Multifocal Myxoid Neurofibromas of the Breast and Axilla in NF1: A Rare Imaging Presentation with a Previously Unreported Pathogenic Mutation - A Case Report

Abstract Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder characterized by multiple benign peripheral nerve sheath tumors, known as neurofibromas. While these typically involve cutaneous and subcutaneous tissues, breast parenchymal involvement is exceptionally rare. We present the case of a 51-year-old woman with genetically confirmed NF1 who developed multiple palpable masses in both breasts and axillary regions. Ultrasound demonstrated well-circumscribed hypoechoic lesions within the breast parenchyma and pectoral muscles, while magnetic resonance imaging (MRI) revealed lobulated, T2-hyperintense, mildly enhancing masses. A core needle biopsy of the largest axillary lesion confirmed myxoid neurofibroma. Further imaging showed systemic involvement. Genetic analysis revealed a rare pathogenic NF1 mutation, not previously reported in the literature. This case highlights the uncommon presentation of multifocal myxoid neurofibromas in the breast and axillary region and underscores the value of ultrasound and MRI in diagnosis and surveillance.