Lionfish sting is notable for its severe clinical presentation in the form of erythema, paresthesias, profound localized edema, and abdominal cramping. Systemic symptoms are rare. Fishermen, as well as swimmers and divers, are at an increased risk for a lionfish sting, with Central America being the main location where Lionfish reside. The diagnosis rests on clinical criteria and details obtained from patient's history.
The lionfish (Pterois volitans) belongs to the group of venomous Scorpaenidae and their natural habitat is restricted to the tropical regions of the world, primarily the Caribbean Sea and Central America . However, studies have confirmed their presence throughout the Atlantic Ocean, resulting in the increased risk for lionfish stings in South America and the United States, in addition to the Caribbean countries . Lionfish sting is considered to be a rare occurrence in clinical practice and activities that increase the risk include fishing, diving, or swimming in the mentioned areas  . Some reports have documented stings from lionfish kept in aquariums as well . The pathogenesis of a lionfish sting stems from the neurotoxic venom that is released by the fish during direct contact . Patients almost always present with symptoms involving a single extremity (upper much more commonly than lower)  , and most common signs are erythema and extensive edema accompanied by pain that is described as quite severe, whereas paresthesias, abdominal cramping, local heat, cyanosis, and blistering of the skin are frequent findings as well    . Cardiovascular symptoms, such as hypotension and tachycardia, are seen in a subset of patients, while hyperthermia, development of a localized infection, and transient weakness are less common findings    Although the clinical course typically ends with a good recovery without significant sequelae, limb paralysis, anaphylaxis, and heart failure have been reported   .
Because of the fact that lionfish stings are rather easily treated by immersing the affected extremity in hot water (due to the heat-labile properties of the neurotoxin)  , early recognition of this clinical entity can lead to prompt and effective therapy. For this reason, the physician's role in obtaining a detailed patient history is vital. Previous activities and confirmation of a lionfish sting by the patient is perhaps the most important piece of information needed to make the diagnosis. A full physical examination should follow, during which a complete inspection, as well as palpation of the affected extremity, must be carried out. At the time of admission, lionfish stings may present as erythema, blistering, or dermal necrosis  , depending on the duration of symptoms before the examination. Moreover, typical symptoms can be completely absent in the case of an "empty sting", ie. no venom was released from the lionfish . Although isolated reports document several abnormalities during biochemical workup in a small number of patients (hypophosphatemia, elevated liver enzymes, thrombocytopenia) , the diagnosis primarily rests on clinical criteria supported by findings revealed during history.