Differential Diagnosis
- Single most likely diagnosis:
- Acute Exanthematous Pustulosis (AEP) or Acute Generalized Exanthematous Pustulosis (AGEP): This condition is characterized by the sudden onset of numerous small, sterile pustules on the skin, often accompanied by fever and neutrophilia. The patient's symptoms, including small blisters forming on the tips of her fingers, palms, soles, and interdigital areas, along with the recent initiation of amoxicillin, support this diagnosis. The improvement of her initial symptoms (sore throat, congestion, ear pain) followed by the development of skin lesions also fits the timeline for a drug reaction.
- Other Likely diagnoses:
- Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): Although less likely given the specific description of small blisters and the absence of explicit mention of eosinophilia or systemic symptoms beyond skin and neuropathic pain, DRESS syndrome is a consideration with drug exposures, especially with antibiotics like amoxicillin. It typically presents with a rash, fever, lymphadenopathy, and internal organ involvement.
- Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN): These are severe skin and mucous membrane disorders usually caused by an adverse reaction to medications, including antibiotics. The presence of skin lesions and mucosal involvement (lesions on her tongue) could suggest SJS/TEN, although the description does not fully align with the typical widespread skin detachment and mucosal involvement seen in these conditions.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Toxic Shock Syndrome: Although the patient's presentation does not strongly suggest toxic shock syndrome (TSS), it's a condition that can be fatal if not promptly recognized and treated. TSS can present with fever, rash, skin peeling, and multi-organ involvement, but it is typically associated with bacterial infections (e.g., Staphylococcus aureus or Streptococcus pyogenes) rather than a reaction to antibiotics.
- Vasculitis: Certain types of vasculitis, such as leukocytoclastic vasculitis, can present with skin lesions and systemic symptoms. While less likely, vasculitis can be severe and requires prompt diagnosis and treatment.
- Rare diagnoses:
- Erythema Multiforme: This is an immune-mediated skin condition characterized by target lesions. It can be triggered by infections or medications but is less likely given the patient's specific presentation.
- Pustular Psoriasis: Triggered by medications in some cases, pustular psoriasis presents with widespread pustules on the skin but usually has a different distribution pattern and is accompanied by other signs of psoriasis.