PubMed · 8358142
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P R Wilson. 1993. Errors and artifacts.. https://pubmed.ncbi.nlm.nih.gov/8358142/
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The CLIA '88 regulations require the laboratory to review at least 10% of the gynecologic cases interpreted as negative that are examined by each cytotechnologist. The review must include negative cases selected at random and from patients identified as a high risk group. To evaluate the validity of this regulation, we reviewed the results of the 10% rescreen over a 24-mo period. The rescreening by pathologists detected epithelial abnormalities in 4/2,124 negative cases (0.18%). Subsequently, biopsy-proven squamous intraepithelial lesions were found in all four cases. Three different cytotechnologists were responsible for the four false-negative interpretations. Our results show that 10% rescreen of negative smears may detect a few false-negative cases. However, it is a time-consuming and inefficient mean to evaluate the performance of cytotechnologists. Quality control in gynecologic cytopathology is essential, but it is equally important that laboratories concentrate their resources and energy on methods proven to be effective.
During the last decade, biannual quality controls were performed in the Netherlands focusing on the immunophenotyping of leukaemic haematological malignancies. All results on 48 specimens obtained by 18-34 laboratories were analysed. The interlaboratory variability and percentages of discordant results from 30 markers were measured by assessing false positive or negative (cut-off 10%) results in comparison with median results of the group. The quality of the immunophenotypic diagnoses obtained from the interpretation of these markers in relation to clinical data was evaluated by scoring them as 'correct', 'minor fault', 'major fault', 'not based upon the markers used', and 'no diagnosis', CD3, CD8, CD19, CD61 and Sm lambda had the lowest percentage discordancy (sum of total negative and positive discordant values 5-7.5% of assays): CD13, CD15, cyCD22, CD33 and TdT scored worst with 14-20% cumulative discordancy. The analysis of each diagnosis yielded 78% acceptable immunophenotypic conclusions (correct 54% and minor fault 24%). It appeared that the major faults in immunophenotyping were caused by suboptimal antibody selection and erroneous interpretation of the results obtained, rather than by technical errors. Large differences per diagnostic category were observed, with the best scores for mature B-cell leukaemias, AMLs and common-ALL, and the poorest scores for T-cell malignancies which were correctly diagnosed in only 24-60% of specimens. Mature T-NHL and T-PLL were mistakenly diagnosed as T-ALL by 40% of the centres. Misinterpretation of TdT immunofluorescence or omitting this marker contributed significantly to these wrong diagnoses. A median of 4% of immunophenotypic diagnoses were not based on a correct panel of antibodies, but upon the morphology of the accompanying blood smear, and was often flawed by overinterpretation. In conclusion, both the technical performance of immunophenotyping of haematological malignancies in The Netherlands and the procedure by which a final diagnosis is obtained needs improvement, especially for T-cell malignancies.