A diagnostic red herring.

UNLABELLED: CLINICAL

INTRODUCTION

A 29-year-old keen parachutist presented to the emergency services in Cyprus complaining of sudden-onset facial flushing, dizziness and a widespread rash. The episode began on a hot day, 1 hour after she had eaten a breakfast of tinned tuna, and while she was ascending in an aircraft to parachute from 10 000 ft. She completed her jump uneventfully. She had no significant medical history (figure 1).emermed;35/3/184/F1F1F1Figure 1Patient's legs on presentation; this rash was generalised.

QUESTION: Based on the history and rash, which ONE of the following is the most likely diagnosis?Fish allergyHeat-related eruptionScombrotoxin poisoningStress-induced urticaria.