Differentiation of Benign, Borderline and Malignant Phyllodes Tumor by Three Tiered Grading System

Background Phyllodes tumor are rare fibroepithelial neoplasm have a morphological spectrum from benign to malignant. The risk of local recurrence is more. The diagnosis of phyllodes tumor based on histology is important as histological grading correlates with prognosis. Materials and methods 14 cases of phyllodes tumor diagnosed in the Department of Pathology, Govt Vellore Medical College, Vellore. Phyllodes tumor are classified and histopathologically regraded as benign, borderline and malignant as per WHO 3 tiered grading system which includes stromal cellularity, cellular pleomorphism, mitosis, tumor margins, stromal overgrowth, heterologous stromal differentiation. Results Out of 14 cases 8 cases were classified as benign, 2 cases were classified as borderline, 4 cases were classified as malignant. One case diagnosed as benign phyllodes was classified and regraded as borderline phyllodes. Other case initially diagnosed as borderline phyllodes is classified and regraded as malignant phyllodes. Another case initially diagnosed as borderline phyllodes was classified and regraded as benign phyllodes. Conclusion Histological grading of phyllodes tumor as benign, borderline and malignant by 3 tiered grading system helps to achieve a correct diagnosis. Since stromal atypia, stromal overgrowth are independent predictors of clinical behavior. Histological features and grading was also useful in differentiating phyllodes tumor and fibroadenoma as the treatment and prognosis are different