Pharmacology · single question
A patient developed a severe mucocutaneous reaction after taking a medication for a few days with widespread blistering. What is the diagnosis and hypersensitivity type?
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Correct answer: B. Stevens-Johnson Syndrome – Type IV
B) Stevens-Johnson Syndrome (SJS) – Type IV hypersensitivity — CORRECT.
SJS is a severe mucocutaneous drug reaction characterized by epidermal detachment, target lesions, oral erosions, and systemic involvement. It is classified as a Type IV (delayed/cell-mediated) hypersensitivity, involving cytotoxic T-lymphocyte-mediated destruction of keratinocytes. Common triggers: sulfonamides, anticonvulsants (carbamazepine, phenytoin), NSAIDs, allopurinol.
A) Erythema multiforme: Also Type IV but typically milder and often HSV-triggered — not the severe drug reaction described.
C) Type II: Cytotoxic — involves antibody-mediated cell destruction (not the mechanism of SJS).
D) Fixed drug eruption: Also Type IV but presents as a localized recurring patch at the same site.
SJS is a severe mucocutaneous drug reaction characterized by epidermal detachment, target lesions, oral erosions, and systemic involvement. It is classified as a Type IV (delayed/cell-mediated) hypersensitivity, involving cytotoxic T-lymphocyte-mediated destruction of keratinocytes. Common triggers: sulfonamides, anticonvulsants (carbamazepine, phenytoin), NSAIDs, allopurinol.
A) Erythema multiforme: Also Type IV but typically milder and often HSV-triggered — not the severe drug reaction described.
C) Type II: Cytotoxic — involves antibody-mediated cell destruction (not the mechanism of SJS).
D) Fixed drug eruption: Also Type IV but presents as a localized recurring patch at the same site.