<b><i>Introduction:</i></b> We intend to determine the diagnostic power of fine needle aspiration biopsy (FNAB) for differentiation between malignant and benign lesions on axillary masses and draw the physicians’ attention to the benefits of FNAB cytology in the diagnosis of axillary masses. <b><i>Methods:</i></b> In this study, 1,328 patients with an axillary mass diagnosed by FNAB were retrospectively reviewed. These cases were registered at the affiliated hospital of Southwest Medical University (China), July 2014 to June 2017. Cytological results were verified either by histopathology following surgical resection or clinical follow-up. <b><i>Results:</i></b> Of the 1,328 patients affected by axillary masses, 987 (74.3%) cases were female, and 341 (25.7%) cases were male. The highest incidence of patients was in the age group of 41–50 years (375, 28.2%). There were 1,129 (85.0%) patients with benign lesions and 199 (15.0%) with malignant lesions. Of the 199 malignant lesions cases, 21 cases were lymphomas, 2 cases were accessory breast cancers, and 176 cases were lymph node metastatic tumors. Under lymph node metastases, the most frequent primary tumors were breast cancer (141, 80.1%), followed by lung cancer (21, 11.9%). According to the study, the characters of 1,328 cases showed statistically significant difference (χ<sup>2</sup> = 4.534, <i>p</i> = 0.033), and the incidence of females with axillary mass was significantly higher than that of males. There was a statistically significant difference in the distribution of benign and malignant cases in the patient age groups (χ<sup>2</sup> = 1.129, <i>p</i> = 0.000), and the incidence of patients of 41–50 years of age was significantly higher than that of other patients. The diagnostic accuracy of FNAB in axillary masses was analyzed with the results of 95.98% of sensitivity, 99.56% of specificity, 97.45% of positive predictive value, and 99.29% of negative predictive value. <b><i>Conclusion:</i></b> Our results confirm that FNAB is a valuable initial screening method regarding pathologic diagnosis of axillary mass, in particular with respect to malignancy in 41- to 50-year-old female patients.
Hypermetabolic Axillary Mass on 18F FDG PET/CT: Breast Cancer Arising from Accessory Breast Tissue