Differential Diagnosis for Strep A Positive PCR, Exfoliating Rash, and Fever
Single Most Likely Diagnosis
- Scarlet Fever: This is the most likely diagnosis given the combination of a positive Strep A PCR (indicating a Group A streptococcal infection), an exfoliating rash, and fever. Scarlet fever is a disease resulting from a group A Streptococcus (group A strep) infection, the same bacteria that cause strep throat. It characteristically presents with a sandpapery rash, fever, and strawberry tongue.
Other Likely Diagnoses
- Strep Toxic Shock Syndrome (STSS): Although less common, STSS can present with fever, rash, and evidence of streptococcal infection. The rash may not always be exfoliating but can be part of a more severe systemic illness.
- Kawasaki Disease: This condition, primarily seen in children, involves fever, rash, and other systemic symptoms. While the rash is not typically exfoliating, the diagnosis should be considered, especially if other criteria like conjunctivitis, cervical lymphadenopathy, and changes to the lips and oral cavity are present.
Do Not Miss Diagnoses
- Toxic Epidermal Necrolysis (TEN): A severe skin condition usually triggered by medications, TEN can present with widespread skin exfoliation and fever. Although the primary cause is not infectious, missing this diagnosis could be fatal due to the high risk of sepsis and fluid loss.
- Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins, SSSS presents with fever, rash, and exfoliation. It's crucial to differentiate this from streptococcal infections due to different treatment approaches.
Rare Diagnoses
- Erythema Multiforme: A skin condition characterized by target lesions, it can sometimes present with fever and may rarely involve exfoliation. It's often associated with infections (including streptococcal) or medications.
- Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): A rare but severe drug reaction that can present with fever, rash, and systemic symptoms. Exfoliation may occur, and while it's not primarily an infectious disease, the presentation can mimic infections like scarlet fever.