Benign Skin Lesions Flashcards
Features of benign pigmented lesions
Well defined margin
Even pigmentation
Symmetrical
Consistent over time
Common name for ephelides
Freckles
What are ephelides
Patchy increase in melanin pigmentation which occurs after UV exposure
Who is most likely to have freckles
People with fair skin and red hair
Genetics of ephelides
One defective copy of MC1R gene
Common name for actinic lentigines
Age spots or liver spots
What are actinic lentigines associated with
Long term UV exposure
Where do actinic lentigines usually present
Face, forearms and dorsal hands
Histology of actinic lentigines (2)
Elongated rate ridges in the epidermis
Increase in melanin and basal melanocytes
Another name for melanocytic naevi
Moles
Naevi present in childhood
Junctional naevi
Naevi present in adolescence and early childhood
Compound naevus
What are Congenital melanocytic naevus
Visible pigmented proliferations in the skin that are present at birth
Junctional naevus
Naevus cells cluster in the dermoepidermal junction
What can larger congenital melanocytic naevi show
Hypertrichosis
What is hypertrichosis
Excessive hair growth
How do we acquire usual type naevi
During infancy the melanocyte: keratinocyte ratio breaks down at a number of cutaneous sites which allows the formation of simple naevi
Intradermal naevi
All Junctional activity has ceased, entirely dermal
Dysplastic naevi presentation
Generally >6 mm in diameter, with varied pigment and border asymmetry
What is the most common type of dysplastic naevi
Sporadic
Lifetime melanoma risk in a patient with genetic predisposition to developing dysplastic naevi
Up to 100%
Give an example of a gene which can cause predisposition to development of dysplastic naevi
CDKN2A
Histology of dysplastic naevi
Architectural atypical and cellular atypia with a host reaction of fibrosis and inflammation
Epidermis is NOT effaced
Halo naevi
Peripheral halo of depigmentation
Blue naevi
Entirely dermal and consist of pigment rich dendritic spindle cells
Spitz naevus
Pink colour due to prominent vasculature
Closely mimic melanoma
What is another name for a seborrhoeic keratosis
Basal cell papilloma
What is a seborrhoeic keratosis
Benign proliferation of epidermal keratinocytes
Lesser-trelat sign
Sudden onset or increase in the number and size of seb K may indicate internal malignancy
What malignancy does lesser-trelat sign usually indicate
GI adenocarcinoma
Where are seb K’s usually found
Face and trunk
Presentation of seb K
Well demarcated, raised, brown coloured lesion
Greasy hyperkeratotic surface
Small horn cysts/depressions
Management of a seb K
REASSURANCE
What is a dermatofibroma
Proliferation of fibroblasts induced by reaction to insect bite or minor trauma
In which patients are dermatofibromas more common
Immunosuppressed patients
Clinical presentation of a dermatofibroma
Unchanging firm lesion, skin coloured or brownish
Feel like they have a stone in them
Occasionally itchy
What does a positive dimple sign indicate
Dermatofibroma
What causes a dimple sign
Connections of the lesion to deeper structures in the skin such as collagen bundles
Presentation of a dermatofibroma when using a dermoscope
Scar-like white centre
Management of dermatofibroma
REASSURANCE
