Disease Profiles: Benign Skin Lesions Flashcards
What is the Leser-Trelat sign?
Eruptive appearance of many seborrhoeic keratoses may indicate internal malignancy
Describe the appearance of seborrhoeic keratoses
Very well demarcated, raised, usually brown coloured lesion with a ‘stuck on’ appearance (greasy hyperkeratotic surface)
Surface typically appears warty
How would you manage seborrhoeic keratoses?
Most need no treatment but can remove by cryotherapy or curettage
Describe the appearance of congenital naevi
Flat or slightly elevated with a smooth surface, uniform pigmentation
Describe the histology of actinic lentigines (age/liver spots)
Elongated rete ridges in the epidermis, increase in melanin and basal melanocytes
What is a blue naevus?
Entirely dermal naevi that consists of pigment rich dendritic spindle cells
Why might larger congenital naevi need to be excised?
Larger lesions have a 10-15% risk of melanoma with increase in age
People with freckles have one defective copy of which gene?
MC1R
Describe the histology of dysplastic naevi
Architectural atypia and cellular atypica, with a host reaction of fibrosis and inflammation
Epidermis not effaced (unlike MM)
What is a halo naevus?
Rare naevi which has a peripheral halo of depigmentation
Show inflammatory regression and are overrun by lymphocytes
What causes actinic lentigines (age/liver spots)?
Long term UV exposure (sun damage)
What causes usual type acquired naevi?
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
Define seborrhoeic keratosis
Benign proliferation of epidermal keratonoytes (also called basal cell papillomas)
Where do actinic lentigines (age/liver spots) typically occur?
Face, forearms and dorsal hands (sun-exposed sites)
What causes intradermal naevi?
Naevus cells in the dermis - all junctional activity ceased so entirely dermal
Which type of naevi occur in adolescence/early adulthood?
Usual type acquired naevi (compound)
What are sporadic dysplastic naevi?
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
What is a spitz naevus?
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
Which types of naevi are found in babies?
Congenital naevi (junctional)
Describe the appearance of intradermal naevi
Dome shaped, verrucous, pedunculate, or sessile, often flesh coloured, occasionally hairy and may display surface telangiectasia
What causes freckles (ephelis)?
Patchy increase in melanin pigmentation that occurs after UV exposure
Describe the appearance of usual type acquired naevi
Lesions slightly elevated or dome shaped, often pigmented, hairs may project from surface
Which type of naevi occur in adulthood?
Intradermal naevi (dermal)
In which skin type are freckles (ephelis) most common?
Fair skin
What are melanocytic naevi?
Common moles
What causes congenital naevi?
Congenital naevi are junctional - proliferation of melanocytes leading to clusters of cells at the dermoepidermal junction
