Table 1.
Summary of the clinical manifestations and histopathological features of SCAR syndromes.
| SCAR syndrome | Effector mechanisms | Clinical manifestations | Investigation findings | Histopathological features | Latency period | Common causal drugs |
|---|---|---|---|---|---|---|
| SJS/TEN | CD8+ cytotoxic T lymphocyte mediated Fas-FasL and granulysin-mediated apoptosis.4,8,155 | SJS and TEN are a disease continuum; the differentiation is based upon the percentage of body surface area of skin detachment.156–158 Acute onset of blisters and erosions affecting the skin, and mucous membranes; often associated severe systemic complications with significant morbidity and long-term sequelae.159 |
Abnormal liver, renal and respiratory function. Haematological, metabolic, fluid & electrolyte complications. | Subepidermal blister; spectrum of changes ranging from lichenoid reaction pattern with apoptotic keratinocytes, partial to full thickness epidermal necrosis.158 | 1–4 weeks.156,159 | Carbamazepine Phenytoin Lamotrigine Allopurinol Nevirapine NSAID* Sulfonamides Sulfasalazine159 |
| DRESS | T-cell mediated perforin-granzyme B as well as Fas/Fas L-dependent cell death.7,160 | Clinical presentation is heterogeneous: widespread exanthematous eruption, facial oedema, fever and lymphadenopathy.18,160,161
High variability in disease severity; some patients have modest systemic symptoms, while others develop significant morbidity due to internal involvement.160 |
Haematological abnormalities, most commonly eosinophilia and atypical lymphocytes. Abnormal liver, renal, respiratory and other organ function.18,160,161 |
Multiple histological patterns including: interface reaction, apoptotic keratinocytes, parakeratosis, spongiosis.161 | 2–6 weeks.79 | Carbamazepine Phenytoin Lamotrigine Allopurinol Sulfonamides Vancomycin Minocycline Amoxicillin79 |
| AGEP | Activation and proliferation of specific CD4 and CD8 T-cells, perforin/granzyme B and Fas ligand mechanisms to induce apoptosis.162 | Acute onset of widespread non-follicular sterile pustules overlying erythematous oedematous skin, starting in the intertriginous areas, often associated with fever.162–164 | Neutrophilia +/− eosinophilia, abnormal renal/liver function, hypocalcaemia.162–164 | Spongiform subcorneal and/or intradermal pustules with marked oedema of the papillary dermis and polymorphous perivascular infiltrate.165 | 1–5 days.163 | Amoxicillin Quinolones Sulfonamides Terbinafine Hydroxychloroquine Diltiazem166 |
AGEP: acute generalised exanthematous pustulosis, CD: cluster of differentiation, DRESS: drug rash with eosinophilia and systemic symptoms, NSAID: Non-steroidal anti-inflammatory drug, SJS: Stevens-Johnson syndrome, TEN: toxic epidermal necrolysis.