AGEP Validation Score: Differentiates drug eruptions from pustular psoriasis.
Diagnostic Criteria
Typical Pustules (Non-follicular)
Typical Erythema (Redness)
Rapid Evolution (<10 days)
Fever ≥ 38°C (100.4°F)
Neutrophils > 7000/μL
Awaiting Inputs
Select the clinical findings and laboratory markers to validate the probability of AGEP.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use
The EuroSCAR AGEP Validation Score is used to standardize the diagnosis of Acute Generalized Exanthematous Pustulosis (AGEP) and differentiate it from other severe pustular dermatoses, including pustular psoriasis, subcorneal pustular dermatosis, and other severe cutaneous adverse reactions (SCARs). It is applied to any patient presenting with an acute, generalized pustular eruption — particularly in the context of recent drug exposure.
Primary Indications
Acute onset of ≥ dozens of sterile non-follicular pustules on erythematous/edematous skin
Fever ≥ 38°C accompanying or preceding the pustular eruption
Recent drug exposure (most commonly aminopenicillins, macrolides, pristinamycin, diltiazem)
Peripheral blood neutrophilia (≥ 7 × 10⁹/L)
Rapid spontaneous resolution expected within 15 days of drug withdrawal
When NOT to Use
Known generalized pustular psoriasis without drug trigger (different pathophysiology)
Neonates and infants — clinical criteria differ significantly
When skin biopsy is unavailable (histology carries the highest discriminating weight)
As a drug causality tool — use ALDEN for per-drug attribution in confirmed AGEP
How it Works
Scoring Domain: Morphology
Pustules: Non-follicular, sterile, pinpoint size (+2 if typical; 0 if absent or atypical)
Erythema: Diffuse erythematous/edematous background (+1)
Distribution: Face and/or intertriginous/flexural predominance (+1)
Mucosal involvement: +0 (not scored positively; extensive mucositis favors SJS/TEN)
Scoring Domain: Course
Fever ≥ 38°C at onset or during eruption (+1)
Acute onset and resolution < 15 days after drug withdrawal (+1)
Postpustular desquamation (pinpoint scale following pustule resolution) (+1)
Scoring Domain: Laboratory & Histology
Neutrophilia (≥ 7 × 10⁹/L) (+1)
Histology: Subcorneal and/or intraepidermal spongiform pustules (+2 if both; +1 if one)
Histology: Papillary dermal edema (+1)
Histology: Vasculitis, eosinophils, or focal necrosis of keratinocytes (+1 each, max +1)
Score Interpretation
| ≤ 0 | Excluded — not AGEP |
| 1–4 | Possible AGEP |
| 5–7 | Probable AGEP |
| 8–12 | Definite AGEP |
Pathophysiology
AGEP is a T-cell–mediated hypersensitivity reaction. Drug-specific CD4+ and CD8+ T cells activate neutrophils via IL-8 (CXCL8) and GM-CSF, driving massive neutrophil emigration into the epidermis and forming the characteristic spongiform subcorneal pustules. Resolution follows drug elimination as the antigen-driven T cell response extinguishes. The process is distinct from the keratinocyte-targeted cytotoxicity of SJS/TEN.
Clinical Pearls
Clinical Pearls
AGEP onset is typically within 24–48 hours of drug initiation (especially aminopenicillins); delayed onset of 7–21 days is seen with other drug classes and may complicate attribution.
Resolution is brisk — persistent pustulation beyond 2–3 weeks after drug withdrawal should prompt re-evaluation for pustular psoriasis.
Pinpoint desquamation following pustule collapse is pathognomonic and helps confirm retrospective diagnosis.
Aminopenicillins, pristinamycin, and diltiazem are the highest-risk drugs per EuroSCAR multinational case-control data (n=97 AGEP cases vs. >900 controls).
AGEP rarely causes significant mucosal involvement — its presence in >2 sites should raise concern for SJS/TEN overlap or misdiagnosis.
Differentiating from DRESS and SJS/TEN
AGEP: Acute onset (hours–days), sterile pustules, neutrophilia, rapid resolution. DRESS: Delayed 2–8 weeks, morbilliform rash with eosinophilia, lymphadenopathy, organ involvement. SJS/TEN: Mucosal erosions, blistering, keratinocyte apoptosis on histology, higher mortality.
Limitations
Histological confirmation is required for the maximum discriminating score — biopsy may not always be performed emergently.
The score was designed for case validation in epidemiological studies; clinical use adapts it to individual patient decision-making.
Drug causality within a confirmed AGEP diagnosis requires a separate tool (ALDEN algorithm).
Next Steps
Excluded (≤ 0) or Possible (1–4)
01
Broaden differential: consider pustular psoriasis (personal/family history, IL-36 pathway mutations), subcorneal pustular dermatosis (Sneddon-Wilkinson), or folliculitis.
02
Do not reflexively discontinue all drugs — seek more specific diagnosis before attributing causality.
03
Obtain skin biopsy if not yet done; request DIF to exclude IgA-mediated pustuloses.
Probable (5–7) or Definite AGEP (8–12)
01
Immediately identify and discontinue the causative drug. Use ALDEN to score each drug for per-drug causality assessment.
02
Symptomatic management: topical corticosteroids for pruritus, emollients, antipyretics for fever.
03
Systemic corticosteroids are generally not required (self-limiting), though some centers use short courses for severe cases.
04
Monitor LFTs and renal function — rare systemic involvement (hepatitis, renal failure) has been reported.
05
Document in allergy records and alert patient: permanent avoidance of causative drug and pharmacologically related compounds.
06
Expected resolution within 15 days of drug withdrawal — if not resolving, reassess diagnosis.
The Evidence
Derivation & Validation Study
Acute generalized exanthematous pustulosis (AGEP) — a clinical reaction pattern.
Sidoroff A et al. • J Cutan Pathol.. 2001;28(3):113-9. Multinational EuroSCAR study; describes clinical features and presents the validation algorithm for AGEP case classification.
View SourceEuroSCAR Case-Control (Risk Factors)
Risk factors for acute generalized exanthematous pustulosis (AGEP)—results of a multinational case-control study (EuroSCAR).
Sidoroff A et al. • Br J Dermatol.. 2007;157(5):989-96. n=97 AGEP cases vs. 909 controls across 5 European countries; established drug-specific odds ratios and timing patterns.
View SourceExternal Links
Origins & History
The AGEP Validation Score was developed by the EuroSCAR (European Severe Cutaneous Adverse Reactions) study group, a multinational consortium funded by the European Commission. The 2001 paper by Dr. Alexis Sidoroff and co-authors (including Professor Jean-Claude Roujeau of Hôpital Henri Mondor, Créteil, France) formalized the clinical criteria and introduced a standardized validation algorithm for AGEP case classification. The score arose directly from the need for reproducible case ascertainment in the epidemiological study that preceded the 2007 EuroSCAR case-control study — the largest pharmacoepidemiological dataset on AGEP to date.
Prof. Jean-Claude Roujeau (1945–2022), Hôpital Henri Mondor / Université Paris-Est Créteil, was a co-author of the AGEP validation work and the leading international authority on severe cutaneous drug reactions for three decades. His contributions include SCORTEN, ALDEN, and seminal EuroSCAR datasets.
Last Comprehensive Review: 2026-07-17