At our institution, 17% of cervical conization specimens are reported as negative for dysplasia or malignancy. To identify sources of error, we reviewed 53 negative conization specimens and their prior and follow-up cytology, biopsy, and endocervical curettage specimens. Examination of deeper-level sections and p16 immunostaining were performed on all conization specimens and selected biopsy specimens. Dysplasia was detected in 26% (14/53) of conization specimens. Twenty-eight percent (15/53) of cones were truly negative, and the presurgical material had been overcalled as high-grade squamous intraepithelial lesions (HSIL). Forty-five percent (24/53) of cones were truly negative and HSIL was confirmed in the presurgical material. Of these, 11% (6/53) showed subsequent evidence of residual dysplasia and 26% (14/53) were negative on further follow-up. Deeper-level sections, p16 immunostains, and consensus review may help identify squamous dysplasia in conization specimens and may prevent the overdiagnosis of HSIL on cervical biopsies.

The histologic and/or cytologic follow-up of 127 cases of cervical lesions termed "squamous intraepithelial lesion of indeterminate grade" (SIL) on Papanicolaou (Pap) smears by the 2001 Bethesda System was compared with 150 control cases of low-grade SIL (LSIL), high-grade SIL (HSIL), and atypical squamous cells, cannot exclude HSIL (ASC-H). A follow-up diagnosis of cervical intraepithelial neoplasia (CIN) 2 or higher was identified in 22.8% of SIL cases, which was 2.6 times higher than LSIL, 3 times lower than HSIL, and 1.5 times lower than ASC-H. A follow-up diagnosis of CIN 1 was identified in 31.5% of SIL cases, which was 2 times lower than the LSIL group, 1.5 times higher than the ASC-H cases, and 1.8 times higher than the HSIL group. We found that 22.0% of cases diagnosed as SIL were followed up by Pap smears rather than colposcopy and biopsy, compared with about 1% of LSIL and HSIL cases. Because SIL cases have a significant risk of harboring CIN 2 or greater, we recommend follow-up by colposcopy and biopsy.

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