Differential Diagnosis for Dark Discolored Rash to Folds

• Single most likely diagnosis
  • Intertrigo: This is the most likely diagnosis due to the description of the rash being in the folds of the skin, which is a common location for intertrigo. Intertrigo is a type of skin inflammation caused by friction, moisture, and bacterial or fungal overgrowth in the skin folds.
• Other Likely diagnoses
  • Contact dermatitis: This could be a likely diagnosis if the rash is due to an allergic reaction or irritant in the skin folds.
  • Seborrheic dermatitis: Although it typically affects the scalp, face, and torso, seborrheic dermatitis can sometimes occur in skin folds, especially in the context of a more widespread eruption.
  • Eczema (atopic dermatitis): Eczema can sometimes present with dark discolored rashes, especially in skin folds, particularly in individuals with darker skin tones.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Necrotizing fasciitis: Although rare, this is a life-threatening condition that can start with a skin infection, including in skin folds. Early recognition is crucial for survival.
  • Cellulitis: A bacterial infection of the skin and subcutaneous tissues that can occur in skin folds and requires prompt antibiotic treatment to prevent serious complications.
• Rare diagnoses
  • Malignant acanthosis nigricans: A rare skin condition associated with internal malignancies, characterized by dark, velvety skin lesions, typically in the body folds.
  • Confluent and reticulated papillomatosis (CARP): A rare skin condition that can present with hyperpigmented papules in the skin folds, among other areas.