RESUMEN
INTRODUCTION: Mucinous carcinoma is a variant of invasive breast carcinomas representing 2% of them. These tumors frequently develop in postmenopausal females; it is a rare histological variant in young patients. CASE PRESENTATION: A 25-year-old female refers a slow growth mass of 2 years of evolution. Excisional biopsy reveals a pure mucinous carcinoma with positive hormone receptors and negative HER2. She was treated with hormone therapy and surgical resection. DISCUSSION: Mucinous carcinoma is a rare variant reported in young patients. Many series report that is frequently found in postmenopausal patients. We present a case of a pure mucinous carcinoma in a 25-year-old female with the importance of being a low-frequency malignancy in young patients. CONCLUSION: Due to its benign course, it is important to know that this lesion can also present in young patients. The importance underlies in the multidisciplinary management at the right time in a proper way.