Differential Diagnosis for Widespread Vesicular Rash
Single Most Likely Diagnosis
- Varicella (Chickenpox): This is the most likely diagnosis due to the description of a widespread vesicular rash that is pruritic, affecting the trunk and face. Varicella typically presents with a prodrome of fever and malaise, followed by the characteristic rash.
Other Likely Diagnoses
- Herpes Zoster (Shingles): Although it usually presents in a dermatomal distribution, in immunocompromised patients, it can disseminate and appear similar to varicella. The rash is also vesicular and pruritic.
- Eczema Herpeticum: A disseminated herpes simplex infection in patients with atopic dermatitis, presenting with widespread vesicular rash, although it's more common in areas of pre-existing eczema.
- Pemphigus Vulgaris: An autoimmune disease that can present with widespread vesicles and bullae, although it's less common and usually involves mucous membranes.
Do Not Miss Diagnoses
- Primary Herpes Simplex Virus (HSV) Infection: Although less common, a primary HSV infection can present with a widespread vesicular rash, especially in immunocompromised patients. Missing this diagnosis could lead to severe complications.
- Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins, SSSS can present with a rash that progresses to widespread blistering and peeling, which can be life-threatening, especially in children.
Rare Diagnoses
- Bullous Pemphigoid: An autoimmune disease characterized by the presence of bullae, which can be widespread but is less common and typically affects older adults.
- Drug-Induced Linear IgA Disease: A rare condition caused by certain medications, presenting with a vesicular rash, which can be widespread and may mimic other conditions.
- Acute Generalized Exanthematous Pustulosis (AGEP): A rare skin condition usually triggered by medications, characterized by numerous small, sterile pustules on a background of erythema, which can be mistaken for a vesicular rash.