DRESS syndrome overview
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# Overview
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome is a severe adverse drug reaction. The exact pathogenesis of DRESS syndrome is poorly understood, but it is thought that genetic deficiency of detoxifying enzymes, such as epoxide hydrolase deficiency, results in accumulation of toxic metabolites following drug administration and subsequent activation of immunologic reactions. The incidence of DRESS syndrome is approximately 10 to 100 per 100,000 drug exposures with a case-fatality rate of approximately 10%. DRESS syndrome has been reported among patients of all age groups with neither gender nor racial predilection. 
Common symptoms of DRESS syndrome include rash and fever. DRESS syndrome is characterized by a prolonged latency period (2-8 weeks following the administration of triggering drug). If left untreated, DRESS syndrome self-resolves following the discontinuation of the triggering drug in the majority of cases, but clinical manifestations may persist up to 3 months. Complications of DRESS syndrome include visceral organ involvement and development of chronic autoimmune diseases. Common physical examination findings of patients with DRESS syndrome include high-grade fever, diffuse exanthematous eruption (commonly exfoliative dermatitis), lymphadenopathy, facial edema, abdominal tenderness, and hepatomegaly. Laboratory findings of patients with DRESS syndrome usually differ depending on the organ involvement. Common Lab findings include anemia, eosinophilia, atypical lymphocytosis, monocytosis, thrombocytopenia, and elevated anti-HHV6 antibodies (viral reactivation). Drug withdrawal is the first step in the management of DRESS syndrome. Supportive care is considered the mainstay of therapy, and hospitalization and administration of pharmacologic agents is usually necessary. Medical therapy for the management of DRESS syndrome usually include topical and/or systemic corticosteroids, antipyretic agents, and symptomatic management of exfoliative dermatitis (fluids, nutritional support, management of electrolyte imbalances, and sepsis prevention).

# Historical Perspective
The early descriptions of DRESS syndrome were made in the 1940s and 1950s. The term DRESS syndrome was first coined by Helene Bocquet, a French dermatologist, in 1996.

# Classification
There is no classification system established for DRESS syndrome.

# Pathophysiology
The exact pathogenesis of DRESS syndrome is poorly understood. It is thought that an interaction between genetic and environmental factors is responsible for the development of DRESS syndrome. Genetic deficiency of detoxifying enzymes, such as epoxide hydrolase deficiency, results in accumulation of toxic metabolites and subsequent activation of immunologic reactions. A post-viral reaction (T-cell cross-reacion) has also been postulated due to the high incidence of viral reactivation following DRESS syndrome. On histopathological analysis of skin biopsy, DRESS syndrome is not characterized by a specific finding. Common histopathological findings include non-specific lymphocytic and eosinophilic infiltration with involvement of the papillary dermis and evidence of epidermotropism.

# Causes
DRESS syndrome is an adverse drug reaction. Common causes of DRESS syndrome include anticonvulsants, allopurinol, antiviral agents, and antibiotics, but virtually all drugs may cause DRESS syndrome.

# Differentiating DRESS syndrome from Other Diseases
DRESS syndrome must be differentiated from other diseases that cause fever, rash, and visceral involvement, such as exanthematous pustulosis, psoriasis, Still's disease, toxic epidermal necrolysis, Stevens-Johnson syndrome, lymphoma, serum sickness, drug-induced liver injury, and Staphylococcal scalded skin syndrome.

# Epidemiology and Demographics
The incidence of DRESS syndrome is approximately 10 to 100 per 100,000 drug exposures. The case-fatality rate of DRESS syndrome is approximately 10%. DRESS syndrome has been reported among patients of all ages with no gender or racial predilection.

# Risk Factors
There are no established risk factors in the development of DRESS syndrome. Possible risk factors in the development of DRESS syndrome include positive family history and rapid dose escalation of the triggering agent.

# Screening
Screening for DRESS syndrome in the general population is not recommended.

# Natural History, Complications and Prognosis
DRESS syndrome is characterized by a prolonged latency period (2-8 weeks following the administration of triggering drug). If left untreated, DRESS syndrome self-resolves following the discontinuation of the triggering drug in the majority of cases, but clinical manifestations may persist up to 3 months and the long-term sequelae have not yet been identified. Complications of DRESS syndrome include visceral organ involvement and long-term autoimmune diseases. The prognosis of DRESS syndrome is generally good, and the case-fatality rate is approximately 10%. Factors associated with worse prognosis have not yet been established.

# Diagnosis

## Diagnostic Criteria
There is no gold standard for the diagnosis of DRESS syndrome. Two diagnostic criteria have been proposed: The RegiSCAR criteria and the Japanese Consensus Group criteria.

## History and Symptoms
Common symptoms of DRESS syndrome rash and fever.

## Physical Examination
Common physical examination findings of patients with DRESS syndrome include high-grade fever, diffuse exanthematous eruption, lymphadenopathy, facial edema, abdominal tenderness, and hepatomegaly.

## Laboratory Findings
Laboratory findings of patients with DRESS syndrome usually differ depending on the organ involvement. Common Lab findings include anemia, eosinophilia, atypical lymphocytosis, monocytosis, and thrombocytopenia.

## Imaging Findings

## Other Diagnostic Studies
Other diagnostic studies for DRESS syndrome include elevated anti-HHV-6 antibody due to viral reactivation, positive lymphocyte activation test, patch testing, and possibly rechallenging of the suspected drug.

# Treatment

## Medical Therapy
Drug withdrawal is the first step in the management of DRESS syndrome. Supportive care is considered the mainstay of therapy, and hospitalization and administration of pharmacologic agents is usually necessary. Medical therapy for the management of DRESS syndrome usually include topical and/or systemic corticosteroids, antipyretic agents, and symptomatic management of exfoliative dermatitis (fluids, nutritional support, management of electrolyte imbalances, and sepsis prevention). Additional therapies have been attempted with variable success, including the use of N-acetylcysteine, intravenous immunoglobulins, and cyclosporin.

## Surgery

## Primary Prevention
There are no established measures for the primary prevention of DRESS syndrome. Primary prevention measures may include slow dose escalation of drugs (e.g. anticonvulsants), genetic counseling to patients with affected relatives, and in vitro impaired detoxification testing.

## Secondary Prevention
Secondary preventive measures to avoid DRESS syndrome include avoidance of drug re-exposure, screening for cross-reacting agents using in vitro lymphocyte toxicity assays, and possibly desensitization techniques.