THE INCONCLUSIVE POSSIBLE HIGH-GRADE EPITHELIAL ABNORMALITY CATEGORY IN PAPANICOLAOU SMEAR REPORTING

BACKGROUND. The Australian Terminology for Cervical Cytology Reporting includes the category ''Inconclusive-Possible high grade epithelial a bnormality.'' METHODS. The frequency of use of this category, the type s of associated cell patterns, and the yield of high grade lesions at biopsy were studied. RESULTS. One hundred and two cases categorized as ''Inconclusive'' were reported between January and June 1995, represe nting 0.24% of 41,712 Papanicolaou (Pap) smears screened. The abnormal cells were reported as squamous in 74.5% of cases, endocervical in 4. 9% of cases, endometrial in 3.9% of cases, and indeterminate in 16.7% of cases. The main cellular patterns included disorganized groups of h yperchromatic squamous, glandular, or indeterminate cells (64.2% of ca ses) and atypical metaplastic squamous cells (28.4% of cases). Cell pr eservation was suboptimal. In 25.3% of cases the cells were highly deg enerate or air-dried. Follow-up included biopsy (84.3% of cases), colp oscopy alone (7.8% of cases), and repeat Pap smears without any detect ed abnormality (3.9% of cases). No follow-up was available in 3.9% of cases. High grade abnormalities were found in 66.3% of the biopsied ca ses and 55.9% of the total cases (48 cervical intraepithelial neoplasi a [CIN] of Grade 2 or 3; 2 squamous cell carcinomas; 3 endocervical ad enocarcinoma in situ [ACIS]; 3 adenocarcinomas of endocervical, ovaria n, and endometrial origin; and 1 endometrial stromal sarcoma). In 16.2 % of cases a low grade squamous lesion was present on biopsy (CIN, Gra de 1 or human papillomavirus effect); and no lesion was found in 17.4% of cases. CONCLUSIONS. The ''Inconclusive'' category was not overused , and gave a high yield of biopsy abnormalities. Accepting uncertainty in the diagnosis of some high grade lesions reduces their likelihood of being classified incorrectly as reactive changes, ignored because o f poor cell presentation, or lost in the larger group of classificatio ns such as atypical cells of undetermined significance, borderline nuc lear abnormality, or non-specific minor changes. Cancer (Cancer Cytopa thol) 1998;84:208-17. (C) 1998 American Cancer Society.