Disease Profiles: Benign Skin Lesions

Question 1

What is the Leser-Trelat sign?

Answer 1

Eruptive appearance of many seborrhoeic keratoses may indicate internal malignancy

Question 2

Describe the appearance of seborrhoeic keratoses

Answer 2

Very well demarcated, raised, usually brown coloured lesion with a ‘stuck on’ appearance (greasy hyperkeratotic surface)

Surface typically appears warty

Question 3

How would you manage seborrhoeic keratoses?

Answer 3

Most need no treatment but can remove by cryotherapy or curettage

Question 4

Describe the appearance of congenital naevi

Answer 4

Flat or slightly elevated with a smooth surface, uniform pigmentation

Question 5

Describe the histology of actinic lentigines (age/liver spots)

Answer 5

Elongated rete ridges in the epidermis, increase in melanin and basal melanocytes

Question 6

What is a blue naevus?

Answer 6

Entirely dermal naevi that consists of pigment rich dendritic spindle cells

Question 7

Why might larger congenital naevi need to be excised?

Answer 7

Larger lesions have a 10-15% risk of melanoma with increase in age

Question 8

People with freckles have one defective copy of which gene?

Answer 8

MC1R

Question 9

Describe the histology of dysplastic naevi

Answer 9

Architectural atypia and cellular atypica, with a host reaction of fibrosis and inflammation

Epidermis not effaced (unlike MM)

Question 10

What is a halo naevus?

Answer 10

Rare naevi which has a peripheral halo of depigmentation

Show inflammatory regression and are overrun by lymphocytes

Question 11

What causes actinic lentigines (age/liver spots)?

Answer 11

Long term UV exposure (sun damage)

Question 12

What causes usual type acquired naevi?

Answer 12

Usual type acquired naevi are compound - clusters of melanocytes at dermoepidermal junction, and groups of cells in dermis (at sites where the melanocyte: keratinocyte ratio has broken down)

This process may be immune regulated

Question 13

Define seborrhoeic keratosis

Answer 13

Benign proliferation of epidermal keratonoytes (also called basal cell papillomas)

Question 14

Where do actinic lentigines (age/liver spots) typically occur?

Answer 14

Face, forearms and dorsal hands (sun-exposed sites)

Question 15

What causes intradermal naevi?

Answer 15

Naevus cells in the dermis - all junctional activity ceased so entirely dermal

Question 16

Which type of naevi occur in adolescence/early adulthood?

Answer 16

Usual type acquired naevi (compound)

Question 17

What are sporadic dysplastic naevi?

Answer 17

Benign acquired melanocytic neoplasms, risk of MM slightly raised

Some patients may have genetic predisposition to developing lots of atypical naevi → significantly increased MM risk

Question 18

What is a spitz naevus?

Answer 18

Usually occur <20 years, consist of large spindle and/or epithelial cells, pink colour due to prominant vasculature, may closely mimic melanoma but are mostly benign

Question 19

Which types of naevi are found in babies?

Answer 19

Congenital naevi (junctional)

Question 20

Describe the appearance of intradermal naevi

Answer 20

Dome shaped, verrucous, pedunculate, or sessile, often flesh coloured, occasionally hairy and may display surface telangiectasia

Question 21

What causes freckles (ephelis)?

Answer 21

Patchy increase in melanin pigmentation that occurs after UV exposure

Question 22

Describe the appearance of usual type acquired naevi

Answer 22

Lesions slightly elevated or dome shaped, often pigmented, hairs may project from surface

Question 23

Which type of naevi occur in adulthood?

Answer 23

Intradermal naevi (dermal)

Question 24

In which skin type are freckles (ephelis) most common?

Answer 24

Fair skin

Question 25

What are melanocytic naevi?

Answer 25

Common moles

Question 26

What causes congenital naevi?

Answer 26

Congenital naevi are junctional - proliferation of melanocytes leading to clusters of cells at the dermoepidermal junction