This lesion is on the arm of a 6 yr old girl.
This is typical of a Spitz nevus which often occur on the limbs of fair skinned children. Occasionally they need to be removed due the possibility of them being a Melanoma

These lesions come up quickly  usually on sun exposed areas and will often disappear after a few months.  The problem with them is that it is hard to differentiate clinically and histopathologically between this benign condition and an aggressive Squamous Cell Carcinoma (SCC).  Here are two good examples.  There is a low threshold for removing these. 

This spot has been present on the arm of this lady for 12 months.  An observant GP noticed it when he was consulting her husband.  The first thing about it is that it is lonely - beware.  The next thing is that it is black and scaly.

The next picture has been taken using a dermoscope and shows many features that suggest a Melanoma.  The things to note are that there are radial lines with pseudopods, black / grey and blue pigment with clods peripherally.  The white lines are related to scarring deep in the dermis and is the bodies attempt to control the lesion. 

This elderly man has been a sailor and lips get a hammering from the sun.  Too often people forget to apply sunscreen to their lips - it is very important.   The picture shows a an SCC - squamous cell carcinoma. 

This next picture is of the lip of a lady who has also spent many hours on the ocean.  This lesion is not a skin cancer although it would almost certainly become a skin cancer if left. 

Spots on the feet can be a problem.  These ones are not. 

This one has one colour and the pattern is regular

This one does have dark lines crossing the ridges of the skin however they are not thickened so this one is also okay 

Make sure your scalp is checked  - Here are two aggressive Basal Cell Cancers 

This lesion appeared on the scalp over a period of three days.  There was a creeping sensation under the skin associated with pain in the area.  The track you see on the picture is the virus travelling down the nerve fibres.  This need treatment with Zovirax  which should be started as soon as possible. 

This elderly lady was aware that this patch had appeared on her cheek six months ago and was growing rapidly.   Looking at the lesion it appears to be typical of a Solar lentigo however the story made it important to do a biopsy.  The biopsy shows that it is a Lentigo Maligna - Melanoma of the face. 

This next picture is what we usually see when a Lentigo Maligna is found on the face

This lesion is on the chest of a middle aged lady  and has changed recently.  There is a central Keratin plug with increased vascularity  and white scar like lines.  This could easily be an SCC however it is a benign Seborrheic Keratosis

This lesion is on the back of the same lady  and has changed recently.  There is a central Keratin plug with increased vascularity  and white scar like lines.  This could easily be an SCC however it is a benign Seborrheic Keratosis