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 common drugs =  NSAID's, tetracyclines, sulfa drugs, phenopthalein 
  
Clinical: 
| • | glans penis is most common site |  
 | • | usually develops within 30 minutes to 8 hours of drug administration |  
 | • | sometimes blister (subepidermal) |  
 | • | dusky in center because of necrosis |  
 | • | at the fixed drug site – will reproduce the lesion |  
 | • | another site – no reaction |  
   
  
distinctive variant:   
"Non-pigmenting Fixed Drug Eruption": 
| • | large, tender, often symmetrical erythematous plaques |  
 | • | "baboon syndrome" = where buttocks, groin, and axillae are preferentially involved  |  
   
  
  
histology: 
| • | dyskeratotic keratinocytes |  
 | • | ddx:  EM (histology = superficial), GVHD |  
 | • | confident distinction among fixed drug, EM, and TEN based on biopsy alone, is not always possible |  
   
  
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