Breast diseases encompass a wide pathological spectrum ranging from benign proliferative disorders of epithelial or stromal origin to malignant neoplasms, inflammatory conditions, and congenital anomalies. Among these, the most common presenting feature remains the presence of a breast lump, although in many cases, lesions are incidentally detected during imaging performed for unrelated reasons or during routine screening [1][2]. Breast cancer remains a major global health concern, and prompt, accurate diagnosis of breast masses is critical to ensuring effective management and reducing unnecessary surgical intervention [3]. The diagnostic evaluation of breast masses typically follows a triple assessment approach comprising clinical examination, imaging, and tissue sampling. Imaging modalities such as mammography, breast ultrasound and MRI help differentiate cystic from solid lesions and assess malignancy risk. Tissue diagnosis is achieved through fine-needle aspiration cytology (FNAC), core needle biopsy, or excisional biopsy. Core needle biopsy offer superior histological detail and is considered a gold standard in the diagnosis of breast masses. [4] In limited-resource settings, fine‑needle aspiration cytology (FNAC) offers a minimally invasive, cost‑effective diagnostic tool. FNAC has emerged as a cornerstone diagnostic modality for evaluating palpable and non-palpable breast lesions. Owing to its simplicity, rapid turnaround time, low cost, and minimal invasiveness, FNAC has become widely adopted in clinical practice for preliminary diagnosis of breast masses [1][2]. Its utility extends beyond diagnosis, contributing significantly to treatment planning, especially in distinguishing benign from malignant pathology. In several studies, FNAC has demonstrated high diagnostic accuracy, with reported sensitivity and specificity rates as high as 95% when performed under optimal conditions [2]. However, the diagnostic yield of FNAC is highly operator-dependent and can be influenced by factors such as lesion size, depth, and the quality of specimen obtained. In this context, ultrasound (USG) guidance has proven to be a valuable adjunct, especially for lesions that are small, deep-seated, or poorly defined on palpation. USG-guided FNAC allows for real-time visualization of the lesion and needle placement, improving sample adequacy and reducing false-negative rates [2]. Multiple needle passes from different angles under ultrasound guidance further enhance diagnostic yield, particularly in lesions that are cystic or located in anatomically challenging areas [2]. Given the paucity of region-specific data on the use of USG-guided FNAC in Western Rajasthan, this study aims to evaluate its diagnostic performance in assessing breast masses. By analyzing the cytomorphological spectrum of lesions encountered in our institution, we seek to determine the sensitivity, specificity, predictive values, and overall diagnostic accuracy of USG-guided FNAC in this geographic and clinical context. Additionally, this study will explore the role of ultrasound guidance in improving diagnostic precision and reducing sampling errors, especially in cases where conventional palpation-guided FNAC may be inadequate.

Study Design: This study is a hospital record based retrospective study. Study Place: The study will be carried out at the Department of Pathology and Department of Radiology, Government Medical College and Bangur Hospital, Pali. Study Period: The study was conducted for two years between Jan 2022 and Dec 2024. Study Population: Patients coming to the hospital with breast masses and underwent ultrasound guided FNAC and core needle biopsy or excision biopsy and the samples were sent to the Department of Pathology. All adequate and representative smaples from breast lesions received at Department of Pathology during the study period were included in the study. Inadequate, unfixed samples and smears and patients with incomplete clinical details were excluded. Method: The patients presented to the department for the evaluation of breast masses and were decided for an ultrasound guided fine needle aspiration. FNAC was conducted by a experienced pathologist along with a experienced radiologist for ultrasound guidance. The FNAC smears were properly fixed by 95% ethanol and stained with H&E and examined under light microscope. After the FNAC reporting the patients either underwent preoperative core needle biopsy or were operated and excision biopsy was done for histopathological examination. Biopsy samples were fixed in 40% buffered formalin and were processed as per protocol. The slides were stained with H&E stain and examined under light microscope. Clinical details of the patients were obtained from the requisition form or medical records, including age, habits, clinical examination, clinical diagnosis and noted in the predetermined format / proforma. The results of the FNAC reports and biopsy reports were corelated. Statistical analysis: The data was analyzed using appropriate statistical method. For data analysis Microsoft excel and statistical software SPSS v26 were used and data was analysed with the help of frequencies, figures, proportions, and measures of central tendencies. Sensitivity, specificity, positive predictive value, negative predictive values and accuracy of ultrasound guided FNACs were determined by comparing with core needle biopsy of excision biopsy taken as gold standard.

