Differential Diagnosis for Pus Coming Out of the Breast Nipple

• Single Most Likely Diagnosis
  • Mastitis: This is an infection of the breast tissue, which can cause pus to be expressed from the nipple. It's commonly seen in lactating women but can also occur in non-lactating women. The presence of pus indicates a bacterial infection, making mastitis the most likely diagnosis.
• Other Likely Diagnoses
  • Breast Abscess: A localized collection of pus in the breast tissue, which can cause nipple discharge, including pus. It often requires drainage.
  • Ductal Ectasia: A condition where the milk ducts in the breast become widened, leading to a blockage. This can cause a thick, greenish, or black discharge, which might be mistaken for pus.
  • Periductal Mastitis: Inflammation of the ducts under the nipple, often associated with smoking. It can cause nipple discharge, including pus, and nipple retraction.
• Do Not Miss Diagnoses
  • Inflammatory Breast Cancer: A rare and aggressive form of breast cancer that can cause symptoms similar to mastitis, including redness, swelling, and warmth of the breast. It's crucial to rule out cancer in cases of persistent or severe infection.
  • Tuberculosis of the Breast: Although rare, breast tuberculosis can cause chronic infection, including the formation of abscesses and fistulas, leading to pus discharge from the nipple.
• Rare Diagnoses
  • Granulomatous Mastitis: A rare inflammatory condition of the breast that can mimic cancer or infection. It can cause nipple discharge and may be associated with systemic diseases.
  • Zuska-Atkinson Syndrome: A rare condition characterized by recurrent subareolar abscesses, often associated with ductal ectasia. It can cause chronic nipple discharge, including pus.