Benign Skin Lesions

Question 1

What are the four key features of benign pigmented lesions?

Answer 1

1. Well-defined margin
2. Even pigmentation
3. Symmetrical
4. Slow or no change over time

Question 2

What genetic mutation is associated with freckles?

Answer 2

One defective copy of the MC1R gene

Question 3

What triggers freckles to appear?

Answer 3

UV exposure

Question 4

What is another name for actinic lentigenes?

Answer 4

Age spots or liver spots

Question 5

Where are actinic lentigenes commonly found?

Answer 5

Face, forearms, and dorsal hands

Question 6

How are congenital melanocytic naevi categorised by size?

Answer 6

Small (<2cm)
Medium (2-20cm)
Giant (>20cm)

Question 7

What is the risk of melanoma in giant congenital melanocytic naevi?

Answer 7

10-15% risk with increasing age

Question 8

At what age are most acquired naevi developed?

Answer 8

1st-2nd decades of life

Question 9

What feature is common in compound naevi?

Answer 9

Slightly elevated or dome-shaped, often pigmented, may have hairs

Question 10

Where are naevus cells located in intradermal naevi?

Answer 10

Entirely in the dermis
(no junctional activity)

Question 11

What is the minimum size for dysplastic naevi?

Answer 11

> 6mm diameter

Question 12

What gene is commonly mutated in familial DN?

Answer 12

CDKN2A gene

Question 12

How do familial dysplastic naevi differ from sporadic ones?

Answer 12

Familial DN has an autosomal dominant inheritance and a much higher risk of melanoma

Question 13

What feature is characteristic of a halo naevus?

Answer 13

A peripheral ring of depigmentation due to inflammatory regression

Question 14

What type of naevus consists of pigment-rich dendritic spindle cells?

Answer 14

Blue naevus

Question 15

Which naevus is pink due to prominent vasculature and commonly occurs in children?

Answer 15

Spitz naevus

Question 16

A 67-year-old woman attends the GP as she is worried about a lesion on her back. Her husband first pointed it out to her last week, but she has no idea how long she has had it. She is worried because her sister has previously had ‘skin cancer’.

In the middle of her back is a 5mm, pigmented, circular, elevated nodule. It has a smooth border and surface and is brown throughout.

What is the most likely diagnosis?

Answer 16

Compound melanocytic naevus

Question 17

A newborn baby boy is being examined by his paediatrician. His examination is unremarkable except for a 1x1cm dark brown oval-shaped lesion on his left forearm. It is flat and has a regular border.

What is the most appropriate action to take? and explain your answer.

Answer 17

Reassure the parents

= The clinical vignette describes a single melanocytic naevus. These are benign skin lesions which may be congenital. They are due to a local proliferation of melanocytes. Most can be left alone and the patient can be reassured, especially if they are young

Question 18

What is another name for seborrhoeic keratosis?

Answer 18

Basal cell papilloma

Question 19

Is seborrhoeic keratosis malignant or benign?

Answer 19

Benign

Question 20

What type of cells proliferate in seborrhoeic keratosis?

Answer 20

Epidermal keratinocytes

Question 21

What is the Leser-Trélat sign?

Answer 21

Eruptive appearance of multiple seborrhoeic keratoses, which may indicate internal malignancy

Question 22

Seborrhoeic keratosis is associated with which malignancy?

Answer 22

Gastric adenocarcinoma

Question 23

Where on the body are seborrhoeic keratoses commonly found?

Answer 23

Face and trunk

Question 23

What is the characteristic appearance of seborrhoeic keratosis?

Answer 23

1. Well-demarcated 2. Raised 3. Brown lesion with a "stuck-on" greasy surface

Question 24

What are some surface features of seborrhoeic keratosis?

Answer 24

Small cysts, depressions, or a warty texture

Question 25

What is the primary treatment approach for seborrhoeic keratosis?

Answer 25

Reassurance – most require no treatment

Question 26

What are the 3 removal options if the patient desires treatment?

Answer 26

Cryotherapy, curettage or laser ablation

Question 27

Patient has a Seborrhoeic Keratosis. What is the usual first-line treatment for his condition?

Answer 27

Cryotherapy

Question 28

A 69-year-old man is concerned about new 'moles' on his back which have increased in number over the past month. He has also had intermittent stomach pain and thinks he has lost some weight recently. His father had malignant melanoma and the patient is very worried that he also has this. On examination, there are many well-demarcated raised brown lesions all over his back. They feel smooth and waxy to touch. The patient says they itch slightly but are not painful and have never bled. They have a 'stuck-on' appearance. Given the most likely diagnosis, which conditions are most associated with it?

Answer 28

gastric or colorectal adenocarcinoma

Question 29

What causes dermatofibroma formation?

Answer 29

Proliferation of fibroblasts triggered by an insect bite or minor trauma

Question 30

In which patient group is dermatofibroma more common?

Answer 30

Immunosuppressed patients

Question 31

How does dermatofibroma typically appear?

Answer 31

Firm, skin-colored or brownish lesion that dimples when pinched

Question 32

Is dermatofibroma typically painful?

Answer 32

No, but it can occasionally be itchy

Question 33

What dermoscopic feature suggests dermatofibroma

Answer 33

Scar-like white center.

Question 34

Is dermatofibroma benign or malignant?

Answer 34

Completely benign

Question 35

When should a biopsy be considered?

Answer 35

If the diagnosis remains uncertain after dermoscopy

Question 36

What is the treatment for dermatofibroma?

Answer 36

Reassurance – no excision required

Question 37

Which procedure facilitates the histological diagnosis of a dermatofibroma?

Answer 37

Local excision

Question 38

What is the classic feature of a dermatofibroma?

Answer 38

Dimple

Question 39

A 27-year-old woman presents to the GP with a lesion on her lower leg. She does not know how long it has been there. On examination, it is a light brown nodule that dimples when squeezed. What is the most likely diagnosis?

Answer 39

Dermatofibroma

Question 40

A 22-year-old woman books a doctor's appointment because she is worried about a pink bump which she has recently noticed on her left shin. It is not causing her any physical symptoms and she denies any recent trauma or insect bites to the leg. On examination, the lesion is 1cm in diameter, has smooth round borders and the overlying skin dimples when it is squeezed. Given the likely diagnosis, what is the most common associated complication?

Answer 40

No complications