Benign Skin Tumours

Question 1

What are benign skin lesions?

What are the features?

Answer 1

A benign skin lesion = non-cancerous skin growth

=> symmetry in shape, colour, structure

=> stable or slowly evolving

=> absence of spontaneous bleeding

Benign lesions can be classified by their cellular origin:

=> melanocytic

=> keratinocytes

=> vascular

=> fibrous

Question 2

What are the common benign skin lesions of melanocytes origin?

Answer 2

Ephilis

Lentigo simplex

Melanocytic naevus

Question 3

What are ephilides?

Answer 3

AKA freckles - well defined small brown macules with:

=> 1-4mm in diameter

=> Tan or brown colour

=> Located in areas exposed to the sun i.e. face/forearms

=> Increased melanin deposition in the basal keratinocyte on biopsy

Question 4

What is lentigo simplex?

Answer 4

Lentigo simplex is not sun-induced.

=> well circumscribed, uniform brown to black macule

=> located on mucous membrane or skin, including palms and soles

=> develops during childhood or young adult life

Question 5

What is a melanocytic naevus?

Answer 5

Melanocytic naevus can be histologically classified as junctional, compound or dermal naevus depending on the location of naevus cells.

1. A junctional naevus has naevus cells at the base of the epidermis

=> well circumscribed pigmented macule with regular but fading borders

=> number and appearance of junctional naevi depends on sun exposure, fluctuating hormonal levels and immunosuppression

2. Compound naevus has papular and flat components due to junctional and dermal naevus cells

=> usually pink or brown, dome shaped papule surrounded by macular pigmentation

=> most lesions arise during childhood

3. Dermal naevus characterised by naevus cells in the dermis

=> elevated papule

=> brown, blue, black or skin coloured

=> arise in childhood but mature during early adult life

Question 6

Melanocytic naevi = most common benign neoplasm

=> start as flat brown macules with proliferation of melanocytes at the dermo-epidermal junction (junctional naevi)

=> later downward growth of melanocytes into the dermis (compound naevi) ; mole becomes raised, palpable, maturing into an intradermal naevus with loss of pigment

Answer 6

Atypical naevi:

=> dysplastic features

=> increased risk of melanocytes

Familial atypical mole syndrome = increased number of atypical naevi and a high lifetime risk of melanoma

=> long-term follow-up

Question 7

What are the common benign keratinocytic lesions?

Answer 7

Solar lentigo

Seborrhoeic keratosis

Epidermal cysts

Corn/calluses

Sebaceous hyperplasia

Question 8

What is a solar lentigo?

Answer 8

Sun-induced pigmented macule

=> vary in size

=> usually tan to brown-black

=> uniformly pigmented lesions with a sharp border

=> arise in adult + prevalent in older people

Question 9

What is seborrhoeic keratosis?

Answer 9

Caused by overgrowth of basal keratinocytes

=> variable warty plaque

=> dull, verrous or waxy surface with a classical stuck-on appearance

=> yellow, brown or black or multi-coloured

=> Skin biopsy: papillomatous epidermis with thick basal layer + presence of keratin-filled cysts

=> older adults

Question 10

What is epidermal cyst?

Answer 10

Follicular nodule with a central punctum

=> skin-coloured, off-white dome-shaped papule or nodule

=> cheesy or yellow-ish keratin expressed through the punctum or removed by incising the cyst

=> epidermal cyst is lined with flat epidermal cells and has a granular layer surrounding laminated keratin

Question 11

What are corn / calluses?

Answer 11

Localised areas of thickened skin induced by pressure

1. Corn = small tender papule
2. Callus = thickened non-tender plaque

=> both located on pressure area of the hand and foot

=> soft corn = scaly plaque

=> hard corn = firm papule with a translucent centre core

Question 12

What is sebaceous hyperplasia?

Answer 12

Sebaceous hyperplasia = occurs on the forehead and cheeks of adults

=> one or more dome-shaped papule with central umbilication

=> uniform yellow lobules seen on dermascopy

Question 13

What are the common lesions of vascular origin?

Answer 13

Cherry angioma

Pyogenic granuloma

Question 14

What are pyogenic granuloma?

Answer 14

Vascular response to trauma and bacterial infection

=> rapidly growing friable nodule on fingers, toes or facial sites

=> yellow to violaceous colour

=> pyogenic granuloma is surrounded by a scaly collarette

Question 15

What are cherry angioma?

Answer 15

Angioma due to proliferation of the endothelial cells

=> superficial angioma is a bright red colour

=> deeper angioma is purple or blue

=> nodular or macular lesions in varying sizes

Question 16

What are the most common fibrous lesions?

Answer 16

Dermatofibroma : reactive lesion that presents as one or more firm dermal papules

=> pink, tan or brown

=> dimple when pinched

=> skin biopsy shows fibrohistiocytic cell proliferation with entrapment of collagen at the periphery

Question 17

What are the common subcutaneous lesions?

Answer 17

Lipoma:

=> most common benign soft-tissue tumour

=> soft, rubbery, freely mobile mass usually found on the back, neck, trunk

=> skin biopsy shows white adipose tissue in subcutaneous layer

Question 18

What is a skin tag?

Answer 18

Most common type of skin tag aka acrochordon

=> soft, fleshy papule, always pedunculated

=> vary in diameter

=> biopsy shows fibrovascular core covered by normal squamous epithelium

Question 19

What are keloids and hypertrophic scars?

Answer 19

Abnormal wound healing with excessive dermal fibrosis => hypertrophic scars and keloid formation

=> remains confined to borders of the original wound + regress spontaneously

Keloids can arise spontaneously or after minimal trauma => proliferate and enlarge beyond the wound margins

=> itchy

=> affects young, dark skinned adults

=> common on shoulders, upper back, chest, earlobes and chin

*treatment = silicone gel, dressings, pressure garments, cryotherapy and intralesional corticosteroids