Urticaria (hives)

 

Transient skin eruptions

fluid leaves the blood vessels and then is reabsorbed

can also be accompanied by difficulties breathing

differential:

Urticaria (hives) can accompany thyroid disease, connective tissue disease, hepatitis, or malignancy. However, it is very nonspecific and usually none of these, so shotgun investigations are not normally helpful.

often caused by allergy to drugs, food, etc

 

treatment:

start with non-sedating antihistamine ie Ceterazine

 

purpura

Purpura are areas of red blood cell extravasation in the skin and mucous membranes (bleeding under the skin)

petechiae are areas of cutanous hemorrhae 3-5 mm, while ecchymosis is an area of more extensive hemorrhage (more than 2 cm)

 

As purpura are extravascular, they are non-blancheable. Pressing on them will not make them disappear.

 

 

thrombocytopenia

clotting deficiencies

vasculitis (palpable, more than the others...)

• infections
• drugs
• inflammation
• connective tissue disease

Blisters and Bullae

Blisters and bullae are both water-filled vesicles. Blisters are 1 cm and below, while bullae are larger.

 

BListers are edema under the skin.

a well circumscribed elevated lesion that contains fluid.

Old blisters that have collapsed can be hard to diagnose.

blisters can occur at any level

blisters develop when there is cleavage in the skin.

subcorneal edema results from...

 

subepidermal - below basement membrane

 

an eroded area is often due to superficial blisters with a thin roof to it. Deeperly involved blisters will be a bit stronger.

 

Blistering disorders

can be classificed

• congenital
• infectious
• drug induced
• imm
• physical
• eczema
• miscellaneous (radiation, etc)

lines of blisters can result from contact with poison ivy.

HSV induced blisters can cause necrosis and inflammation

 

this is on the exam

pemphigus

 

bullous pemphigoid

• subepidermal blistering disease
• more common in elderly,
• immuno in basement membrane zone, above lamina densa (+ve in 7-080% of pts)
• forms in a linear band
• much more common than pemphigus, with better outcomes
• titres do not usually correlate with disease severity
• characteristically large tens blisters, often on red skin
• most common in lower abd, upper inner arms and legs flexural areas of forearms
• Nikolsky's sign
• a lot of pruritis
• blisters heal quickly, without scarring
• can be treated with topical steroids if disease is localized, though oral drugs can also be used. steroid-sparing azithioprine can also be used

 

eryhtema multiforme

• acute self limied
• reaction to a variety of toxins, esp drugs or infections
• characteristic target lesion, with blister at centre
• usually last 2-3 weeks
• frequent hyperpigmentation

minor: relatively common, peak in 20-40

• may be assoc with HSV, with viral symptoms appearing a few weeks before
• though also idiopathic
• likely cell-mediated immune rxn
• interface dermititis with degen at D-E jcn, with papp edema and necrosis
• intra and sub epi blisters
• immunofluorescence is nonspecific and not helpful

major: Stevens-Johsnson syndrome

• most caused by drigs
• mycoplasma, mononucleosis, adenovisurs
• sulfa drugs, toehr
• over 50% have signgif systemic symtoms, and many are admitted to ICU or burn unit
• multi organ involvment
• 10-90% of body can be affected
• prominent mucosal involvment
• treatment is difficult and complex and requires multidisciplinary care
• signifianct morbidity

dermatitis herpetiformis

subepidermal

red juicy papules, vesicles and plaques

clustering is herpes-like

intense pruritis

any age

persists indefinitely

associated with celiac disease

autoimmune disease

PMNs collect in dermal papillae

IgA and PMN mediated

severe burning and itch

symmetrical distributation, on extensor of elboxus others

rare mucosal involvment

treat with sulfones, dapsone, and sulfapyridine, with rapid improvement

gluten-free diet

 

toxic epidermal necrolysis

reaction ro drugs, esp sulfa NSAIDs, anticonvulstats, and allopurinol

extremely rare

full thickness necrosis of epidermis, skin comes off in sheets

skin pain is prominent and early

rapid evolvement

several mucosal sites and multiple organ failure

rash - morbiliform or diffuse erythema

positive Nikulsky's sign

treat in ICU or burn unit

History

pruritus (itching)

Physical Exam

Lab Investigations

Diagnostic Imaging