Pathology of rashes

Question 1

What is hyperkeratosis?

Answer 1

Increased thickness of keratin layer

Question 2

What is parakeratosis?

Answer 2

Persistence of nuclei in the keratin layer

Question 3

What is acanthosis?

Answer 3

Increased thickness of the epidermis

Question 4

What is papillomatosis?

Answer 4

Irregular epithelial thickening

Question 5

What are the four main reaction patterns in rashes?

Answer 5

Spongiotic
Psoriasiform
Lichenoid
Vesiculobullous

Question 6

Which condition is an example of a spongiotic rash?

Answer 6

Eczema

Question 7

Which condition is an example of a psoriasiform rash?

Answer 7

Psoriasis

Question 8

Which conditions are examples of a lichenoid rash?

Answer 8

Lichen planus

Lupus

Question 9

Which conditions are examples of a vesiculobullous rash?

Answer 9

Pemphigoid
Pemphigus
Dermatitis herpetiformis

Question 10

What is a spongiotic rash pattern?

Answer 10

Intraepidermal oedema

Question 11

What can be seen histologically in a psoriasiform rash?

Answer 11

Elongation of the rete ridges

Question 12

What can be seen histologically in a lichenoid rash?

Answer 12

Basal layer damage

Question 13

What can be seen histologically in a vesiculobullous rash?

Answer 13

Blistering

Question 14

What is the Koebner phenomenon?

Answer 14

A new psoriatic lesion may appear at site of trauma

Question 15

What is the pathological process in psoriasis?

Answer 15

Epidermal hyperplasia - keratin migrates from the basal layer to the keratin layer much faster than normal
There is increased epidermal turnover which causes scaly plaques to form on the skin

Question 16

Which sites are most commonly affected by psoriasis?

Answer 16

Extensors (elbow, knee)
Scalp
Sacrum
Hands
Feet
Trunk
Nails

Question 17

What do the plaques in psoriasis look like?

Answer 17

Symmetrical
Well demarcated
Erythematous
Scaly

Question 18

What are some of the nail changes that can occur in psoriasis?

Answer 18

Onycholysis
Nail pitting
Dystrophy
Subungal hyperkeratosis

Question 19

What is acne vulgaris?

Answer 19

A chronic inflammatory disease of the pilosebaceous unit

Question 20

Where is acne vulgaris typically distributed?

Answer 20

Face
Upper back
Anterior chest

Question 21

At what age do patients typically present with acne vulgaris?

Answer 21

14 -17 years in females

16 -19 years in males

Question 22

What is the pathogenesis of acne vulgaris?

Answer 22

There is plugging of the pore by sebum
Bacterial colonisation of the pore occurs, and fills with keratin and sebum creating comedones (whiteheads and blackheads)
These rupture, causing inflammation

Question 23

What is acne rosacea?

Answer 23

Prominent facial flushing exacerbated by sudden change in temperature, alcohol or spicy food
A rash consisting of papules, pustules and erythema but no comedones

Question 24

Where is acne rosacea distributed?

Answer 24

Nose
Cheeks
Chin
Forehead

Question 25

What are immunobullous diseases?

Answer 25

Skin diseases/rashes that have blisters as the primary feature

Question 26

Which patients are typically affected by bullous pemphigoid?

Answer 26

Elderly patients

Question 27

What does the blister in bullous pemphigoid look like?

Answer 27

Large tense bullae on normal skin or erythematous base

Question 28

What is the pathology in bullous pemphigoid?

Answer 28

Splitting at the DEJ - pemphigoiD splits Deep at the DEJ | Circulating IgG antibodies attack the anchors that hold the basal cells to the basement membrane

Question 29

Which areas does bullous pemphigoid tend to affect?

Answer 29

Either localised to one area or widespread over proximal limbs and trunk

Question 30

What is pemphigus?

Answer 30

A rare autoimmune bullous disease resulting in loss of integrity of epidermal cell adhesion

Question 31

What is the most common form of pemphigus?

Answer 31

Pemphigus vulgaris

Question 32

What is the pathogenesis of pemphigus vulgaris?

Answer 32

IgG auto-antibodies made against desmoglein 3 which maintains desmosomal attachments Immune complexes form on cell surface, and there is complement activation and protease release causing disruption of desmosomes This causes acantholysis

Question 33

Which areas does pemphigus vulgaris tend to affect?

Answer 33

``` Face Axillae Scalp Groin Trunk Mucosal tissue e.g. eyes, genitals, mouth, respiratory tract ```

Question 34

In which cases might pemphigus vulgaris be fatal?

Answer 34

Extensive involvement of mucosal tissue e.g. respiratory tract

Question 35

What is Nikolsky sign?

Answer 35

A skin finding in which the top layers of the skin slip away from the lower layers when slightly rubbed

Question 36

Is Nikolsky sign positive or negative in bullous pemphigoid?

Answer 36

Negative

Question 37

Is Nikolsky sign positive or negative in pemphigus?

Answer 37

Positive

Question 38

What do the lesions in pemphigus vulgaris look like?

Answer 38

Flaccid vesicles/bullae – thin roofed Lesions rupture to leave raw areas Erosions rather than bullae

Question 39

What is the prognosis following diagnosis of an immunobullous disease?

Answer 39

Chronic self limiting condition: most patients achieve remission after 3-6 months High mortality if left untreated

Question 40

Which immunobullous disease has a strong association with coeliacs disease?

Answer 40

Dermatitis herpeteformis

Question 41

Which gene is dermatitis herpeteformis associated with?

Answer 41

HLA-DQ2 haplotype

Question 42

What are the lesions in dermatitis herpeteformis?

Answer 42

Intensely itchy symmetrical lesions, often excoriated | Papillary dermal microabscesses

Question 43

Where are the lesions in dermatitis herpeteformis typically found?

Answer 43

Elbows Knees Buttocks