SEARCH RESULTS FOR: Scarlet-Fever

Scarlet Fever

Scarlet Fever: Pathogenesis and clinical findings Exotoxins enter systemic circulation Exotoxins act as superantigens which do not require specific antigen recognition & simultaneously bind Major Histocompatibility Complex (MHC) class II molecules & T cell receptors Non-specific nature of the T cell activation results in mass T cell activation T-cells trigger release of pro- inflammatory cytokines like tumor necrosis factor (TNF), interleukins, & interferons Leukocytes, desquamated epithelial cells, & inflammatory exudate accumulate in the orophayrnx A white membrane forms on the tongue with enlarged protruding papillae The membrane sloughs off in 2-3 days Immune cells trigger vasodilation Inflammation causes hyperemia & edema of denuded tongue & lingual papillae Group A Streptococci infect the host (most commonly 5-15 years of age) Group A Streptococci release streptococcal pyrogenic exotoxins In addition to molecular mimicry, superantigen can cause selective expansion T cells in skin lesions leading to keratinocyte activation & characteristic psoriatic lesions Guttate Psoriasis Leads to systemic inflammatory damage Toxic Shock Syndrome White strawberry tongue Red strawberry tongue Previously exposed patients develop a delayed hypersensitivity response to the toxins Immune cells rapidly release cytokines & recruit leukocytes ↑ Vascular permeability, vascular dilation, & perivascular leukocyte infiltration leads to dermal edema Papules cluster linearly in skin folds such as antecubital fossae, neck, & groin An erythematous maculopapular, blanchable & non-painful rash appears where skin is most sensitive Reduced immune pathway activity & sympathetic vasoconstrictor input in the face, palms, & soles limit rash development in these areas 7-10 days post-pharyngitis Rash fades & skin desquamates Pastia’s lines Scarlatiniform rash (sandpaper- like rash) on the upper trunk, axillae & groin Circumoral pallor Exotoxins stimulate mononuclear cells which cause direct cell injury & death & release leukocytes & tumor necrosis factor (TNF) in the pharynx Endothelial modulators are released ↑ Gap between endothelial cells & fluid & proteins leak from vessels into interstitial space Pharyngitis** Authors: Kayla Huggard Reviewers: Alua Kulenova Danielle Nelson* * MD at time of publication **see corresponding Calgary Guide slide Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Aug 16, 2026 on www.thecalgaryguide.com Creative Commons