What are the diagnosis criteria for DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) syndrome?

From the Guidelines

DRESS syndrome is diagnosed using a combination of clinical and laboratory criteria, including fever, enlarged lymph nodes, internal organ involvement, blood abnormalities, and widespread skin rash, with a temporal relationship between drug exposure and symptom onset, as outlined in the RegiSCAR scoring system 1. The diagnosis of DRESS syndrome requires a thorough evaluation, including:

• A total body skin examination with attention to examining all mucous membranes, as well as a complete review of systems 1
• Ruling out other etiologies of the skin problem, such as infection, another drug effect, or a skin condition linked to another systemic disease 1
• A biologic checkup including a CBC with DIFF, liver, and kidney function tests; consider UA in the context of DRESS to assess for associated nephritis in addition to the blood work 1
• Skin biopsies to assess for full-thickness epidermal necrosis, as is seen in SJS or TEN, as well as other possible etiologies like paraneoplastic pemphigus or other autoimmune blistering dermatoses or other drug reactions, such as AGEP 1 The most recent and highest quality study, published in 2021 in the Journal of Clinical Oncology, provides guidance on the management of immune-related adverse events, including DRESS syndrome 1. Key points to consider in the diagnosis and management of DRESS syndrome include:
• The presence of at least three of the following criteria: fever above 38.5°C, enlarged lymph nodes in at least two sites, involvement of at least one internal organ, blood abnormalities, and widespread skin rash covering more than 50% of the body
• The exclusion of other potential causes and the establishment of a temporal relationship between drug exposure and symptom onset, typically 2-6 weeks after starting the medication
• The importance of prompt withdrawal of the offending drug and the use of supportive care, including topical emollients, oral antihistamines, and high-strength topical corticosteroids, as well as IV methylprednisolone in severe cases 1
• The consideration of alternative treatments, such as IVIG or cyclosporine, in severe or steroid-unresponsive cases 1

From the Research

Diagnosis Criteria for DRESS Syndrome

The diagnosis of DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) syndrome is based on a combination of clinical, laboratory, and histopathological findings. The key criteria for diagnosing DRESS syndrome include:

• Fever
• Cutaneous eruption (skin rash)
• Eosinophilia (elevated eosinophil count)
• Atypical circulating lymphocytes
• Lymphadenopathy (enlarged lymph nodes)
• Hepatitis (liver involvement) At least three of these findings must be present to diagnose DRESS syndrome 2, 3.

RegiSCAR Scoring System

The RegiSCAR scoring system is used to classify DRESS cases as "no," "possible," "probable," or "definite" based on the presence and severity of these criteria 2, 4. This system helps to standardize the diagnosis of DRESS syndrome and ensures that cases are consistently classified.

Clinical Presentation

DRESS syndrome can present with a range of symptoms, including:

• Extensive rash
• Fever
• Lymphadenopathy
• Hematologic abnormalities (eosinophilia and/or atypical lymphocytosis)
• Internal organ involvement (e.g., liver, kidneys) 4, 5 The clinical presentation of DRESS syndrome can vary widely, making diagnosis challenging.

Laboratory Findings

Laboratory tests can help support the diagnosis of DRESS syndrome, including:

• Elevated eosinophil count
• Atypical circulating lymphocytes
• Elevated liver enzymes (e.g., transaminases)
• Abnormal blood smear findings (e.g., schistocytes) 6, 3 These laboratory findings can help confirm the diagnosis of DRESS syndrome and monitor the patient's response to treatment.

Histopathology

Histopathological examination of skin biopsy specimens can also support the diagnosis of DRESS syndrome, showing features such as:

• Perivascular infiltrate
• Eosinophilic infiltration
• Keratinocyte necrosis 3 Histopathology can help confirm the diagnosis of DRESS syndrome and distinguish it from other skin conditions.