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Dermatology Pathology > Urticaria and Drugs Rashes > Flashcards

Urticaria and Drugs Rashes Flashcards

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Dermatology Board Prep flashcards
1
Q

What are hives?
• what causes them?

A

Remember hives are evanescent, itchy swellings of skin caused by an inflammatory reaction in skin mediated by release of histamine and other cytokines into the skin. This causes capillary leakage and swelling into the DERMIS causing edema.

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2
Q

Are hives typically allergic or non-allergic?
• what are your chances of getting them?

A

about 1/2 of the cases of urticaria are non-allergic in nature
• prevanlance of getting hives is about 1/5

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3
Q

What are the key features seen here?

A

These are hives, there is no scale (not tinea) and its not indurated.
• these may come and go into different places

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4
Q

How long do urticaria last?
• how long does angioedema last?

A

Uriticaia last a few hours before resolving but you may get a series of lesions over a longer period of time.

Angionedema lasts up to 72 hours

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5
Q

What defines acute vs. chronic urticaria?
• what is the most common cause of both?

A

Acute are less than 6 weeks in duration

Chronic are more than 6 weeks in duration

***The most common cause of each of these is ideopathic***

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6
Q

What are some reasons to get acute urticaria?

A
  • Infections (40% - 2nd most common cause)
  • Drugs: ß-lactam antibiotic, NSAIDs, Asprin, opiates, contrast media
  • Food: eggs, peanuts, soy, shellfish
  • Inhalants
  • Stress
  • Systemic diseases
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7
Q

What are some causes of Chronic Urticaria?

A

1 ideopathic

• Chronic Infections
• Rheumatologic Disorders
• Autoantibodies to IgE receptor or mast cells

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8
Q

When are you most likely to see angioedema in conjuction with urticaria?
• how often does angioedema occur in adults with urticaria?

A

40% of cases of urticaria in adults presents with angioedema most often this is associated with FOOD-INDUCED urticaria

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9
Q

What are two potential reasons you would see angioedema without uriticaria?

A

GENETIC
C1 inhibitor deficiency or dysfunction
**Note this is accompanied by abdominal pain often times**

DRUG INDUCED
ACE inhibitor induced

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10
Q

Where besides the lips can angioedema occur?

A

• Tongue, larynx, respiratory tract
• Periorbital area
• Hands and Feet
• GI tract

**If this gets bad enough you might get signs of anaphylactic reaction**

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11
Q

What are some forms of Urticaria that have a physical cause?

A
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12
Q

How do you treat Urticaria?
• Angioedema?
• Anaphylaxis?

***What drugs should you avoid?***

A

Urticaria
• treat with antihistamines, leukotriene anatagonists, H2-blockers
• Avoid systemic steroids due to risk of rebound

Angioedema and Anaphylaxis are treated with Epinephrine

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13
Q

What possibility should you consider if any Urticarial plaque lasts more than 24 hours without migrating?
• what would you do to confirm or rule out a dx?

A

VASCULTITIS - Do a biopsy to determine Dx

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14
Q

Who is at an increased risk for Cutaneous drug reactions?
• what drugs are commonly to blame?

A

Increased Risk:
• 1OLD (increasing age), 2WOMEN, with 3CONCOMITANT VIRAL INFECTIONS (HIV, EBV, ect)

Common offenders:
• Antibiotics
• Anticonvulsants
• NSAIDs

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15
Q

How does the clinical presentation of a cutaneous drug reaction differ from your typical urticarial rash from a typical allergin?
• what more serious rashes do drugs sometimes cause?

A

90% of drugs reactions result in the formation of a morbilliform rash and only 5% are urticarial.

Drugs may also cause:
•

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16
Q

What is different about a morbilliform rash from typical urticaria?

A

• Morbilliform rash typically consists of many red/pink ITCHY papules that are fixed in a single location (where as urticaria seem to move). These often merge together to make one big rash (become more confluent).

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17
Q

Is this likely drug related? or is is most likely shellfish?

A

Drug related, its a flat rash made of lots of macula

18
Q

Where do Morbilliform drug eruptions typically occur?
• what if your patient is thrombocytopenic?

A

Morbilliform drug eruptions typically occur in dependent-pressure bearing areas.
If your patient is thrombocytopenic then you may get purpura in dependent areas.

19
Q

How does a morbilliform drug rash typically present?
• how long until it resolves?

A

Morbilliform drug rashes typically start 5 to 7 days after starting a drug and can occur even a few days after the drug is discontinued. Most often the rash resolves spontaneously in one to two weeks without complications .

20
Q

How does the cause of this rash differ from one that causes urticaria?

A

Morbilliform drug rashes are type IV hypersenitivity reactions (T-cell mediated) in contrast urticarial reactions are type I hypesenstivity (IgE mediated)

21
Q

What drugs are most often responsible for Morbilliform drug reactions?

A

• Penicillins
• Cephalosporins
• Sulfonamides
• Anticonvulsants

22
Q

What is this?
• How long did this take to occur?

