Derm

Question 1

Define blister/bullous

Answer 1

A circumscribed elevated fluid filled lesion

Blister <5mm

Bullous 5mm<

Question 2

List the causes of bullous disorders

Answer 2

Insect bites, burns or pressure, friction

Infective

Impetigo or HZV, VZV

Inflammatory

Drugs, Erthema Multiforme, Vasculitis, Lupus

Inherited

Epidermolysis Bullosa (skin fragility disorder)

Autoimmune

Bullous pemphigoid, Pemphigus, Dermatitis herpetiformis

Question 3

Briefly describe Bullous pemphigoid

Answer 3

Commonest AI blistering disorder

Us, elderly pop

Often sig co-morbidity (Neuro disease esp dementia, Parkinson’s, CVA)

Sig morbidity from disease and its Tx

(Mort 6-40%)

Question 4

Pityriasis versicolor - briefly outline

Answer 4

Yeast infection mainly of torso

Malassezia furfur

Us. commensal but pathogenic in warm, humid conditions

May be mildly itchy

Macular light yellow brown patches (white in darker or tanned skin)

Tx

topical ketoconazole shampoo or oral azole

May need repeat Tx if recurs

Question 5

Name the 4 major cells types in the epidermis

Answer 5

Keratinocytes - produce keratin as portective barrier

Melanocytes - produce melanin pigment and protects cell nuclei from UV radiation-induced DNA damage

Langerhan’s cells - APCs which can activate T-lymphocytes in immune response

Merkel cells - specialised nerve endings for sensation

Question 6

Name the layers of the epidermis

Answer 6

Stratum basale - deepest layer of acitvely dividing cells

Stratum spinosum - differentiating cells

S. granulosum - anuclear cells contains keratohyaline granules. They secrete lipid in to the intercellular spaces.

S. lucidum - in thick skin, pale compact keratin layer

S. corneum - most superficial, layer of karatin

Question 7

Briefly describe the components of the dermis

Answer 7

Collagen (mainly), elastin, and glycosaminoglycans which are synthesised by fibroblasts.

Collectively give strength and elasticity

Also contains, immune cells, nerves, skin appendages as well as lymphatics and blood vessels

Question 8

Erythema nodosum

Answer 8

A hypersens response to variety of stimuli

Causes

Group A ß-haemolytic streptococcus, 1o TB, preg, malignancy, sarcoidosis, IBD, chylamydia, leprosy, drugs (OCP, sulphoamides)

55% - idiopathic

More common in females

Presentation

Discrete erythematous painful nodules which may become confluent

Lesions continue to appear 1-2wks and leave brusie-like discolouration as they resolve

Lesions do not ulcerate and resolve w/o atrophy or scarring

Shins most common site

Investigation

Hx and exam

CXR

Drug Hx

Throat swab, ASOT (Antistreptolysin-O titre), Mantoux, mycoplasma serology

ACE level

Tx

Bed rest, anti-inflamms

Treat underlying cause

Rarely oral corticosteroids

Question 9

Erythema multiforme

Answer 9

Acute self limiting inflamm condition

Hypersens reactions to infection (90%), drug reaction

HSV(>50%) and mycoplasma most common (others hepatitis, HIV)

Us. lasts 1-4wks, can recur

Mucosal involvement absent or limited to one mucosal surface

Clinical Signs

Classical target lesion

Us. localised to acra; site, symmetical, ,ay involve face

Mucosal lesions in 70%

May be extensive

Tx

Symptomatic: topical steroids, analgesics, antihistamines

Oral steroids in severe cases

Prophylactic oral acylclovir for recurrent HSV infection