Differential Diagnosis
- Single most likely diagnosis
- Guttate Psoriasis: This condition is characterized by the sudden onset of small, red, scaly lesions, often triggered by a streptococcal infection, which fits the patient's history of recent sore throat and positive throat culture for Streptococcus. The drop-like appearance of the plaques is also typical for guttate psoriasis.
- Other Likely diagnoses
- Pityriasis Rosea: Although the trigger is often unknown, the presentation of small, red, scaly lesions, particularly with a herald patch, could be considered. However, the direct link to a streptococcal infection and the specific description of drop-like plaques makes this less likely.
- Secondary Syphilis: This condition can present with a wide range of skin manifestations, including small, red, scaly lesions. However, it would typically be accompanied by other systemic symptoms and a history that might suggest exposure.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningococcemia: Although rare and not directly suggested by the skin lesions alone, any condition that presents with a sudden onset of a rash, especially in the context of a recent infection, should prompt consideration of meningococcemia due to its high mortality rate if not promptly treated.
- Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis: These are severe skin conditions usually triggered by medications or infections. While the presentation might not exactly match, any widespread skin condition with a potential for severe consequences should be considered, especially if there's a suspicion of a drug or infectious trigger.
- Rare diagnoses
- Kawasaki Disease: Typically seen in children, it could be considered in young adults with a rash and recent infection, though other criteria such as fever, lymphadenopathy, and desquamation in the hands and feet would need to be present.
- Erythema Multiforme: This condition can present with target lesions and is often associated with infections (including streptococcal) or medications. While it's a possibility, the description provided leans more towards guttate psoriasis.