Life-Threatening Skin Rashes (cont.)
What Tests Do Doctors Use to Diagnose 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.
- Toxic epidermal necrolysis
- Diagnosis is usually made based on symptoms of the rash typical to TEN, 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 TEN 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.
- TEN is thought to be a more severe form of SJS.
- Diagnosis is made based on signs and 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, and 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
- Diagnosis is based on clinical findings and the identification of the organism from the blood or spinal fluid in a severely ill patient. The diagnosis must be suspected early and appropriate antibiotic therapy instituted before systemic organ failure becomes irreversible. In modern medical centers, the fatality rate is 10%-14%.
- Rocky Mountain spotted fever
- The diagnosis is based on the clinical picture in a patient with a documented or suspected tick bite. Although identification of the organism is very important, treatment should be instituted early to avoid severe postinfection effects, as well as death. The disease is usually confirmed by a blood test.
- Necrotizing fasciitis
- The diagnosis is suspected in a patient with acute onset of a severe febrile illness associated with an extremely painful infected extremity. X-rays examination of the affected extremity may be helpful. Diagnosis is confirmed by growing the bacteria isolated from the infected site or from the blood.
Medically Reviewed by a Doctor on 5/20/2016
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