Reply to Application of the Milan system for reporting risk stratification in salivary gland cytopathology

We would like to thank Pusztaszeri et al for their critical analysis of our recently published article.1 The category of atypia of undetermined significance (AUS) is not well defined in the Milan System for Reporting Salivary Gland Cytopathology.2 The cases we classified as AUS were those in which the differential was between a retention cyst (ie, a nonneoplastic lesion) and a low-grade mucoepidermoid carcinoma (ie, a malignant neoplastic lesion). Therefore, these cases were categorized as atypical because we were not sure even about the neoplastic nature of the lesion. Moreover, the images submitted demonstrated the most cellular areas identified after scanning all the smears prepared from the aspirate. Taking into account the overall picture of the entire sample and clinical details, we considered the atypical category to be the best fit. We agree that the follow-up histopathology was available in a fewer number of cases in our study,1 with only 2 cases classified under the AUS category, which could have lead to a discrepant risk of malignancy (ROM). Considering the very rare cases of AUS3 and the wide range (0%-73.08%)4 of ROM for the AUS category reported in various studies in the literature, it may be interpreted that the exact defining criteria for this category needs to be refined. The cystic lesions demonstrating the presence of benign epithelial cell clusters within a fluid or mucoid background were classified as benign cysts under the nonneoplastic category in our study1 and not as nondiagnostic or AUS as suggested. This was due to the fact that these cases fulfilled the adequacy criteria and did not demonstrate any atypia to classify them into the categories suggested. If we included these cases in the AUS category, the reporting rate of this category would then increase, which would not be appreciated by pathologists and clinicians because it does not provide a definite lead for patient management. Even members of the Milan group are concerned about the overuse of the term “AUS” as noted in other cytological systems and did not include this category in the survey questions to discover the respondent attitude toward it.2 We agree that the fewer number of histopathologically proven cases could have affected the ROM in the current study.1 We also agree with the statement regarding a higher number of nonparotid fine-needle aspiration specimens in our study compared with the literature, and a similar practice was always present in our institute, as depicted by our previous publication.5 A good number of cases of fine-needle aspiration cytology in our practice are referred from the radiotherapy department to rule out cervical metastases from head and neck primary tumors. This fact also explains the higher number of cases reported as benign salivary aspirates from subcentimetric submandibular swellings. To conclude, the findings stated in our study1 and others related to the Milan system could be beneficial in drafting the final Milan atlas, with an emphasis on the ambiguous categories. No specific funding was disclosed. The authors made no disclosures. Manish Rohilla, MD Nalini Gupta, MD, DNB Priya Singh, MD Arvind Rajwanshi, MD, FRCPath Research Department of Cytology and Gynecologic Pathology Postgraduate Institute of Medical Education Chandigarh, India