General Surgery (East Africa)
Objectives: To assess diagnostic accuracy of breast cytology through histological correlation and identify reasons for diagnostic pitfalls.
Methods: A total of 2700 cases were reported in cytology during the study period of 14 months, of which 1100 (40%) were from breast lesions. Only 96 (9%) cases had histological follow up in the form of core biopsy, lumpectomy and/or mastectomy. The cases in which cytology diagnosis did not match with histology diagnosis were reviewed by two pathologists and reasons for the diagnostic pitfalls in cytology were recorded. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of cytology were calculated.
Results: Seventy cases (73%) had no cytohistologic discrepancy, three cases were reported as unsatisfactory while 23(24%) showed discrepancy with histology. Interpretation errors occurred in 16 cases in 3 categories (benign C2, atypical C3 and suspicious C4). There were 2 false negatives (C2) and 14 false positives (C3 and C4). Majority (58%, 8 out of 14) of the errors in the false positive groups were due to the poor quality of smears received from our satellite centres. Misclassification of subtypes within benign and malignant categories occurred in 2 cases each due to overlapping features. Sampling errors occurred in three cases due to inherent nature of the lesion. Sensitivity of our FNA was 91%, Specificity was 79%, Positive predictive value (PPV) 59% and negative predictive value (NPV) was 96%.
Conclusions: There was no major discrepancy to influence the management or prognosis significantly. Minor discrepancies resulted due to sampling and interpretation errors. Poor quality smear emerged as a major cause of interpretation errors. This calls for corrective measures to be applied for both sample providers and pathologists.
Annals of African Surgery
(2011). Addressing the challenges of practicing breast cytology in a tertiary teaching hospital in Kenya. Annals of African Surgery, 7, 8-15.
Available at: http://ecommons.aku.edu/eastafrica_fhs_mc_gen_surg/23