Running Title: Imaging Features of Breast Carcinoma in Neurofibromatosis Type 1 Received: June 12, 2019; Accepted: January 13, 2020 Multimodality Imaging Features of Breast Carcinoma in Women with Neurofibromatosis Type 1 (NF 1) – A Report of Two Cases

With a prevalence of approximately 1 out of 2,500 to 4,000 births, neurofibromatosis type 1 (NF1), also known as von Recklinghausen’s disease, is one of the most prevalent autosomal dominant diseases in humans. There is fourto five-fold increased risk of malignancy in these patients due to the presence of NF1 gene mutation which is a tumour suppressor inhibiting RAS activation. NF1 is known to be closely associated with central nervous system (CNS) tumours; however, its association with other non-CNS malignancies is not uncommon. Mutation of BRCA1 (breast cancer 1, early onset) and BRCA2 (breast cancer 2, susceptibility protein) genes has long been recognized as an important risk factor for the of breast cancer. Incidentally, breast cancer 1 (BRCA1) and NF1 genes are both located in the long arm of chromosome 17. The association between NF1 and breast cancer has long been debated; recent studies, on the other hand, have established this association, with NF1 unequivocally identified as breast cancer susceptibility gene conferring a moderate risk of breast cancer development. In this report, we described multimodality imaging features related to two female cases of breast cancer with NF1; we further reviewed the literatures on the association between NF1 and breast cancer and its diagnostic challenge.