What is a benign skin lesion?
A benign skin lesion is a non-cancerous skin growth.
Who gets benign skin lesions?
Any individual from any age group can present with a benign skin lesion.
What are the features of benign skin lesions?
The features in common for benign skin lesions include:
- Symmetry in shape, colour and structure
- Stable or slowly evolving
- Absence of spontaneous bleeding (bleeding or ulceration may be due to recent injury).
Benign lesions can be classified by their cellular origin: melanocytic, keratinocytic, vascular, fibrous, fat, and so on,
Which are the common melanocytic lesions?
Common benign skin lesions of melanocytic origin include the ephilis, lentigo simplex, and melanocytic naevus (mole).
Ephilides are genetically determined well-defined small brown macules with the following characteristics:
- 1–4 mm in diameter
- Tan or brown colour
- Located in areas exposed to the sun such as the face and forearms.
- Increased melanin deposition in the basal keratinocyte on biopsy [1,2].
Lentigo simplex is not sun-induced. It has the following characteristics:
- Well-circumscribed, uniform brown to black macule
- Located on mucous membrane or skin, including palms and soles
- Develops during childhood or young adult life [1,2].
A melanocytic naevus can be histologically classified as a junctional, compound, or dermal naevus depending on the location of nests of naevus cells.
A junctional naevus has naevus cells at the base of the epidermis.
- A junctional naevus is well-circumscribed pigmented macule with regular but fading borders.
- The number and appearance of junctional naevi depend on sun exposure, fluctuating hormonal levels, and immunosuppression [1,3].
Flat melanocytic lesions
A compound naevus has papular and flat components due to junctional and dermal naevus cells.
- The compound naevus is usually a pink or brown, dome-shaped papule surrounded by macular pigmentation .
- Most lesions arise during childhood.
A dermal naevus is characterised by naevus cells in the dermis.
- The dermal naevus is an elevated papule.
- It can be brown, blue, black or skin coloured.
- Dermal naevi arise in childhood but mature during early adult life.
Which are the common keratinocytic lesions?
Benign keratoses include solar lentigo and seborrhoeic keratosis.
A solar lentigo is a sun-induced pigmented macule.
- Solar lentigines vary from small to large size and are usually tan to brown-black.
- The lesions are mostly uniformly pigmented with a sharp border.
- They arise in adult life and are prevalent in older people [1,2].
Seborrhoeic keratosis presents as a variable warty plaque.
- Seborrhoeic keratosis has a dull, verrucous, or waxy surface with a classical stuck-on appearance.
- The shape and structure are often irregular and varies over time.
- They can be yellow to brown to black in colour or made up of several colours.
- Skin biopsy reveals a papillomatous epidermis with a thick basal layer and presence of keratin-filled cysts [1,4].
Epidermoid cyst is a follicular nodule with a central punctum.
- This type of cyst can be skin-coloured to off-white and is a dome-shaped papule or nodule
- Cheesy or yellowish keratin can be expressed through the punctum or removed by incising the cyst.
- The epidermal cyst is lined with flat epidermal cells and has a granular layer surrounding laminated keratin [1,2].
Corns and calluses are localised areas of thickened skin induced by pressure
- A corn (small tender papule) or callus (thickened non-tender plaque) is most often located on a pressure area of the hand or foot.
- A soft corn is a scaly plaque while hard corn is a firm papule with a translucent central core [1,2].
Corns and calluses
Sebaceous hyperplasia occurs on the forehead and cheeks of adults.
- It presents as one or more dome-shaped papules with central umbilication.
- Uniform yellow lobules are seen on dermoscopy [1,2].
Which are the common lesions of vascular origin?
An angioma is due to the proliferation of the endothelial cells.
- A superficial angioma is a bright red colour and a deeper angioma is purple or blue.
- Angiomas are commonly nodular or macular lesions of varying sizes.
A pyogenic granuloma is a vascular response to trauma and bacterial infection.
- It presents as a rapidly growing friable nodule on fingers, toes, or facial sites.
- They have a yellow to violaceous colour.
- The pyogenic granuloma is surrounded by a scaly collarette.
Which are the common fibrous lesions?
Dermatofibroma is a reactive lesion that presents as one or more firm dermal papules.
- The dermatofibroma is pink, tan or brown.
- It forms a dimple when pinched.
- A skin biopsy shows fibrohistiocytic cell proliferation with entrapment of collagen at the periphery [1,2].
Which are the common subcutaneous lesions?
The lipoma is the most common benign soft-tissue tumour.
- A lipoma presents as a soft, rubbery, freely mobile mass that is usually found on the back, neck, or trunk.
- Skin biopsy shows white adipose tissue in the subcutaneous layer [1,2].
What is a skin tag?
The most common type of skin tag is also called acrochordon.
- An acrochordon is a soft, fleshy papule that is almost always pedunculated.
- They vary in diameter from 1 to 6 mm.
- On biopsy, there is a fibrovascular core covered by normal squamous epithelium .