Abstract: Desmoid tumors are rare tumors accounting for only 0.03% of all neoplasms. Mainly occurring in the fourth and fifth decades of life, these tumors originate in musculoaponeurotic tissues of the limbs, neck, trunk, abdominal wall, and mesentery. We present a rare case of a chest wall desmoid tumor that was mistaken for breast cancer on both physical examination and mammography, which highlights the unique risk these tumors present for confusion with other malignant processes. Although past literature contains numerous reports of other misdiagnoses, this case is unique in reporting the potential for misdiagnosis between chest wall desmoid tumors and breast cancer. In cases where suspicious breast findings do not correlate to usual diagnostic measures, such as fine-needle aspiration or core needle biopsy, the possibility of another pathology such as a chest wall desmoid tumor mimicking breast cancer should be considered in the differential diagnosis.