The borderline cervical smear: colposcopic and biopsy outcome

To review the outcome of women referred with smears showing borderline nuclear change (BNC), and to determine any differences in outcome if BNC was persistent, preceded by dyskaryosis, or followed treatment for cervical intraepithelial neoplasia (CIN). In addition, to determine criteria that might permit delineation of a BNC subtype, predictive of CIN.

The records of 178 women referred for colposcopy in 1993, with last smear showing BNC, were obtained from our laboratory database. The cytology, colposcopy, and biopsy follow up for a five year period were also obtained. The patients were divided into three categories according to their smear status before the last referral borderline smear: category 1, persistent BNC (n = 39); category 2, BNC preceded by dyskaryotic smears (n = 100); and category 3, BNC after treatment for CIN (n = 39). The referral borderline smears were reviewed on cases with negative outcome and those with a biopsy diagnosis of CIN2 and CIN3.

In 50 women (28%) no biopsy was deemed necessary after colposcopic assessment. The biopsy results in the remaining 128 (72%) women were as follows: normal in 18 (10%), koilocytosis in 12 (7%), CIN1 in 45 (25%), CIN2 in 32 (18%), and CIN3 in 21 (12%) women. High grade lesions (CIN2, CIN3) were seen on biopsy in 14 of 39, 33 of 100, and six of 39 cases in category 1, category 2, and category 3, respectively. Blind review of the referral borderline smears from 53 women with a biopsy diagnosis of high grade lesions (32 CIN2, 21 CIN3) confirmed they were borderline in 23, upgraded them to mild dyskaryosis in 15, and found that 14 cases of isolated moderate or severe dyskaryotic cells had been missed originally. The borderline change was in mature squamous cells in five of 23 and in immature metaplastic epithelium in 18 of 23 cases. After smear review in 68 women with negative outcome, 36 smears were reclassified as negative in keeping with inflammation and atrophy, three were considered unsatisfactory, one was upgraded to CIN1, and 28 were confirmed as BNC. Of the latter, 25 of 28 were in mature squamous cells. The five year follow up on women with negative colposcopy (n = 50), negative loop excision of transformation zone (LETZ) (n = 18), and LETZ with koilocytosis (n = 12) showed subsequent high grade CIN on LETZ in 16, 0, and two patients, respectively.

On referral of women for colposcopy with last smear showing BNC, the outcome was high grade CIN in over 30% of cases, irrespective of whether the borderline smear was preceded by another borderline smear or by a dyskaryotic smear. In contrast, in those referred because of BNC after treatment of CIN, high grade CIN was seen less frequently (15% of cases). Furthermore, in cases that necessitated loop excisions, high grade CIN was seen in 41%. This study also showed that BNC associated with inflammation or atrophy, or BNC in mature squamous cells, appears to have lower predictive value for CIN than those cases where BNC is associated with immature metaplastic epithelium. The use of terms such as "BNC favour reactive" for the former and "BNC favour dyskaryosis" for the latter is recommended, together with follow up by cytology and colposcopy, respectively.