Differential Diagnosis for Rash Under Arms from Skin Rubbing

• Single Most Likely Diagnosis
  • Intertrigo: This is the most likely diagnosis due to the location of the rash (under the arms) and the cause (skin rubbing). Intertrigo is a type of skin inflammation caused by friction, moisture, and bacterial or fungal overgrowth in warm, occluded areas of the body.
• Other Likely Diagnoses
  • Contact Dermatitis: This could be due to an allergic reaction or irritant from clothing, soaps, or other products that come into contact with the skin under the arms.
  • Eczema (Atopic Dermatitis): Individuals with atopic dermatitis may experience exacerbations in areas subject to friction, such as the axillary region.
  • Folliculitis: An inflammation of the hair follicles, which can be caused by friction, among other factors, and is common in areas like the axillae.
• Do Not Miss Diagnoses
  • Inverse Psoriasis: Although less common, inverse psoriasis can present in skin folds, including the axillae, and is characterized by smooth, red patches. Missing this diagnosis could lead to inappropriate treatment and significant discomfort.
  • Tinea Cruris (Jock Itch): A fungal infection that can spread to the axillary region, especially in individuals with poor hygiene or who are prone to excessive sweating.
• Rare Diagnoses
  • Hailey-Hailey Disease (Familial Benign Pemphigus): A rare genetic disorder that causes blisters and erosions in the skin folds, including the axillae, due to friction and minor trauma.
  • Darier Disease: A rare genetic disorder that affects the skin and sometimes presents with lesions in the axillary region, among other areas.