Differential Diagnosis for Under Breast Rash

• Single most likely diagnosis
  • Intertrigo: This is the most likely diagnosis due to the warm, moist environment under the breast, which is prone to friction and fungal or bacterial overgrowth, leading to intertrigo.
• Other Likely diagnoses
  • Eczema (atopic dermatitis): Can occur in skin folds, including under the breast, due to irritation or allergic reactions.
  • Contact dermatitis: Irritation from clothing, soaps, or other substances can cause a rash under the breast.
  • Candidiasis: A fungal infection that thrives in warm, moist areas, making the under-breast area a common site.
  • Seborrheic dermatitis: Can occur in oily areas of the body, including under the breast, especially if there's a history of similar rashes on the scalp or face.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Inflammatory breast cancer: Although rare, it can present with skin changes, including a rash under the breast, and is critical to diagnose early.
  • Cellulitis: A bacterial infection of the skin that can spread rapidly and become serious if not treated promptly.
  • Abscess: A collection of pus that can form under the breast, requiring drainage and antibiotic treatment.
• Rare diagnoses
  • Granulomatous lobular mastitis: A rare inflammatory condition of the breast that can cause skin changes and rashes.
  • Sarcoidosis: A systemic disease that can cause skin lesions, including under the breast, though this is less common.
  • Psoriasis: While more commonly found on elbows, knees, and scalp, psoriasis can occasionally occur in skin folds, including under the breast.