Background: Nodular fasciitis of the breast is a rare be-nign pathology that can mimic breast cancer clinically, radiologically, and histopathologically. Case Report: An 18-year-old female patient had first visited a physician in a different center with the complaint of a lump in her left breast. Breast examination had revealed a palpable mass located in the left upper outer quadrant. Ultrasonography had demonstrated a hypo-echoic lesion. Excisional biopsy of the lump had been performed and histopathologic examination misdiagnosed this lump as a mesenchymal tumor. The patient was then referred to our clinic for further investigations. Pathologic revision was performed and the diagnosis of nodular fasciitis of the breast was established. Conclusion: Awareness of this rare clinical entity, nodular fasciitis, in the breast eliminates the misdiagnosis of breast cancer.