In the present study, A total of 71 cases were included in the study. The mean age of patients was 42.06 years (SD ±16.3), with a range from 16 to 77 years. Most patients (26.8%) were within the 21–30 years age group, followed by the 31–40 years group (22.5%). [Table no. 1] Lesions were slightly more common in the right breast (53.5%) compared to the left breast (46.5%). On Fine Needle Aspiration Cytology (FNAC) the diagnosis was benign in 74.6% (n = 53) of cases, malignant in 11.3% (n = 8), suspicious in 5.6% (n = 4), and unsatisfactory in 8.5% (n = 6). Histopathological examination confirmed benign lesions in 80.3% (n = 57) and malignant lesions in 19.7% (n = 14). The most frequent benign histopathological diagnoses were fibroadenoma (32.4%), mastitis (18.3%), and epithelial hyperplasia (11.3%). Among malignant lesions, ductal carcinoma predominated (15.5%), followed by lobular carcinoma (2.8%) and mucinous carcinoma (1.4%). [Table no. 2] The correlation between FNAC and histopathology revealed that among the 53 FNAC-diagnosed benign cases, 41.5% were fibroadenomas, 24.5% mastitis, 15.1% epithelial hyperplasia, 15.1% phyllodes tumor, and 3.8% were ductal carcinoma (false negatives). All 8 cases categorized as malignant on FNAC were confirmed as malignancies on histopathology—6 ductal carcinoma and 2 lobular carcinoma. Suspicious cases (n=4) also aligned with malignant findings on histopathology—3 ductal carcinomas and 1 mucinous carcinoma. [Table no. 3] Diagnostic Accuracy After excluding the 6 unsatisfactory cases on FNAC, the diagnostic performance of FNAC was assessed against histopathological results. When both “malignant” and “suspicious” FNAC results were considered positive: • Sensitivity: 85.7% • Specificity: 100% • Positive Predictive Value (PPV): 100% • Negative Predictive Value (NPV): 96.2% • Accuracy: 96.9% The Receiver Operating Characteristic (ROC) curve analysis demonstrated an Area Under the Curve (AUC) of 0.93, indicating excellent diagnostic performance of FNAC in distinguishing malignant from benign lesions. Table 1: Age group wise distribution of cases. Age Groups Frequency Percent 11 - 20 4 5.6 21 - 30 19 26.8 31 - 40 16 22.5 41 - 50 9 12.7 51 - 60 10 14.1 61 - 70 10 14.1 71+ 3 4.2 Total 71 100.0 Table 2: Histopathological diagnosis in the present study. Histopathology Diagnosis Frequency Percent Cystic lesion 2 2.8 Ductal Carcinoma 11 15.5 Epithelial Hyperplasia 8 11.3 Fibroadenoma 23 32.4 Fibrocystic Disease 3 4.2 Lobular Carcinoma 2 2.8 Mastitis 13 18.3 Mucinous Carcinoma 1 1.4 Phylloids Tumor 8 11.3 Total 71 100.0 Table 3: Correlation between diagnosis on FNAC vs histopathological diagnosis FNAC Diagnosis Histopathology Diagnosis Count Percent Benign Ductal Carcinoma 2 3.8% Epithelial Hyperplasia 8 15.1% Fibroadenoma 22 41.5% Mastitis 13 24.5% Phylloids Tumor 8 15.1% Total 53 100.0% Malignant Ductal Carcinoma 6 75.0% Lobular Carcinoma 2 25.0% Total 8 100.0% Suspicious Ductal Carcinoma 3 75.0% Mucinous Carcinoma 1 25.0% Total 4 100.0% Unsatisfactory Cystic lesion 2 33.4% Fibroadenoma 1 16.7% Fibrocystic Disease 3 50.0% Total 6 100.0%

