Clinicoradiological Predictors of Malignancy in the Atypical Category by the Yokohama System for Reporting Breast Fine-Needle Aspiration Cytopathology

Introduction: The atypical category (AC) by the Yokohama system is an indeterminate group characterized by predominantly benign cytomorphology of the lesions, with some uncommon features that may be seen in malignancy in breast fine-needle aspiration. The risk of malignancy (ROM) varies from 13% to 25%. Its management depends on the clinical and radiological findings. Since most cases are benign, selecting cases for further management may benefit patients. This study aims to determine the clinicoradiological predictors for malignancy in AC breast cytology.

Materials And Methods: All AC breast fine-needle aspirations at Chiang Mai University Hospital from 2015 to 2019 were selected from an electronic database for cyto-histological correlation and ROM calculation. The clinicoradiological factors calculated by ROM were analyzed using multivariable logistic regression for malignant prediction and screening scores.

Results: There were 218 aspirates from patients aged 15-77 years. The lesion size ranged from 0.2 to 9.2 cm. The ROM was 27.5%. The significant predictors were age ≥40 years (P = 0.03), lesion size ≥1 cm (P< 0.01), and suspicious calcification on imaging (P < 0.01). The ROM was numerically increased in Breast Imaging-Reporting and Data System 5. The screening score showed 88.3% sensitivity, 55.1% specificity, 42.7% positive predictive value, and 92.6% negative predictive value.

Conclusions: The AC diagnosis varies from benign to malignant. Age ≥40 years, a lesion size ≥1 cm, and suspicious calcification/Breast Imaging-Reporting and Data System 5 are useful predictors of malignancy. Selecting cases according to screening scores can reduce invasive procedures by up to 43.1%.