Phylloides Tumors (PTs) are rare breast neoplasms with a variable clinical course depending on the tumor category. The classification of PTs proposed by the World Health Organization (WHO) intobenign, borderline, and malignant is based on a combination of several histologic features, including stromalcellularity, nuclear atypia, mitotic activity, stromal overgrowth and tumor margin appearance. However, there areno defined criteria or clear cutoffs for individual histologicparameters. Thus, the diagnosis of PTs based on their integration of morphology remains challenging. Along with the grade, additional study of proliferative markers such as Ki 67 are essential to identify those with potential for aggressive behaviour. This study was undertaken to assess the histopathological characters and correlate Ki 67 expression in different subtypes of PTs.

In this study, 30 cases of PTs were studied regarding histologic features. Routine H&E stains were taken into consideration for diagnosis and classification of tumours. Immunostaining for Ki 67 was also performed by polymer based detection method. Ki 67 Labelling Index (LI) was categorised as 0-10, 11-30, 31-50, 51 and above depending on the percentage of positive tumor cells and was correlated with histologic grade and clinical features in each cases.

Twenty cases (66.7%) of Benign Phyllodes Tumour (BPT), 3 cases (10%) of Borderline PT, and 7 cases (23.3%) cases of Malignant Phylloides Tumor (MPT) were examined in this study. Among 20 cases of BPT, 3 cases (15%) were recurrent tumours.  Average Ki 67 LI in BPT was 5% (range 1-10%) and Borderline PT was 17.5% (range 15-20%). MPT exhibited Ki 67LI range of 15-35% with average LI of 25%. A significant association was seen between expression of Ki 67 in different grades of PT (P= 0.01). So, Ki 67 LI should be performed in routine histopathology reporting of phylloides tumour of breast for sub categorization

Aye Aye Khin is a renowned medical professional with a diverse range of accomplishments. Serving as the Rector for the University of Medicine (2) Yangon and the University of Pharmacy, Yangon, she is dedicated to shaping the future of medical education in Myanmar. Her extensive educational background includes degrees in MB.B.S, M.Med.Sc (Pathology), Dip.Med.Ed, and Ph.D. (Pathology) from the University of Medicine (1) Yangon. Khin's professional experience spans over two decades, with roles as a Professor, Head of Departments, and Director in various institutions. She has also been an active member of several prestigious committees and associations, including the Executive Committee of SEARAME, the Myanmar Medical Council, the ASEAN Association of Schools of Medical Technology, and the Australian Institute of Medical & Clinical Scientists. Her expertise in pathology, medical education, and leadership has significantly impacted the healthcare sector in Myanmar.