Differential diagnosis of fixed drug eruption and differentiating features
| Causes | Differentiating features |
|---|---|
| Insect bite | Erythematous papule with surrounding erythema or pruritic urticarial lesion |
| Bullous pemphigoid | Large fluid-filled blisters on flexor surfaces |
| Bullous fixed drug eruption | Well-demarcated solitary erythematous or violaceous circular patches |
| Erythema multiforme | Recurrent papular, bullous, necrotic lesions, often with central clearing |
| Leukocytoclastic vasculitis | Erythematous macules with palpable purpura |
| Lichen planus | Pruritic violaceous papules and plaques on wrists, lower back, ankles |
| Large plaque parapsoriasis | Oval erythematous or hyperpigmented macules and patches with fine scales and atrophy |
| Fixed drug eruption | Annular oval red or violaceus patch, often with pruritus; well defined and can be blistering or erosive Clinical presentation may vary based on subtype, including mucosal, nonpigmenting, targetoid, and bullous variants Presentation may be localized or generalized |
| Sarcoidosis | Painless, firm, oval nodules that are flesh-colored or violaceous |
Based on information from reference 2.