Life-Threatening Skin Rashes (cont.)
Diagnosis of Life-Threatening Skin Rashes
Several of these disorders are difficult to diagnose in the emergency department. Blood tests, skin biopsies, and clinical presentation all play a factor in diagnosing each disorder. Doctors usually start treatment based on the symptoms and suspicion of one of these disorders and may not make a final diagnosis until after tests are done.
- A skin biopsy is taken using a special instrument designed to "punch out" a small round sample of skin.
- Biopsy specimens are taken out of either normal skin near the rash or in an area of redness that has not yet blistered.
- If skin biopsies are taken out of blistered areas, they are usually taken only from the skin forming the roof of the blister.
- Blood tests are sent for analysis to check for specific antibodies made by the body's natural immune system.
- Pemphigus vulgaris
- Skin biopsy samples of the blistering skin and normal appearing skin next to blistering areas are tested.
- Samples are stained to detect the antibodies that have attacked the proteins that hold together the outer layers of skin.
- Stevens-Johnson syndrome
- Diagnosis is usually made based on symptoms of the rash typical to SJS, mucous membrane involvement, and use of medications that have been known to cause this disease. A history of having taken medications associated with SJS is not essential for the diagnosis. A history of a recent viral infection can be helpful in making the diagnosis. In some individuals, however, no cause for the development of SJS is found, resulting in a number of patients for whom the cause is without an identifiable cause (termed idiopathic).
- Skin biopsy may also make diagnosis easier.
- Toxic epidermal necrolysis
- TEN is thought to be a more severe form of SJS.
- Diagnosis is made based on symptoms of a rash typical to TEN, mucous membrane involvement, and use of medications known to cause this disease. Like SJS a history of having taken medications associated with TEN is not essential for the diagnosis.
- Skin biopsy results show that the entire outer layer of skin has separated from the rest of the skin.
- Toxic shock syndrome
- Diagnosis of TSS is based on the following symptoms: fever greater than 102 F, a diffuse red rash, systolic blood pressure less than 90 or fainting upon standing, no evidence of other disease that may be causing the symptoms.
- A TSS diagnosis also requires the involvement of three or more other organ systems as evidenced by the following:
- Vomiting or diarrhea
- Muscle pain or blood test that shows enzyme levels consistent with breakdown of muscle
- Inflammation of the mouth, throat, vagina, or eyes
- Blood test showing evidence of kidney or liver dysfunction
- Disorientation or confusion
- Heart failure
- Respiratory failure
- Staphylococcal scalded skin syndrome
- Diagnosis is almost always made based on symptoms.
- Skin biopsy results are not always needed but, if performed, will show separation of the outer layer of skin.
Timothy J. Rupp, MD, FACEP, FAAEM
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