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Teledermatology for suspected skin cancers

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

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