Delayed Allergic Reactions to Jellyfish Stings: Usefulness of Ultrasonographic Evaluation.

Jellyfish stings often cause immediate local skin reactions, and, less frequently, the affected individuals may develop delayed allergic reactions days or months after the sting. Here, we present 4 such cases. In all cases, color Doppler ultrasonography was performed at the time of diagnosis, and in 3 of the cases, clinical follow-ups with ultrasonographic evaluations were performed. Ultrasonography initially showed dermal thickening with decreased echogenicity that progressively normalized during follow-up. Ultrasonography was useful in quantifying inflammation by measuring the thickness of the dermis and was more precise than standard clinical follow-up of cutaneous lesions in these cases.