Analysis of false negative cytology by a chromosome study

Diagnostic and prognostic significance of image cytometric DNA ploidy measurement in cytological samples of cervical squamous intraepithelial lesions

OBJECTIVE

To study the DNA ploidy pattern of uterine cervical squamous intraepithelial lesions (SILs) and its diagnostic and prognostic significance.

METHODS

The study included 31 cases of SIL: 11 low-grade (LSIL) and 20 high-grade (HSIL). Feulgen-pararosaniline staining was performed on previously Papanicolaou-stained smears and a DNA image cytometric study was performed. An internal reference was used to calibrate the samples.

RESULTS

All 31 cases of SIL, either LSIL or HSIL, were non-diploid. Of the 11 cases of LSIL, four were tetraploid and seven were aneuploid, whereas, of the 20 cases of HSIL, four were tetraploid and 16 were aneuploid. Stemline aneuploidy was not a significant discriminator between LSIL and HSIL (P=0.32). Based on single-cell analysis, HSIL cases had significantly higher DNA content than LSIL cases (P<0.01). When a mean of 30% or more was used for the 6c-exceeding event (6cEE) value, the sensitivity and specificity to indicate HSIL were 83% and 64%, respectively, with a positive predictive value (PPV) of 81% and negative predictive value (NPV) of 65%. All HSIL cases were cervical intraepithelial neoplasia grade 2 or worse (CIN2+) on biopsy. In addition, cases which showed recurrence had more DNA content by single-cell analysis than those with an indolent clinical behaviour: P=0.04 and P=0.03 for LSIL and HSIL, respectively.

CONCLUSIONS

Image cytometric DNA analysis is a useful technique for diagnostic and prognostic purposes in uterine cervical SIL when appropriate 'c' values are used in single-cell analysis. We propose that a >6c DNA content of 30% is useful as a cut-off level for predicting cases with CIN2+ in DNA image cytometry of cervical smears.