Skin Path

Question 1

Define these key terms:

• hyperkeratosis
• parakeratosis
• acanthosis
• acantholysis
• spongiosis
• lentiginous

Answer 1

• Hyperkeratosis - thickening of S. corneum; often increased keratin
• Parakeratosis - retention of nuclei in S. corneum - seen in disorders of increased cell turnover
• Acanthosis - increase in S. Spinosum
• Acantholysis - reduced cohesion between keratinocytes
• spongiosis - intercellular oedema
• Lentiginous - linear pattern of melanocyte proliferation within epidermal basal cell layer

Question 2

Eczema/ dermatitis:

1. atopic
2. contact
3. seborrhoeic

Give 1 characteristic of each

Answer 2

they all have similar histology & present with inflamed, dry itchy rashes

1. atopic - FHx of atopy
   
   • affects flexural ares in older children
   • if chronic get lichenification
2. Contact - type IV hypersensitivity
   
   • erythema, swelling, pruritis
3. Seborrhoeic = inflammatory rxn to a yeast (malassezia)
   
   • infants - cradle cap. Fine scaling in young adults

Question 3

Eczema/ dermatitis: all types have same histology, descibe the acute (2) & chronic (1)

Answer 3

acute

• spongiosis - intercellular oedema
• inflammatory infiltrate in dermis - eosinophils
• dilated dermal capillaries

Chronic

• acanthosis
• crusting/ scaling

Question 4

Psoriasis:

• what is it?
• extensor of flexors affected?
• what is auspitz sign?
• what is koebner phenomenon?

Answer 4

• Chronic inflammatory dermatosis, charactereized by well demarcated red scaly plaques
• affects extensors (in contrast to eczema)
• auspitz sign - pin point bleeding where you rub them
• koebner phenomenon​ - lesions grow at site of trauma

Question 5

Psoriasis - histology (2)

Answer 5

• parakeratosis - retention of nuclei (due to increased cell turnover)
• “test tubes in a rack” appearance - due to clubbing of rete ridges
• munro’s microabscesses

Question 6

Most common form of psoriasis is chonic plaque psoriasis, other forms include:

1. Flexural psoriasis
2. Guttate psoriasis
3. Pustular/ erythodermic psoriasis

1 feature of each

Answer 6

1. flexural - seen later in life
2. Guttate - rain drop lesions seen in children post strep
3. pustular - severe wide spread disease with systemtic symptoms

Question 7

What nail changes are often seen with psoriasis? (3)

Answer 7

Nail changes: (POSH)

• Pitting
• Onycholysis
• subungual hyperkeratosis

NB - psoriasis also assc with arthiritis

Question 8

Lichen planus:

• 5 Ps describing lesions
• what are Wickam’s striae?
• Histology (2)

Answer 8

Aetiology is unknown - thought to be T cell derived

Lesions are ‘pruritic, papules, purple, polygonal & plaques’

Wickam’s striae - forms white lines - often in mouth

Histo

• hyperkeratosis
• saw toothing of rete ridges
• destruction of basal keratinocytes

Question 9

Erythema multiforme:

• classic lesions
• causes (2)
• histology (1)
• if in mouth associated with which emergency?

Answer 9

• classically causes annular target lesions, commonly on hands and feet
• Causes - infection or drugs
• histo - subepidermal bullae
• if in mouth assc with SJS

Question 10

Bullous disease: Pemphigoid

• patthophysiology
• features (1)
• histology (2)

Answer 10

Path - IgG binds to hemidesmosomes of BM > subepidermal bullae

F - usually in elderly, large bullae

Hist - subepidermal bullae with eosinophils, linear deposition of IgG along BM

Question 11

Bullous disease: pemphigus vulgaris

1. pathology
2. Feature (1)
3. histology (2)

Answer 11

Path - IgG bind to desmosomes - intraepidermal bullae

(pemphigus - bullae are superficial, pemphigoid - bullae deep)

F - bullae easily ruptured

Hist - intraepidermal bullae, net like pattern of intercellular IgG deposits, acantholysis

Question 12

Bullous disease: Dermatitis herpetiformsis

• assc with?
• which Ab class & what does it bind ?
• features? (1)

Answer 12

It is associated with coeilacs, get IgA abs binding to BM - subepidermal bullae

F - itchy vesicles on extensor surfaces of elbows

Question 13

Seborrhoeic keratosis: features (2)

Answer 13

Benign lesion - rough plaques, waxy ‘stuck on’ appearance, elderly

Question 14

Actinic keratosis: features (2), hitology (5)

Answer 14

Is a premalginant, Rough sand paperlike scaly lesion in sun exposed areas

Histo: SPAIN

• Solar elastosis
• Parakeratosis
• Atypia/dysplasia
• Inflammation
• Not full thickness

Question 15

Bowen’s disease: what is it? features (2), histology (2)

Answer 15

intra-epidermal carcinoma in situ

flat, scaly patches on sun exposed areas

Histo:

• Full thickness dysplasia
• doesent invade BM - so not a cancer (premalignant)

Question 16

Squamous cell carcinoma: characteristics (1), histo (2)

Answer 16

This is basically when Bowen’s disease has penetrated the BM

clin features similar to Bowen’s, but SCC may also ulcerate

histo - fullthickness dysplasia penetrating BM into dermis

Question 17

BCC: characteritisics (3), histo (1)

Answer 17

AKA rodent ulcer

Slow growing, not metastatic cancer - but locally destructive

pearly surface, telangiectasia

Histo - mass of basal cells pushing down into dermis

Question 18

Malignant melanoma: histo (2), staged using?

Answer 18

Histo - atypical melanocytes

• 1st grow horizontally in epidermis - radial growth phase
• Then vertically into dermis - vertical growth phase

staged - Breslow thickness - most imp prognostic factor

Question 19

Give the 4 subtypes of malignant melanomas, and 1 feature for each

Answer 19

1. Lentigo MM - sun exposed areas of elderly
2. Superficial spreading MM - irregular borders + colour variation
3. Nodular MM - in young ppl
4. Acral lentiginous melanoma - palms/soles & subungual areas

Question 20

SJS: features (3), cause (1)

Answer 20

Derm emergency

F - sheets of skin detachment - <10% SA for SJS, > 30% in TEN

Nikolsky sign +ve (skin can be pushed aside by slight pressure from fingers), mucosal involvment

Cause - Drugs eg. sulfonamide ABs, anticonvulsants