab Med. In press.) found that these cytologic changes are correctly identified as reactive changes in educational settings, but are upgraded in the testing venue. The performance of field-validated Candida challenges fell from 98.3 percent correct responses pre-PT to 97.2 percent post-PT (P<.001). After implementation of PT, 79.7 percent of incorrect diagnoses for field-validated slides were category C (LSIL) as compared with 59.5 percent before PT (P<.001). Candida challenges performed better in the educational component post-PT than pre-PT.

Both papers conclude that PT adversely affects the performance of participants in the identification of negative slides with HSV and Candida. The change in performance of challenges with these infections appears to most likely be due to test-taking strategies rather than the participants not recognizing cytologic features. The cytologic changes associated with these infections may be defensively upgraded in PT to avoid loss of points for missing a possible dysplasia.

Dr. Schwartz, a member of the CAP Cytopathology Committee, is director of anatomic pathology, The Methodist Hospital, and clinical professor of pathology, Baylor College of Medicine, Houston.