The Conundrum of Papillary Breast Lesions within the C3 Category

Risk Stratification of Breast Fine-Needle Aspiration Biopsy Specimens Performed without Radiologic Guidance by Application of the International Academy of Cytology Yokohama System for Reporting Breast Fine-Needle Aspiration Cytopathology

BACKGROUND AND OBJECTIVE

The International Academy of Cytology (IAC) Yokohama system for reporting breast fine-needle aspiration biopsy (FNAB) cytopathology has been proposed to standardize breast FNAB reporting. The aim of this study was to categorize breast FNAB cases performed by palpation without radiological guidance according to the IAC system, establish the risk of malignancy (ROM) for the categories and assess the system's utility, pitfalls, and implications in low-resource/financial constraint settings.

METHODS

A retrospective analysis of palpation-guided FNAB of breast lesions performed without radiological guidance between January 2016 and December 2019 was carried out and was correlated with follow-up biopsies wherever available. A total of 1,089 cases were recategorized using the IAC Yokohama system. Histopathology follow-up was available for 400 cases. The data were analysed for ROM, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS AND DISCUSSION

Out of 1,089 cases, 4.3% (n = 47) cases were categorized as insufficient, 82% (n = 893) as benign, 2.8% (n = 31) as atypical, 2.7% (n = 29) as suspicious of malignancy, and 8.2% (n = 89) as malignant. Some 400 cases had a follow-up biopsy, based on which, the ROM for the categories were 33.3%, 0.4%, 37.5%, 96%, and 100%. The NPV for the benign category was 99.6%. The PPV of the malignant category was 100%, that of combined suspicious of malignancy and malignant categories was 99%, and of combined atypical, suspicious of malignancy, and malignant was 90.6%.

CONCLUSION

The IAC Yokohama system is useful in standardizing the reporting of cytopathology of breast lesions. FNAB with radiological guidance is ideal but in cases of finance/resource constraints, FNAB by palpation alone is satisfactory if the test result is in the benign, suspicious of malignancy, or malignant categories, which constitute 91.5% of the cases in this study. A repeat ultrasound-guided FNAB and/or core needle biopsy should be recommended for cases in the insufficient/inadequate or atypical categories.

Papillary lesions of the breast: A systematic evaluation of cytologic parameters

BACKGROUND

The cytologic diagnosis of papillary lesions of the breast is challenging because of the diverse morphology, including epithelial hyperplasia, atypia, low-grade malignancy, and neuroendocrine differentiation; also, traditional malignant features such as necrosis and myoepithelial cell loss can be lacking. Thus, the diagnostic criteria for papillary lesions may differ from those for other breast lesions. This study evaluated various cytologic parameters in a large cohort to identify useful diagnostic features.

METHODS

Cytologic preparations of papillary lesions with histologic follow-up were reviewed for features related to cellularity, epithelial cohesiveness, cellular and stromal architecture, cytomorphology, and background. Corresponding histologic slides were also reviewed.

RESULTS

In all, 153 cases were included. Epithelial discohesion, solid and cribriform patterns, atypical nuclear features, and mitoses (P ≤ .001 to P = .017) were associated with malignancy. Cell balls, monolayer sheets, and features of cystic change (P < .001 to P = .016) were associated with benign lesions. Complex (P = .031) and slender (P = .026) papillae and neuroendocrine features (P < .001) were associated with malignancy. Hemorrhage, background, and infiltrating neutrophils (P < .001 to P = .025) were associated with malignancy; fibrotic broad papillary stromal fragments (naked papillary fronds [NPFs]; P = .043) were associated with benignity. The presence of any single parameter, including the absence of myoepithelial cells within epithelial structure, the presence of cytoplasmic granules, an increased amount of cytoplasm, and a nuclear to cytoplasmic (N/C) ratio greater than 0.7, which were identified by principal component analysis, yielded a sensitivity of 95.1% and a specificity of 100.0% in predicting malignancy.

CONCLUSIONS

Methodological assessment of multiple features is recommended. Myoepithelial cells, cytoplasmic granules, the amount of cytoplasm, and the N/C ratio are key features for diagnosis.

Atypical aspirates of the breast: a dilemma in current cytology practice

Aims

The probabilistic approach is widely adopted for breast fine needle aspiration cytology. However, a definite cytological diagnosis is not always possible for C3 (atypia) cases, which poses a management dilemma as this represents a mixed category of benign and malignant cases. It would be beneficial to be able to predict malignancy based on specific cytological features in C3 aspirates.

Methods

A comprehensive panel of cytological features (including quantitative, cytomorphological and background features) in a large cohort of C3 breast aspirates with subsequent histological excisions was evaluated to identify relevant morphological criteria predicting the risk of subsequent malignancy.

Results

A total of 229 C3 specimens with histological follow-up were included. Malignant outcome was found in 30.1% of specimens and the majority were invasive cancers. Features that showed a significant association with malignant outcome included older age (p=0.001), lower percentage of epithelial cell clusters and high percentage of single cells (p=0.002), cribriform architecture in cell clusters (p=0.034), presence of intracellular mucin (p=0.027), increased cell clusters without myoepithelial cells (p=0.048), diminished fibromyxoid stromal fragments (p=0.001), reduced bipolar nuclei (p=0.021) and the presence of necrosis (p=0.023). Except for the percentages of single cells and cell clusters without myoepithelial cells, all other features were shown to be independent risk predictors in multivariate analysis.

Conclusions

C3 aspirates were associated with a significant probability of histological malignancy. Certain quantitative, cytomorphological and background features were potentially helpful in predicting the risk of a malignant outcome. The prediction could be clinically useful in the management of C3 cases.