T2: Approach to diagnosis

Question 1

Morphology

Macule

Answer 1

• flat, circumscribed area of skin
  discolouration
• < 0.5-1 cm

Question 2

Morphology

Papule

Answer 2

• solid raised lesion
• < 0.5-1 cm

Question 3

Morphology

Nodule

Answer 3

• solid raised lesion
• > 0.5-1 cm
• goes deeper into dermis than papule

Question 4

Morphology

Tumour

Answer 4

• solid mass
• > 1 cm

Question 5

Morphology

Plaque

Answer 5

• circumscribed, solid, raised flat topped elevated area of skin
• > 0.5-1 cm

Question 6

Morphology

Vesicle

Answer 6

• raised lesion
• filled with clear fluid
• “small blister”
• < 0.5-1 cm

Question 7

Morphology

Bulla

Answer 7

• circumscribed fluid filled lesions
• “big blister”
• > 0.5 cm

Question 8

Morphology

Pustule

Answer 8

• circumscribed, elevated lesion
• contains pus

Question 9

Morphology

Wheal

Answer 9

• transient oedema in dermis

Question 10

Morphology

Abscesses

Answer 10

• large subcutaneous collection of pus

Question 11

Morphology

Cyst

Answer 11

• epithelium lined cavity containing fluid/sold material

Question 12

Morphology

Ulcer

Answer 12

• area of destruction of epidermis

Question 13

Morphology

Fissure

Answer 13

• crack in skin

Question 14

Morphology

Annular lesion

Answer 14

• round lesion
• clear in centre

Question 15

Morphology

Purpura

Answer 15

• area of RBCs in skin
• petechiae: smaller than purpura
• palpable purpura = vasculitis
• deep red, red purple

Question 16

Morphology

Ecchymosis

Answer 16

• bruise
• over large area
• purple, purple blue, green, yellow

Question 17

Distribution

Acral

Answer 17

• hands
• feet
• sometimes face

Question 18

Distribution

Dermatomal

Answer 18

• along nerve supply distribution

Question 19

Distribution

Flexural

Answer 19

• under arms/breasts
• in the groin

Question 20

Distribution

Follicular

Answer 20

• spread in hair follicles

Question 21

Distribution

Photo distribution

Answer 21

• where sun gets on skin

Question 22

Distribution

Seborrhoeic

Answer 22

• scalp, central chest, axillae, groin area
• sometimes on face

Question 23

Colour

Hyperpigmentation

Answer 23

• darker than patients normal skin colour (melasma)

Question 24

Colour

Hypopigmented

Answer 24

• lighter than patients normal skin colour

Question 25

Colour

Depigmented

Answer 25

• no pigment (vitiligo)

Question 26

Procedure

Scrapings/clippings

Answer 26

• take blade and scrape over lesion
• KOH prep
  remove material
  place on glass slide
  10-20% KOH for few minutes
  coverslip
  apply heat + pressure
  microscopy

Question 27

Procedure

Skin biopsy

Answer 27

• incisional
• excisional
• punch

Question 28

Procedure

Patch testing

Answer 28

• done to tests for allergies
• fill patches with allergens and assess skin