Neurofibroma of the breast is an extremely rare benign peripheral nerve sheath tumour, often associated with neurofibromatosis type 1 (NF1). It is even more uncommon in adolescents and when occurring as an isolated breast mass in the absence of systemic signs of NF1. This case report highlights an unusual presentation of a large solitary breast neurofibroma in an 18-year-old Nigerian female, emphasising diagnostic challenges and the importance of histopathologic confirmation. An 18-year-old female presented with a painless right breast lump that had rapidly enlarged over six months. There was no family history or other systemic signs of NF1. Examination revealed a large, multilobulated, mobile breast mass with visible surface veins. Breast ultrasonography showed a multilobulated mass with posterior acoustic enhancement and increased Doppler flow. A core needle biopsy revealed a diagnosis of diffuse neurofibroma. She underwent wide local excision with uneventful postoperative recovery. Isolated breast neurofibroma, particularly in adolescents without NF1, is rare and may mimic more common fibroepithelial tumours such as phyllodes tumours. Histopathologic examination with immunohistochemistry remains the diagnostic cornerstone. This report underscores the need for high clinical suspicion and contributes to the limited African literature on this rare entity.