The present study compared the ultrasound guided FNAC procedure for breast masses and it’s utility as a diagnostic tool for the diagnosis of breast masses. FNAC is a minimally invasive diagnostic technique, which does not require hefty laboratory set ups and technical expertise for preparation and staining. In the present study, the age of patients with breast lesions ranged from 16 to 77 years, with a mean age of 42.06 years. The most affected age group was 21–30 years (26.8%), followed by 31–40 years (22.5%). These findings are consistent with the demographic trend observed in multiple regional studies, where benign breast conditions are more prevalent in younger women, particularly those in the reproductive age group. Kamushaga et al. (2021) [5] conducted a study in a sub-Saharan African setting also demonstrated a younger patient population. The predominance of younger women in both studies likely reflects the high incidence of benign, hormone-sensitive breast conditions—such as fibroadenomas and mastitis—during the reproductive years. In contrast, the study by Agarwal et al. (2020) [6] reported a higher proportion of patients aged over 60, which may be due to inclusion criteria or geographic differences in healthcare-seeking behavior. On histopathological examination, benign lesions accounted for 80.3% of the cases in the current study, while malignant lesions comprised 19.7%, highlighting a benign-to-malignant ratio of approximately 4:1. The most common benign lesion was fibroadenoma (32.4%), followed by mastitis (18.3%) and epithelial hyperplasia (11.3%). Among the malignant cases, ductal carcinoma was the most frequent (15.5%), followed by lobular carcinoma (2.8%) and mucinous carcinoma (1.4%). These findings align with those of Cursi et al. (2020) [7], who reported fibroadenoma as the most common benign lesion in their analysis of over 8,000 small breast lesions. Similarly, Klijanienko et al. (1998) [8] noted that benign lesions such as fibroadenomas and hyperplastic changes were common in their cohort, although their population primarily included nonpalpable lesions. Kamushaga et al. (2021) [5] and Agarwal et al. (2020) [6] both reported ductal carcinoma as the predominant malignancy, consistent with the current study and with global epidemiological data on breast cancer. The predominance of benign pathology, particularly fibroadenomas, in younger patients is clinically significant, as it supports the role of less invasive diagnostic modalities such as ultrasound-guided FNAC, which can help avoid unnecessary surgical interventions in this population. Moreover, the identification of ductal carcinoma as the most frequent malignancy reinforces the importance of maintaining a high index of suspicion, especially in older patients or when imaging findings are atypical, regardless of age. The study demonstrates that ultrasound-guided fine needle aspiration cytology (FNAC) is a highly effective diagnostic tool in evaluating breast lesions, with a diagnostic sensitivity of 85.7%, specificity of 100%, positive predictive value (PPV) of 100%, negative predictive value (NPV) of 96.2%, and overall accuracy of 96.9%. These findings reinforce the utility of FNAC as a frontline, minimally invasive diagnostic modality, particularly when performed under ultrasound guidance. Our results are in line with previous studies that have assessed the diagnostic performance of ultrasound-guided FNAC. Klijanienko et al. (1998) [8], in a seminal study evaluating 654 nonpalpable breast lesions, reported a sensitivity of 87.8% and specificity of 94.5%, figures closely paralleling the present findings. They emphasized FNAC's reliability, particularly when excluding lesions with microcalcifications, suggesting that ultrasound guidance can optimize sampling precision and thereby enhance diagnostic yield. The high diagnostic values observed in our study also align with the large-scale retrospective analysis by Cursi et al. (2020) [7], which reported sensitivity of 97.4%, specificity of 99.6%, and accuracy of 98.5% for small breast lesions (≤1.0 cm). Their findings underscore FNAC's applicability not only in palpable but also in subclinical lesions, further validating its diagnostic robustness when paired with imaging. Similarly, Agarwal et al. (2020) [6] reported that FNAC had a sensitivity of 93.75% and specificity of 91.6% in diagnosing palpable breast masses, compared to higher performance metrics achieved by Tru-cut biopsy and the Triple Test. While core biopsy remains the preferred technique for histological subtyping and biomarker testing, especially in malignancies, the authors rightly concluded that FNAC continues to hold a valuable role in routine diagnostic workflows, particularly when rapid and cost-effective preliminary assessment is desired. More recently, Kamushaga et al. (2021) [5] directly compared ultrasound-guided versus conventional FNAC in a cohort of 354 patients with palpable breast lumps. Their findings indicated a perfect diagnostic performance of ultrasound-guided FNAC (100% sensitivity, specificity, PPV, and NPV), markedly superior to conventional FNAC, which yielded a sensitivity of 86.7% and specificity of 95.7%. Although our sensitivity was slightly lower (85.7%), our specificity and predictive values were comparable. This slight variance may reflect differences in population demographics, operator experience, lesion types, or cytological interpretation protocols. Nonetheless, the findings support the superiority of ultrasound-guided FNAC over blind techniques, particularly for ensuring accurate targeting and minimizing sampling errors. In our study, the absence of false positives and the limited number of false negatives (n = 2) further underscore the reliability of FNAC under imaging guidance. Importantly, all lesions categorized as "suspicious" on cytology were later confirmed as malignant on histopathology, supporting the clinical practice of managing suspicious FNAC results as potentially malignant. This approach contributes to the high PPV and NPV observed. Nonetheless, the 8.5% rate of unsatisfactory smears in this study underscores a known limitation of FNAC, even when performed under imaging guidance. Factors such as sampling error, low cellular yield, or the presence of fibrous or cystic components can compromise specimen adequacy. This is particularly relevant in patients with bulky breast tissue or in cases involving small, clinically non-palpable lesions, where accurate targeting may be more challenging. The diagnostic yield of FNAC is also highly dependent on the operator's experience; however, even with skilled technique, unsatisfactory smears may still occur due to the intrinsic nature of certain lesions. In such situations, repeating the FNAC or proceeding to core needle biopsy is advisable to ensure diagnostic accuracy. Taken together, our results affirm that ultrasound-guided FNAC is a highly accurate, specific, and reliable tool for the diagnosis of breast lesions, especially in resource-constrained settings where histopathological turnaround times may be delayed. While core needle biopsy offers additional histologic and molecular information, the high specificity and predictive values of FNAC support its continued integration into breast lesion diagnostic algorithms.

The present study demonstrates that ultrasound-guided fine needle aspiration cytology (FNAC) is a highly reliable, minimally invasive diagnostic tool for breast lesions. With excellent specificity (100%), high sensitivity (85.7%), and overall accuracy (96.9%), FNAC provides rapid and cost-effective results, particularly valuable in resource-limited settings. Fibroadenoma was the most frequent benign lesion, while ductal carcinoma predominated among malignancies. Although unsatisfactory smears remain an inherent limitation, repeat aspiration or core needle biopsy can overcome this challenge. Overall, FNAC under ultrasound guidance remains an effective first-line procedure in the diagnostic work-up of both palpable and non-palpable breast lesions.

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