Differential Diagnosis for a 34-year-old Female with SLE and Vesicular Rash

Single Most Likely Diagnosis

• Discoid Lupus Erythematosus (DLE): Given the patient's history of Systemic Lupus Erythematosus (SLE) and the presentation of a vesicular rash on the forehead extending to the upper eyelid, DLE is a strong consideration. DLE is a chronic skin condition characterized by inflammation and scarring type lesions, often found on sun-exposed areas, which aligns with the described location of the rash.

Other Likely Diagnoses

• Photosensitive Rash: Patients with SLE can experience photosensitive rashes, which are exacerbated by sunlight. The location on the forehead and upper eyelid, areas commonly exposed to sunlight, makes this a plausible diagnosis.
• Cutaneous Vasculitis: This condition involves inflammation of the blood vessels in the skin and can present with a variety of rashes, including vesicular ones. It is associated with several autoimmune diseases, including SLE.
• Bullous Lupus Erythematosus: A rare but distinct manifestation of SLE, characterized by the formation of bullae (blisters), which could initially appear as vesicles. This condition is autoimmune in nature and can be associated with SLE.

Do Not Miss Diagnoses

• Herpes Zoster (Shingles): Although less likely given the description, herpes zoster can present with a vesicular rash and is important not to miss due to the potential for serious complications, especially in immunocompromised patients like those with SLE. The rash typically follows a dermatomal distribution, but early stages might not clearly delineate this pattern.
• Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins, SSSS can present with widespread blistering and peeling of the skin, starting from the face. It's more common in children but can occur in adults, especially those with compromised immune systems.

Rare Diagnoses

• Pemphigus: An autoimmune disease characterized by blistering of the skin and mucous membranes. While it's rare, pemphigus can present with vesicles and bullae, and its autoimmune nature might link it to SLE, albeit very indirectly.
• Linear IgA Bullous Dermatosis: A rare autoimmune skin disorder characterized by blistering. It could be considered in the differential for a vesicular rash, especially if other diagnoses are ruled out and autoimmune markers are present.