Differential Diagnosis for Unilateral Tender Breast Mass in a Breast Feeder

• Single most likely diagnosis
  • Duct ectasia: This condition is characterized by the dilation of the milk ducts, often accompanied by inflammation and tenderness. The presence of a tender breast mass attached to the areola with many small cysts in a breastfeeding woman makes duct ectasia a strong candidate, as it is associated with breastfeeding and can cause the described symptoms.
• Other Likely diagnoses
  • Breast lactating adenoma: This is a benign tumor that can develop during pregnancy or lactation. It presents as a palpable mass and can be tender. Given the context of breastfeeding, this diagnosis is plausible.
  • Intraductal papilloma: Although less common, intraductal papillomas can cause a mass near the areola and can be associated with nipple discharge. However, they are typically not as tender as described and might not fully account for the multiple small cysts.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Inflammatory breast cancer: This is a rare and aggressive form of breast cancer that can mimic inflammatory conditions of the breast, such as mastitis or duct ectasia. It's crucial to rule out cancer, especially in the presence of a rapidly evolving or unresolving breast mass.
• Rare diagnoses
  • Fibroadenoma: While fibroadenomas are common benign breast tumors, they are less likely in this scenario due to their typical presentation as a painless, mobile mass, which does not match the description provided.
  • Other rare conditions such as breast abscesses or phyllodes tumors could also be considered but are less likely given the specific details of the case. Breast abscesses are usually more painful and fluctuant, and phyllodes tumors are rare and can be either benign, borderline, or malignant, presenting as a rapidly growing mass.