Benign Skin Diseases

Question 1

Seborrhoeic keratosis

Answer 1

Most commonly arise in patients over the age of 50 years, often idiopathic
Equal sex incidence and prevalence
Usually multiple lesions over face and trunk
Flat, raised, filiform and pedunculated subtypes are recognised
Variable colours and surface may have greasy scale overlying it
Treatment options consist of leaving alone or simple shave excision

Question 2

Congenital melanocytic naevi

Answer 2

Typically appear at, or soon after, birth
Usually greater than 1cm diameter
Increased risk of malignant transformation (increased risk greatest for large lesions)

Question 3

Junctional melanocytic naevi

Answer 3

Circular macules
May have heterogeneous colour even within same lesion
Most naevi of the palms, soles and mucous membranes are of this type

Question 4

Compound naevi

Answer 4

Domed pigmented nodules up to 1cm in diameter

Arise from junctional naevi, usually have uniform colour and are smooth

Question 5

Spitz naevus

Answer 5

Usually develop over a few months in children
May be pink or red in colour, most common on face and legs
May grow up to 1cm and growth can be rapid, this usually results in excision

Question 6

Atypical naevus syndrome

Answer 6

Atypical melanocytic naevi that may be autosomally dominantly inherited
Some individuals are at increased risk of melanoma (usually have mutations of CDKN2A gene)
Many people with atypical naevus syndrome AND a parent sibling with melanoma will develop melanoma

Question 7

Epidermoid cysts

Answer 7

Common and affect face and trunk
They have a central punctum, they may contain small quantities of sebum
The cyst lining is either normal epidermis (epidermoid cyst) or outer root sheath of hair follicle (pilar cyst)

Question 8

Dermatofibroma

Answer 8

Solitary dermal nodules
Usually affect extremities of young adults
Lesions feel larger than they appear visually
Histologically they consist of proliferating fibroblasts merging with sparsely cellular dermal tissues

Question 9

Painful skin lesions

Answer 9

Eccrine spiradenoma
Neuroma
Glomus tumour
Leimyoma
Angiolipoma
Neurofibroma (rarely painful) and dermatofibroma (rarely painful)