Basic dermatoscopy

Created 2017.

There are many systems and algorithms.  

• Conventional pattern analysis with morphological terminology has been shown to be very accurate. But it’s complicated, and takes a long time to learn. 
• Modified pattern analysis described by Harald Kittler uses descriptive terminology and is easy to learn, but sometimes clumsy.
• Compare "yellow dot surrounded by skin-coloured circle surrounded by unfocussed curved thick red lines and sometimes angulated brown lines" (descriptive method) with "strawberry pattern" (morphological method).
• People who have learned both methods tend to use a combination of morphological and descriptive terms.

Modified pattern recognition

Summary

• Skin lesions are made up of basic dermatoscopic elements.
• The elements group together to form patterns.
• These terms describe pigment/melanin and blood/blood vessels.

The 3 most basic elements are:

• Lines
• Clods
• Structureless zones (no lines or clods)

Other elements are:

• Dots (smaller than clods)
• Circles (joined-up lines)
• Pseudopods (clod on the end of a line)

Colours in dermatoscopy:

• Melanin: black, dark brown, light brown/tan, grey, blue from superficial epidermis to deep dermis
• Keratin: white, yellow
• Blood: reddish black, red, purple, blue

Arrangements of lines include:

• Network / reticular pattern
• Lattice pattern
• Radial pattern
• Parallel pattern
• Curved parallel lines

Structures can be:

• Peripheral
• Central
• Scattered
• Grouped

A benign skin lesion has symmetrical structures and patterns

• Its shape may or may not be symmetrical
• It is made up of elements forming 1, 2 or 3 patterns
• It usually has only 1 or 2 colours

A malignant skin lesion rarely has symmetrical structures or patterns

• It includes ≥ 2 elements / patterns, usually ≥ 3
• These are distributed irregularly
• Often there are ≥ 5 colours
• Destructive lesions can lose lines and clods
• Grey and white structures often  represent regression and/or scarring