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Dermatology
Figurate Erythemas
Built from Dermatology, 5th Edition
What’s inside
6 sections · 151 slides
Overview
- What this topic covers
Figurate Erythemas: Overview and Classification
What a figurate configuration means, and the broad field of annular rashes it must be told apart from
- What is an erythema?
- The figurate shape
- The four classic figurate erythemas
- Other causes of annular rashes to keep in mind
- How the textbook organizes the wider differential
- Transient wheals: annular urticaria
- Reading the differential diagnosis table
- Differential diagnosis of figurate erythema
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Differential diagnosis of figurate erythema (continued)
- Eosinophilic annular erythema
Erythema Annulare Centrifugum
Rings that expand outward and clear centrally – often idiopathic, sometimes a clue to an underlying trigger
- Erythema annulare centrifugum: key features
- A name with a confusing history
- Why the name is still debated
- Who gets EAC
- EAC as a hypersensitivity reaction
- What can trigger EAC
- Blue cheese and other unusual triggers
- Clinical course: how a lesion grows
- Superficial vs. deep erythema annulare centrifugum
- Superficial and deep erythema annulare centrifugum
- What happens as EAC lesions resolve
- Superficial EAC pathology: the "coat sleeve" pattern
- Deep EAC pathology: why the border feels firm
- Telling EAC apart from urticaria
- Other conditions on the EAC differential list
- Treating EAC
- Second-line options, from case reports
Erythema Marginatum
A fleeting, migratory rash that is one of the diagnostic clues to acute rheumatic fever
- Erythema marginatum: key features
- Acute rheumatic fever: the underlying disease
- Diagnosing acute rheumatic fever (2015 criteria)
- Confirming the diagnosis
- A name over a century in the making
- ~3%
- Who gets erythema marginatum
- How strep triggers the rash: molecular mimicry
- How the rash behaves
- Erythema marginatum on the trunk
- Where the rash appears, and how long it lasts
- A subtler presentation
- Subcutaneous nodules and other rheumatic fever clues
- A look-alike rash in infants: annular erythema of infancy
- Erythema marginatum under the microscope
- Differential diagnosis of erythema marginatum
- Treating erythema marginatum
Erythema Migrans and Lyme Disease
The expanding "bull's-eye" rash that marks the start of a tick-borne infection
- Erythema migrans: key features
- Lyme disease: the underlying infection
- From tick bite to a named disease
- Where and when Lyme disease occurs
- ~30,000
- How the tick helps the infection take hold
- What happens once inside the body
- Different Borrelia species, different diseases
- The three clinical stages of Lyme disease
- Stages and major organ manifestations of Lyme disease
- What the classic rash looks like
- Classic erythema migrans with central clearing
- The rash does not always look textbook
- Multiple primary lesions from multiple bites
- Systemic symptoms alongside the rash
- When the infection spreads: disseminated erythema migrans
- Disseminated erythema migrans
- Disseminated disease can be widespread
- A closer look at scattered lesions
- Untreated Lyme disease: what can follow
- Ticks can carry more than one infection
- What erythema migrans looks like under the microscope
- Erythema migrans histology
- Making the diagnosis: the 2022 CDC case definition
- Abridged 2022 CDC Lyme disease surveillance case definition
- Laboratory testing: why blood tests can mislead early on
- Culture and PCR: more specific, less practical
- Differential diagnosis of erythema migrans
- A closer look at the bite site
- Treating erythema migrans
- Treatment options for Lyme disease
- Treatment options for Lyme disease (continued)
- Treating disease beyond the skin
- Treatment of extracutaneous manifestations of Lyme disease
- Reactions to starting treatment
- Should every tick bite be treated?
- Single-dose prophylaxis after a high-risk tick bite
Erythema Gyratum Repens
A rare, fast-moving figurate rash that is almost always a marker of an internal cancer
- Erythema gyratum repens: key features
- History and how rare it is
- How a tumor produces a skin rash
- Supporting evidence, and what is still unclear
- The wood-grain rash
- The wood-grain pattern of erythema gyratum repens
- ≥70%
- What else can trigger a similar rash
- Erythema gyratum repens under the microscope
- Differential diagnosis of erythema gyratum repens
- A key mimic: resolving pityriasis rubra pilaris
- Treating erythema gyratum repens
- The four classic figurate erythemas, side by side
- A practical approach to a figurate rash
- Key takeaways
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Dermatology, 5th Edition (2-Volume Set)