DRESS Syndrome Diagnostic Criteria and Management

Core Diagnostic Features

DRESS syndrome typically presents after a latent period of 2-6 weeks following exposure to the offending drug, which distinguishes it from other drug reactions 1
The most common clinical manifestations include a morbilliform (maculopapular) confluent rash involving >30% of body surface area 1
Fever (>38°C) is a common symptom of DRESS syndrome 2
Internal organ involvement (liver, kidney, heart, lung) is a key feature of DRESS syndrome 1, 2

The RegiSCAR scoring system classifies DRESS syndrome cases as "no," "possible," "probable," or "definite" based on clinical and laboratory findings, including hematologic abnormalities such as eosinophilia (>700/μL or >10%) 1
Organ involvement, including liver (ALT >2 times upper limit of normal) and kidney (creatinine >1.5 times baseline) dysfunction, is a critical component of the RegiSCAR criteria 1, 2
The American College of Rheumatology recommends considering DRESS syndrome in the differential diagnosis of patients with fever, rash, and internal organ involvement 3

A complete blood count with differential is essential to assess for eosinophilia 2
Comprehensive metabolic panel to evaluate liver function (ALT, AST, alkaline phosphatase, bilirubin) and kidney function (BUN, creatinine) is crucial in diagnosing DRESS syndrome 1, 2
Additional testing, including urinalysis to evaluate for nephritis and blood cultures to rule out infectious causes, may be necessary 2

DRESS syndrome must be distinguished from other severe cutaneous adverse reactions, such as Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) 1
Systemic conditions, including viral infections and autoimmune disorders, should be considered in the differential diagnosis of DRESS syndrome 1

Certain genetic predispositions (HLA associations) are strongly linked to specific drug reactions, such as HLA-B*58:01 with allopurinol-induced DRESS 4, 1
The American Journal of Kidney Diseases recommends considering genetic predispositions when diagnosing and managing DRESS syndrome 4
Delayed diagnosis is common due to the variable presentation and latency period of 2-6 weeks after drug initiation, highlighting the need for prompt recognition and treatment 1

Constitutional symptoms including fever (>38°C), rigors, myalgias, and arthralgias are commonly present, as reported by the British Journal of Pharmacology 5
Other organ systems that may be involved include the kidneys (nephritis), lungs (pneumonitis), heart (myocarditis, pericarditis), and lymph nodes (lymphadenopathy), according to the British Journal of Pharmacology 5