A Clinicopathological Study of Benign Phyllodes Tumour of Breast with Emphasis on Unusual Features.

INTRODUCTION Benign Phyllodes Tumours (PTs) are rare fibroepithelial neoplasms that resemble fibroadenoma. But unlike fibroadenoma, benign PT can recur and both stromal & epithelial components can progress to malignancy. Contrary to earlier belief that benign PT is a stromal neoplasm and possibly arises from fibroadenoma, more recent molecular studies have suggested that both stroma and epithelium can become neoplastic. Sometimes, benign PT can occur synchronously with fibroadenoma. Here histomorphologic analysis of eleven cases of benign PT are presented including some unusual features. MATERIALS AND METHODS Eleven cases of benign PT diagnosed between Dec 2014 and Jan 2016 in the Department of Pathology were studied. The demographic and clinicopathological features were analysed. RESULTS The most common age group affected was 20-30 years (range: 13-45). Clinical features included pain, lump and bleeding from nipple. The tumour size varied from 2.5-18 cm in diameter. H&E stained sections showed secondary changes (haemorrhage, myxoid, change, cystic degeneration), epithelial hyperplasia (8), squamous & columnar metaplasia (1), benign tubular adenoma like areas (1), Ductal Carcinoma In Situ (DCIS) (1), Invasive Ductal Carcinoma (IDC) (1), Pseudoangiomatous Stromal Hyperplasia (PASH) (1), histologic infarction (2), tumour necrosis (1) and synchronous fibroadenoma (1). Unusual histologic features included atypical ductal hyperplasia, DCIS, IDC, synchronous fibroadenoma and tubular adenoma like areas arising within benign PT. CONCLUSION This study shows a spectrum of hyperplastic, metaplastic, dysplastic, benign, in-situ-malignancy and even invasive ductal malignancy occurring in benign PT. Therefore adequate and extensive sampling is recommended for accurate diagnosis.