Post-scabies Dermatitis Mimicking Treatment Failure: A Diagnostic Challenge.

Scabies is a common parasitic infestation caused by Sarcoptes scabiei var. hominis and is typically treated effectively with topical permethrin or oral ivermectin. After successful eradication, persistent pruritus and inflammatory skin lesions may still be present, leading to diagnostic uncertainty and unnecessary retreatment. We report a case of a 69-year-old male who developed persistent pruritic erythematous papules and eczematous plaques following appropriate permethrin and ivermectin therapy for confirmed scabies. Clinical reassessment and dermatology evaluation revealed no evidence of active infestation. The patient was diagnosed with post-scabies dermatitis, a hypersensitivity reaction to retained mite antigens. Treatment with topical corticosteroids, oral antihistamines, and emollients resulted in gradual symptom resolution over several weeks. This case highlights the importance of distinguishing post-scabies dermatitis from treatment failure or reinfestation to prevent unnecessary scabicide exposure and reduce patient anxiety regarding his unresolved condition.