Differential Diagnosis for Itchy Rash

The patient presents with an itchy rash over the arms, antecubital neck, around the eyes, upper back, and around the lips, along with itchy eyes without redness, and has recently started on empagliflozin. The patient is also on atorvastatin, hydrochlorothiazide (hygroten), duloxetine, losartan, and tirzepatide. Here is a differential diagnosis organized into categories:

• Single Most Likely Diagnosis

  • Drug Rash (Empagliflozin-induced): Given the recent initiation of empagliflozin, a drug rash is a plausible explanation. Empagliflozin, like other medications, can cause skin reactions, including rash and itching. The timing of the rash in relation to starting the medication supports this diagnosis.

• Other Likely Diagnoses

  • Atopic Dermatitis (Eczema): The distribution of the rash (around eyes, neck, and lips) and the symptom of itchiness are consistent with atopic dermatitis. This condition is common and can be exacerbated by various factors, including stress and environmental changes.
  • Contact Dermatitis: This could be a consideration if the patient has been exposed to new soaps, detergents, or other products that come into contact with the skin. However, the distribution around the eyes and lips might be less typical for contact dermatitis unless the patient uses specific products in these areas.
  • Seborrheic Dermatitis: Although less likely given the description, seborrheic dermatitis can cause itchy rashes, particularly around the eyes and on the face. It's more commonly associated with a greasy, scaly appearance.

• Do Not Miss Diagnoses

  • Bullous Pemphigoid: An autoimmune blistering disease that can present with itchy skin lesions. Although less common, it's critical to consider due to its potential severity and the need for specific treatment.
  • Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN): These are severe skin reactions, often to medications, that can be life-threatening. The presence of itchy eyes without redness and a rash could be an early sign, although SJS/TEN typically involves mucous membranes and progresses rapidly.
  • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): A severe drug reaction that can cause rash, fever, and internal organ involvement. It's essential to consider this diagnosis given the patient's recent medication change.

• Rare Diagnoses

  • Pemphigus Vulgaris: An autoimmune disease causing blistering of the skin and mucous membranes. It's rare and typically presents with oral lesions first, but it could be considered in the differential for a rash with significant blistering components.
  • Cutaneous T-cell Lymphoma (Mycosis Fungoides): A rare type of skin cancer that can cause various skin lesions, including itchy rashes. It's less likely but should be considered if the rash is persistent and unresponsive to treatment.