Skin necrosis following local anesthetic: Same presentation for two different diagnoses

Area of Science:

• Dermatology
• Allergology
• Pharmacology

Background:

• Local anesthetics (LA) are common medications with generally good tolerance.
• Adverse reactions to LA frequently lead to allergy consultations.
• Most LA reactions are nonallergic, but rare allergic or pseudoallergic reactions occur.

Observation:

• Two patients presented with skin necrosis following local anesthesia with lidocaine.
• Patient 1 had necrosis attributed to the vasoconstrictive effects of epinephrine, exacerbated by vascular risk factors and substance use.
• Patient 2 was diagnosed with Nicolau syndrome (embolia cutis medicamentosa), a form of cutaneous necrosis at the injection site.

Findings:

• Skin necrosis following local anesthesia can stem from different mechanisms.
• Epinephrine's vasoconstrictive properties can precipitate necrosis in susceptible individuals.
• Nicolau syndrome represents a distinct embolic phenomenon causing skin necrosis post-injection.

Implications:

• Allergists must consider rare diagnoses in the differential diagnosis of local anesthetic hypersensitivity.
• Expanding the differential diagnosis improves patient outcomes for adverse LA reactions.
• Awareness of these rare presentations is crucial for accurate diagnosis and management.