A lonely lesion on a 69 yr old male.  Lonely lesions that are changing and are multi-coloured are of concern and need urgent assessment.

This is the Dermatoscopy view of the lesion in the picture above. The surrounding brown pigment is the remnants of a Solar Lentigo. Centrally there is chaos with blue & grey pigment clods and this makes it highly likely that this is a Melanoma arising within a Solar Lentigo.  The other minor clues include the white lines at right angles to each other under the polarised light. Higher magnification reveals polymorphous blood vessels.  The definition of white lines is that they must be lighter than the surrounding skin.   This MUST go under the microscope - will let you know when I have the histology report.  Histology Melanoma in situ 

Common spots that have usually been present for a long time and which need careful evaluation as they can be a melanoma. These spots appear like this because they are caused by Melanocytes that are present in the deep dermis - hence the blue colour.  Pattern analysis helps as the pigment is uniform (one colour and one pattern) and there are no other clues to malignancy.  All these pictures are benign lesions

49 yr old male  with lesion present for  many months.  You can see the three ulcerated areas and also the arborising and serpentine blood vessels. This is most likely to be  BCC and will need grafting.
Nodular Basal Cell Carcinoma

79 yr old lady who I saw 7 years ago and did a graft for a BCC - clear margins.  New lesion has developed near the old graft site and has been growing steadily over recent months. The old graft site is the the left and you can see the BCC has started invading the graft. This will also need a full thickness graft. 
Aggressive Basal Cell Carcinoma

87 year old lady with a lesion on her left cheek that has been  growing and becoming darker over recent months.  She says that her GP did cryotherapy on it some time ago.  Cryotherapy to a pigmented lesion is not recommended. 
The pattern here is chaotic with thickened reticular lines centrally and moth eaten areas at 3 and 7 o'clock that have within them black dots, broken lines, grey dots and polygons. With these features the lesion must be treated as a lentigo maligna - ie a melanoma in situ on the face.  Treatment options here are a shave biopsy of the entire lesion to confirm the nature of the lesion or complete excision.  I have opted for complete excision and will post the histology when I get it.
Histology - Melanoma in Situ

This lesion is on a 63 yr old lady. It started like an insect bite three weeks ago and has grown rapidly.  The lesion is hard and very raised. It has a central ulceration containing a keratin plug and radial white lines with coiled, spiral and dot blood vessels. This is typical of a Keratoacanthoma however an SCC can behave in the same way so removal is a good choice
Histology - Squamous Cell Carcinoma

This lesion is on the chest of an old sailor.  Nonpigmented lesions can be hard to differentiate however an ulcerated lesion that has branching vessels at 12 o'clock suggests a BCC.  

This is a good example of Psoriasis that has been treated with steroid cream. Untreated psoriasis is likely to have a more erattic pattern of blood vessels covered by thick layers of scale.

Psoriatic nails showing the pitting that is characteristic of this condition