Background
A 34-year-old otherwise healthy man presents to the emergency department (ED) with a pruritic rash on the lower-left part of his chest. The patient states that he experienced swelling and pain at the same site 5 days before presentation but that those symptoms have since disappeared. He denies having any rashes elsewhere on his body, any exposure to new medications or foods, any recent insect bites, or any use of new soaps or lotions. The patient recently returned from a vacation to a tropical region, where he had gone snorkeling; however, he cannot immediately recall any unusual exposures or injuries during that time. He denies having any fevers, wheezing, difficulty breathing, nausea, or upper respiratory symptoms.
{mosimage}The patient has normal vital signs, and the physical findings are only remarkable for 2 distinctly linear, erythematous, and vesiculopapular rashes on the left lower aspect of the chest wall (see Image).
What is the diagnosis?
Hint
The patient recalls brushing up against something while snorkeling during his vacation.
Authors:
Allison Richard, MD, Attending Physician, Assistant Professor of Emergency Medicine, Department of Emergency Medicine, LAC/USC Medical Center
Mathew Richard, MD, Attending Physician, Department of Emergency Medicine, Antelope Valley Medical Center, Lancaster, CA
eMedicine Editors:
Erik D. Schraga, MD, Department of Emergency Medicine, Kaiser Permanente, Santa Clara Medical Center, CA
Rick G. Kulkarni, MD, FACEP, Assistant Professor, Yale School of Medicine, Section of Emergency Medicine, Department of Surgery, Attending Physician, Medical Director, Department of Emergency Services, Yale-New Haven Hospital, CT
Answer
Type IV delayed hypersensitivity reaction to fire coral: During the detailed history taking, the patient describes brushing up against an orange coral with his left torso. He had an immediate burning sensation and urticarial rash, which disappeared the next day; however, 5 days later, a pruritic vesiculopapular rash appeared in the same location (see Image).
Fire corals, which belong to the phylum Cnidaria (which includes aquatic invertebrate animals such as the Portuguese man-of-war, jellyfish, and sea anemones), are found throughout the world’s coral reefs (except in Hawaii), generally in shallow water. This group of hydrocorals possess nematocysts, which are stinging cells that, with a harpoon-like action, become embedded in the dermis and envenomate the victim.
The venom released from the nematocyst causes contact dermatitis characterized by an immediate but typically transient stinging sensation that ranges from mild to severe in intensity. Severe pruritus, vesiculation, urticaria, and necrosis are uncommon. Delayed contact hypersensitivity reactions may persist for days or, in rare cases, months. The rash is usually self-limited, and it is initially treated with the application of ice packs and analgesics. If recognized immediately after exposure, the site may be rinsed with ambient seawater followed by application of vinegar to prevent further nematocyst envenomation. To treat the delayed hypersensitivity rash or local pruritus, topical steroids are beneficial. Oral corticosteroids may be indicated to manage diffuse, severe, or persistent disease.
Type IV hypersensitivity reactions are cell-mediated inflammatory reactions that typically occur 48-72 hours after exposure to an antigen. Initiation of this type of reaction is by monocytes/macrophages and basophils. Infiltration by cytotoxic T-cells and macrophages results in granuloma formation.
Delayed hypersensitivity reactions play an important role in a host’s defense against intracellular pathogens. Important examples include tuberculin skin reactions, in which individuals previously exposed to tuberculosis develop a reaction in the exposed area in 48-72 hours; Jones-Mote hypersensitivity, which is characterized by a host response to a pure protein mixed with an adjuvant; graft versus host disease, in which the body rejects a graft in a similar manner as it responds to a tuberculin antigen; and contact hypersensitivity (eg, that caused by poison ivy or fire coral), which occurs when an antigen comes in contact with skin. This hypersensitivity is characterized by a largely basophilic infiltrate and eczematous- or vesicular-appearing rashes, peaking 3-6 days after exposure.
Other types of hypersensitivity reactions include type I, which is an immediate and immunoglobulin E (IgE)–mediated histamine release, such as that occurring after a bee sting; type II, which is an antibody- and complement-related cytotoxicity, such as Goodpasture syndrome; and type III, which is mediated by circulating antigen-antibody complexes, such as those observed in serum sickness.
References:
Dagregorio G, Guillet G. Delayed dermal hypersensitivity reaction to coral. J Am Acad Dermatol 2005 Mar;52(3 pt 1):534-5. [MEDLINE: 15761443]
Hinshaw WD, Neyman GP, Olmstead SM. Hypersensitivity Reactions, Delayed. eMedicine Journal [serial online]. Last updated: 2005. Available at: http://www.emedicine.com/med/topic1100.htm.
Miracco C, Lalinga AV, Sbano P, Rubegni P, Romano C.. Delayed skin reaction to Red Sea coral injury showing superficial granulomas and atypical CD30+ lymphocytes: report of a case. Br J Dermatol 2001 Nov;145(5):849-51. [MEDLINE: 11736921]
Paradisi M, Grassi A, Conti G, et al: Fire coral persistent cutaneous reaction [case report]. Acta Dermatovenerol Alpine Pannonica Adriat [serial online] . Last updated: 2001. Available at: http://www.mf.uni-lj.si/acta-apa/acta-apa-01-1/4-clanek.html.
