Differential Diagnosis for Erythematous Confluent Symmetrical Rash
- Single most likely diagnosis
- Contact Dermatitis: This is a common condition that can cause an itchy, erythematous rash, especially in areas that come into contact with irritants or allergens. The symmetrical distribution on the medial aspect of the thighs suggests a reaction to something that has come into contact with both thighs, such as clothing, soap, or other personal care products.
- Other Likely diagnoses
- Atopic Dermatitis (Eczema): This chronic condition can cause itchy, inflamed skin that can appear anywhere on the body, including the thighs. The symmetry and location of the rash could be consistent with atopic dermatitis, especially if the patient has a history of allergies or asthma.
- Seborrheic Dermatitis: This condition causes a red, itchy rash, typically on oily areas of the body. While it more commonly affects the scalp, face, and torso, it can also appear on the thighs, especially in the groin area.
- Intertrigo: This is a type of skin inflammation caused by friction and moisture in skin folds, such as the groin area. It can cause a red, itchy rash that is symmetrical and confluent.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stevens-Johnson Syndrome: Although rare, this severe skin condition can cause a rash that can appear anywhere on the body, including the thighs. It is usually accompanied by other symptoms such as fever, sore throat, and conjunctivitis, but early recognition is crucial as it can be life-threatening.
- Toxic Epidermal Necrolysis: Similar to Stevens-Johnson Syndrome, this is a severe skin condition that can cause widespread skin necrosis and detachment. It is usually triggered by medications and requires immediate medical attention.
- Rare diagnoses
- Erythema Nodosum: This condition causes red, painful nodules to appear on the skin, often on the shins, but can also appear on the thighs. It can be associated with various underlying conditions, including infections, autoimmune disorders, and medications.
- Granuloma Gluteale Infantum (or Adultorum): A rare condition characterized by reddish-brown nodules or plaques in the groin area, often associated with moisture and friction. It is more common in infants but can also occur in adults.