Correlation between fine needle aspiration cytology (FNAC) and surgical biopsy in tissue diagnosis of breast lumps at Muhimbili national hospital, Dar Es Salaam, Tanzania

Abstract

Fine needle aspiration cytology (FNAC) is a fast developing technique in the management of palpable breast lumps in Muhimbili National Hospital (MNH). Literature evidence suggests that FNAC continues to play an important role in the management of patients with breast lumps worldwide. That triple test for palpable breast lumps yields high diagnostic accuracy and is cost saving. FNAC is part of a three stage diagnostic approach, and it is the most reliable fundamental element of the triple test, provided it is done by an experienced cytologist/pathologist. Previous studies compared FNAC with surgical biopsies and reported high sensitivity rates. However, positive predictive value, sensitivity and accuracy may vary from one institution to , another. OBJECTIVE: This study therefore, has been conducted in MNH to \ compare FNAC with open/surgical biopsy as the standard diagnostic technique, to determine the sensitivity, specificity, positive predictive value, negative predictive value and to asses the reliability of FNAC results in the management of palpable breast lumps. STUDY DESIGN: In this, prospective and retrospective study 200 breast lumps were investigated by FNAC. Subsequent open tissue biopsies, and specimens after mastectomies, were available for histological evaluation, for the same patients: The results of were evaluated and correlated to determining the accuracy of FNAC. The time span of the study was 24 months which commenced in April 1998 to April 2001. All FNAC were performed by pathologists, free handed without

V111 immaging accessories. RESULTS: There was a relatively high false negative rate 12.0% and the sample was inadequate in 2.5% cases. These resulted in a relatively low sensitivity 68.8%, positive predictive value of 85.5%, negative predictive value of 82%, and an overall accuracy of 83.1 %. In the majority of cases the FNAC report took two weeks. This attributed to the overwhelming demand for this service and waiting list of cases. The study showed several factors that probably contribute to the unsatisfactory findings that are presented. • Inadequate experience in aspirating, processing and interpreting smears. • Inadequate facilities, heavy patient load, financial constrains and unreliable supply of basic reagents like xylene, absolute alcohol, ether, glass slides, and cover slips that contributed to delay in definitive

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diagnosis. CONCLUSION: Fine needle aspiration cytology (FNAC) at the Muhimbili \ National Hospital cannot be relied upon as a standard modality of diagnosis in the management of breast lumps. FNAC should be seen not as a method, which stands alone, but one that complements one of the arms in the tripple technique, in the evaluation of a patient with a breast lump. Frozen section biopsy intraoperatively may still be necessary. However, the high specificity 98% obtained in this study may give satisfactory justification for surgeons to manage developing breast lesions, conservatively in adolescence. The lumps may be followed up for at least 6 months before excision if they do not disappear. It is therefore necessary that the shortcomings of FNAC be

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appreciated and corrective measures be undertaken to improve its accuracy. Thereafter recommendation for general clinical use in diagnosis of breast lumps may be implemented. RECOMMENDATIONS: Experience is not an inborn but an acquired quality. By introducing a special "Breast Lump Clinic" where pathologists surgeons, and students will fully participate and be trained depending on level of interest and financial availability may go a longway in improving the accuracy of FNAC. Aspirator performance should be regularly reviewed, and a feedback, be available for counseling and further training. Unless adequate cellular breast elements are identified, it is best to classify the smear as inadequate rather than negative. This practice will reduce the false-negative rate and contribute to the effectiveness of this diagnostic modality. Additional steps may be taken to ensure a reduction in the false negative rate: increasing the number of aspirates minimum three. Attention to technical preparation of the procured smears by avoidance of air drying and loss of cellular material. Knowledge of the clinical history age, physical and mammographic findings of the patient may assist the surgeon and pathologist in avoiding false-negative or unsatisfactory studies.