Co-existence of Multifocal Ductal Carcinoma in Situ with Microinvasion and Benign Phyllodes Tumour in the Same Breast: A Rare Case Report

The presented case is a rare instance of multifocal Ductal Carcinoma In Situ (DCIS) with microinvasion in the presence of a benign phyllodes tumour in a 60-year-old postmenopausal woman. The patient reported that she had painless right breast lumps for four months and no previous trauma, hormonal treatment or family history of breast/ovarian carcinoma. A physical examination showed four discrete, mobile and non-tender masses without any skin changes or lymphadenopathy. Biochemical and haematological investigations were unremarkable. Mammography and targeted ultrasound imaging showed several heterogeneous nodules, one of which was lobulated fibroepithelial with the rest being segmental calcifications, which led to suspicion of multifocal DCIS with microinvasion. Wide local excision of all nodules was done. Histopathology also confirmed DCIS with microinvasion in three nodules and one benign phyllodes tumour, without having epithelial malignancy. This case underlines diagnostic challenge in coexisting DCIS and phyllodes tumours, emphasising the importance of proper imaging, surgical excision and histopathology for diagnosis and management of such rare cases.