Breast Fine needle aspiration cytology (FNAC) is among the most regularly done FNAs worldwide. It had a long history of success in palpable and impalpable lesions using ultrasound guidance [10]. In underdeveloped and developing nations, breast lesions are one of the most frequently sampled areas by FNAC [9]. There were analytical issues experienced in interpreting breast cytology, particularly with untrained pathologists, and hence cytopathology training is required to remove these errors [9]. In breast FNAC, the "grey zone" contains a wide range of conditions ranging from benign conditions such as proliferative fibrocystic disease to sclerosing adenosis to malignant conditions like cancer [11]. A structured and uniform reporting system was required having cytological feature checklists for specific lesions based on an analytical approach that combines pattern recognition in low-power along with high-power cytological characteristics [12]. A "Breast Group" of cytopathologists, surgeons, surgical pathologists, radiologists, and oncologists were established by the “International Academy of Cytology Executive Council” in 2016 to promote the proper use of FNAC in breast lesions, improve the reporting system for breast FNAC, that increase communication between cytopathologist and clinical management team, and helps in further research into breast disease employing FNAC for the patient benefit [13].
The International Academy of Cytology (IAC) categorizes breast lesions into five categories, each with a clear definition and description, along with a specific risk of malignancy (ROM). The ROM is then linked with management recommendations. The system also emphasizes that breast FNAC relies on the expertise of those performing the biopsy, making slide smears, and interpreting material on the slides, and this requires good training and clear communication with clinicians for the management of patients with breast lesions [14].
Each of the five categories represents a distinct risk of malignancy was indicated for care by the breast group, and best-practice procedures were devised for each. The huge contrasts between developed and developing countries in terms of availability of imaging, core needle biopsy (CNB), surgical pathology, and management options were taken into consideration while doing this. The FNAC and CNB roles in the management algorithms will be included in these best-practice standards, which also consider the wide disparities in medical infrastructure [9].
According to the IAC Yokohama reporting system of breast cytology, 216 cases were included in the present study that underwent FNAC for breast lumps, and 48 of those who were confirmed by biopsy/ histopathology were divided into the five categories of the Yokohama system.
Slides that are insufficient or inadequate for a cytomorphological diagnosis include those smears that are too sparsely cellular (do not fulfill the criteria of adequacy) or too badly smeared or badly fixed.
Out of 19 cases included in the present study, 6 exhibited a histological link, and two were later found to be malignant. The ROM in our study was 33.3%, which was higher than studies done by Montezuma et al. [15] which was 4.8%, Wang et al. [8] (2.6%) and Tejeswini et al. [14] (22.22%), but similar to Hoda et al. [16]. Technical problems or the nature of the lesion may be the cause of insufficient FNAC. It was impossible to establish ROM since the yield, if not representative, would raise the risk of cancer.
Therefore, Wang et al. concluded that expertise with the aspirator, radiographic guided FNAC, instantaneous cytological assessment, and extra repeated aspirates via the Rapid On-Site Evaluation (ROSE) approach would all work together to reduce incorrect interpretation of insufficient samples [8].
Cases included in Category II have unmistakably benign cytological characteristics that may or may not indicate a particular benign lesion. Infections, inflammatory lesions, benign cysts, neoplasms, and epithelial hyperplasia fall within this group. This is the most common group in the present study, consistent with Montezuma et al. [15] and Tejeswini et al. [14]. 142 cases were included in this group. Out of 142 cases, no cases were malignant on histopathology. The ROM was 0%, which is less than mentioned in studies by Montezuma et al. [15] (1.4%) and Wang et al. [8] (1.7%) and Hoda et al. [16] (4.7%) and Tejeswini et al. [14].
The atypical group consists of cases with cytological characteristics that suggest micropapillary or cribriform proliferation, such as a single cluster of intact cells dispersed widely inside the nucleus, pleomorphism, high cellularity, necrosis, and complicated architecture.
In the present study, only 4 cases were included as atypical, out of which three have histopathological correlation, from which 1 case was found malignant. The ROM for this category was 33.3% which is significantly higher than in the studies done by Montezuma et al. [15] (13%) and Wang et al. [8] (15.7%) and Tejeswini et al. [14] but lower than Hoda et al. [16] (51.5%). This can be explained by the fact that there were fewer atypical cases in this study.
Triple correlation testing is employed to handle this group. If clinical and imaging data are normal, a review after a few months, preferably 3–6 months with or without FNAC, is advised; if suspicious or inconclusive, a core needle biopsy or excisional biopsy is suggested.
The cytological features of cells of suspected malignancy, most likely an in situ or invasive carcinoma, exhibit some cytological characteristics typically found in malignant lesions, but not enough of them, either in quantity or quality, to render a conclusive diagnosis of malignancy. Hence included in the category of suspicious of malignancy. There were only 6 cases in this category, out of which three were confirmed by histopathology; two of them were malignant on histopathological examination with a ROM of 66.7%. ROM for this category in the present study was low as compared to the study done by Montezuma et al. [15] (97.1%), while the ROM of Wang et al. [8] (84.6%) and Hoda et al. [16] (85.4%) and Tejeswini et al. [14]. This can be due to the minimal number of instances in this group in the present study.
There are specific cellular characteristics of malignancy in the malignant group. All of the incidents in this category were cancerous based on histology. The ROM was 100%, which is comparable to another study by Tejeswini et al. [14] (100%), Montezuma et al. [15] (100%), Wang et al. [8] (99.5%), and Hoda et al. [16] (100%). (98.7 percent). The present study's overall sensitivity, specificity, positive predictive value, and negative predictive value were comparable to those of investigations by Hoda et al. [16] Tejeswini et al. [14] Wang et al. [8], Montezuma et al. [15].
Limitations
As a tertiary care center situated in the capital of the state, it covers the usual population surrounding, which is usually urban, suburban, and near the peripheral area, but there is a huge periphery that remains unscreened under this study. Also, this study had a relatively smaller sample size, and the results may vary with a large study group. Lastly, the occurrence of the COVID-19 pandemic proved to be a hindrance as there was a limited inflow of patients during the study period. Ours is a small study group, resulting in a lack of statistical power; therefore, further studies with a large cohort, preferably multicentric, are needed along with proper follow-up to explore the role of the Yokohama system in reporting breast cytology.