Skin Pathology

Question 1

Layers of the epidermis

Answer 1

Come lets get some beers

Corneum
Lucidium
Granulosum
Spinosum 
Basale

Question 2

What area is affected in Bullous pemphigoid

Answer 2

Dermo-epidernal junction

Basement membrane- deeper bullae

Question 3

What area is affected in pemphigus vulgaris

Answer 3

Intraepidermal

More superficial

Question 4

Clinical features of pemphigoid

Answer 4

Large tense bullae on erythematous base. Often on forearms, groin and axillae. ELDERLY.
Bullae do not rupture as easily as pemphigus

Question 5

Clinical features of pemphigus

Answer 5

Bullae are easily ruptured. Found on skin AND mucosal membranes

Question 6

Histology of pemphigoid

Answer 6

Subepidermal bulla with eosinophils

Linear deposition of IgG along basement membrane

Question 7

Histology of pemphigus

Answer 7

Intraepidermal bulla
Netlike pattern of
intercellular IgG deposits

Question 8

What area does Pemphigus foliaceus affect

What are the clinical features and the diagnosis

Answer 8

o Top layer is very thin so never blisters
o IgG-mediated – outer layer of stratum corneum shears off
o Diagnose with immunofluorescence

Question 9

Clinical features of discoid eczema

Answer 9

o Flexor surfaces

o Very itchy; plaques form

Question 10

Clinical features and pathophysiolofgy of contact dermatitis

Answer 10

o Itchy; latex and nickel
 Itchy  hyperparakeratosis (thickening)
 Epidermis gets thicker  lichenification
o
Pathophysiology:
 Epidermis gets thicker
 Eczema is spongiotic because there is oedema in between the keratinocytes
 T cell mediated and eosinophils are recruited

Question 11

Pathophysiology and clinical features of plaque psoriasis

Answer 11

Extensor surfaces

o Silver plaques (similar to discoid eczema)

o Pathophysiology:
 Normal keratinocyte turnover time = 56 days
 Psoriasis keratinocyte turnover time = 7 days
 Rapid turnover - epidermis thicker
 A layer of parakeratosis (nuclei in S. corneum) forms at the top
 Stratum granulosum disappears as not enough time to form it; and dilated vessels form
 Munro’s microabscesses form, made up from recruitment of neutrophils

Question 12

Clinical features of Lichen planus

Answer 12

o Papules and plaques of purplish-red colour on the wrists and arms
 In mouth it presents as white lines (Wickham striae)

Question 13

Pathophysiology of Lichen planus

Answer 13

 T-lymphocytes have destroyed bottom keratinocytes
 Creates band-like inflammation
 Cannot see where dermis finished, and epidermis starts

Question 14

Clinical features of Seborrhoeic Keratosis

Answer 14

Rough plaques, waxy, “stuck on” appear in middle age / the elderly

Harmless and benign

Question 15

Histopathology of Seborrhoeic keratosis

Answer 15

 Lots of growth and ordered proliferation
 Ordered and benign growth
 “Horn cysts” – epidermis entrapping keratin

Question 16

Characteristics of basal cell carcinoma

Answer 16

o Rolled, pearly-edge, central ulcer, telangiectasia
 “Rodent ulcer” as it burrows away
o Benign but can disfigure
o Occurs in sun-exposed areas

Question 17

Histopathology of BCC

Answer 17

 Dysplastic change
 Cancer from keratinocytes at bottom of epidermis
 Cannot break through the BM  cannot metastasise

Question 18

Bowen’s Disease Characteristics

Answer 18

Pre-malignant
Intra-epidermal squamous cell carcinoma in situ
Flat, red, scaly patches on sun-exposed areas

Question 19

Bowen’s disease histology

Answer 19

Full thickness atypia/dysplasia

Basement membrane intact – i.e. not invading the dermis

Question 20

Squamous Cell carcinoma features

Answer 20

When Bowen’s has spread to involve dermis
Similar clinical features to Bowen’s but may ulcerate
Atypia/dysplasia throughout epidermis,

Nuclear crowding and
spreading through basement membrane into dermis

Question 21

Histopathology of malignant melanoma

Answer 21

atypicalmelanocytes;initiallygrowhorizontallyinepidermis(radialgrowthphase); then grow vertically into dermis (vertical growth phase); vertical growth produces “buckshot appearance” (=Pagetoid cells)

Question 22

Most important prognostic factor of MM

Answer 22

Breslow thickness

Question 23

Clinical features of MM

Answer 23

o	Irregular border							
o	Variable pigmentation						 
o	Bleeding
o	Itchy
o	Growing