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OVERVIEW
PART 1
PART 2
PART 3
PART 4
PART 5
PART 6
PART 7
Quiz
CHART CLUE
Across a lifetime, Stina collected five “separate” skinThe body’s largest organ, providing protection and regulation. diagnoses — guttate psoriasis, eczema, a sterile “fever rash,” mottled red legs, and slow-healing wounds. Each was treated as a local dermatology problem. Read together, they are one systemic, IL-1β/IL-6-driven autoinflammatory disease wearing the skin as its billboard.
The Story
For years, certain fevers came with a skin signature: tender, juicy red plaques that erupted as her temperature climbed and faded as it broke. One was finally biopsied. The pathologist’s report was almost a confession — a dense crowd of neutrophils packed into the dermisThe thick inner layer of the skin that contains blood vessels, nerves, and connective tissue., and not a single microbe. The note still read “atypical infection,” and another antibiotic was prescribed for a rash that had no germ in it at all.
That picture has a name — Sweet syndrome, an acute febrile neutrophilic dermatosis — and it is a textbook IL-1β event. Danger signals (not pathogens) activate the inflammasome inside neutrophils; the cytokines that follow make dermal blood vessels sticky, and neutrophils pour out of the circulation into the skin by diapedesis. The fever and the rash share one thermostat: the same IL-1β that resets the hypothalamusA small but vital brain region controlling hormones, temperature, and autonomic functions. (Module 1) is the signal calling neutrophils into the dermis. Stina’s “fever rash” is the case study’s whole thesis written in one biopsy.
From Stina’s chart: Recurrent during fevers: tender red plaques, biopsied once — “dense neutrophilic infiltrate, no organisms.” Read as “atypical infection.” It was Sweet syndrome.
Compare Stina’s uninfected appendixA small, finger-like pouch attached to the cecum, thought to play a role in immune function. to an infected appendix.
Activity:
Activity:
If inflamed vessels can fill the skin with neutrophils, what else can they do? Look at Stina’s legs — mottled, purple-netted, and red after a simple run — and the answer is written in the dermal circulationThe vascularization of the dermis of skin. Two capillary plexuses vascularize the dermis: subpapilla itself.
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The Barrier Breaking Down
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Red Feet & Mottled Shins
List of terms
- skin
- dermis
- hypothalamus
- appendix
- dermal circulation