A

Urticarial Drug Reaction - second most common type of drug reaction
• occurs within minutes of exposure

23
Q

How long does it take hives from a urticarial drug reaction to resolve?
• compare this to morbilliform drug reactions ?
• what is the most common culprit of an urticarial drug reactions?

A

Hives from urticarial reactions typically resolve in hours compared to a week or two with morbilliform reactions.

Most common causes;
• Penicillins
• Cephalosporins
• Asprin
• Latex

24
Q

Is this a urticarial or morbilliform drug reaction?
• what prerequisite is needed to have this type of reaction?

A

This is a URTICARIAL drug rash with a random geographic patten. This is an IgE mediated response so prior exposure is required to develop the hypersensitivity.

25
Q

DRESS syndrome:
• aka?
• How does it present

A

aka drug hypersensitivity syndrome.

Patient presents with a systemically ill appearance with a severe morbilliform rash and eosinophilia 2-6 WEEKS after starting a drug. Other physical findings might includ fever, LAD, and joint pain.

26
Q

DRESS syndrome
• what organ system is often involved?
• how long does this persist?

A

LIVER is often involved in DRESS syndrome so look for elevated LFTs. This reaction often persists for WEEKS to MONTHs after the drug is stopped.

27
Q

How does dress syndrome compare to a normal drug reaction?

A

Dress syndrome continues much long after discontinuing the drug.

28
Q

How do you treat DRESS syndrome?
• what drugs are common culprits?

A

Dress Syndrome requires LONG-TERM corticosteriod treatment.

Commonly Implicated:
• Anticonvulsants
• Antibiotics: Sulfonamides, minocycline, erythromycin

29
Q

Someone presents with DRESS syndrome and angioedema.
• how should you treat them?
• What are they likely to die of?

A

Angioedema is an indicator that you need to give them EPINEPHRINE (i think).

• 10% of people with DRESS die of fluminant hepatitis

30
Q

What is a this?
• key characteristics?

A

Fixed Drug eruption
KEYS:
• well circumscribed red/brown plaque

31
Q

Fixed Drug Eruption - Presentation?
• does this heal?
• What happens if you take the same drug again?
• WHERE are you likely to see it?

A

Well circumscribed red/brown fixed drug eruptions that may appear with blistering and often heal with hyperpigmentation and often occur on the genitals, lips, and extremities.
• these often occur in response to a medicine that you take infrequently causing them to recur somewhat sporadically.

32
Q

What are some common causes of this?

A

Sulfonamides
NSAIDS
Laxitives

33
Q

Stephen-Johnson Syndrome/ Toxic epidermal necrolysis
• what is this? KEY AREAS of tissure involvment?
• Etiology?

A

SJS/TEN:
• Spectrum of the same disease that leads to life threatening blistering of the skin and drugs are often implicated but the exact etiology is unclear. MUCOUS MEMBRANE involvment is a key finding. MUCOUS MEMBRANE INVOLVEMENT IS HALLMARK

34
Q

How do you distinguish between TEN and SJS?

A

Only difference is the amount of Surface area involved. SJS is less than 10%. TEN is more than 15%. Mixed is between 10 and 15%.

35
Q

Compare and contrast the time needed until onset of the following:
• Morbilliform Drug Rash
• Urticarial Drug Reactions
• DRESS
• SJS/TEN

A

The earliest occuring syndrome is urticaria with may arise within minutes of exposure (or a week later if there has never been an initial exposure). The next to occur would be a Morbilliform drug rash that would occur 5-7 days after starting the drug. DRESS syndrome often arses 2-6 weeks after exposure. SJS and TEN occur 1-2 months after starting a drug.

36
Q

How does someone with SJS/TEN often present?

A

These patients start developing symptoms 1-2 months after starting a drug and often it starts with a flu-like (febrile/prodromal) illnes that involves MUCOSAL IRRITATION, CONJUNCTIVITIS, and DYSURIA. A morbilliform rash may develop or dusky target lesions (these might burn). Lastly comes the skin and mucosal peeling with multisystem involvment.

37
Q

How do you know this is SJS and not just a morbilliform or urticarial drug reaction?

A

MUCOUS MEMBRANE invovlement

***Remember Conjunctivitis is an early sign of SJS***

38
Q

How do you distinguish TEN from SSS in an infant?

A

SSS is RED underneath b/c epidermis is peeling off of the dermis. Remember only the stratum granulosom is affected in SSS

**See the dermal epidermal split below - DDx from histology would be bullus pemphigoid***

39
Q

Why is it important to differentiate between a DRESS SYNDROME and SJS in terms of treatment?

A

DRESS syndrome requires treatment with Coritcosteriods, but corticosteriods INCREASE mortalilty in SJS/TEN.

40
Q

How do you treat someone with TEN/SJS?

A

#1 CRITICAL TO STOP THE OFFENDING DRUG
• You need to put these patients in a burn unit and you need a multidisciplinary team for skin care, eyes, mucous membranes, and high risk infection.

• No matter what MORTALITY IS HIGH

Dermatology Pathology (10 decks)

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