Monday, April 5, 2021

How to use this website in day to day practice or in looking at dermatoscopic images if learning.

 You look at a lesion and decide on the pattern. Lines take precedence over pseudopods, circles, clods and dots with structureless last. Actually a pattern of vessels comes last but you go with whatever you have! 

Click on the relevant pattern and it will take you to the likely diagnoses. Look then for clues as to  which one matches best. 

Features as Clues.

 When we look at a lesion with a dermatoscope we initially ask "Is it symmetrical or asymmetrical?" and then we look for features which give us a clue to the likeliest diagnosis. These clues we prioritise and then synthesise into two or three likely diagnoses. Sometimes the clues point strongly to only one diagnosis and if benign we go on to the next lesion. However if malignancy comes up as a strong possibility because of asymmetry and clues we excise the lesion. If a weak possibility we may choose to photograph and monitor the lesion in three months. Your tolerance for monitoring usually depends on your experience in the field. If your experience is limited excision is the better course of action especially if you are considering melanoma as a possible diagnosis.

With this in mind use this website to build up your experience in recognising these clues and the potential diagnoses. I will add a section of lesions for you to practice analysing and add some videos discussing the diagnosis.

Download the Tables in the pages area above and print them out to have them easily at hand when looking at lesions. They are set out with the likeliest diagnosis on the left and the others in likely order of probability. 

Use to revise various clinical diagnoses. You can access it in Links opposite.

If you find mistakes or have suggestions for other clues and conditions email me at 

Friday, April 2, 2021

Clues to Melanoma

You can see from this lesion that there are a variety of clues to allow you to diagnose this lesion as a melanoma. Taken together it really can be nothing else. But your next question should then be "How specific are all these clues?" Menzies and others have tried to answer this question by analysing the frequency in large numbers of histologically proven melanomas.
The Sensitivity of a clue means how good is it at picking up a melanoma? 100% sensitivity means the clue is seen in all melanomas. The Specificity means does this clue pick up other pigmented lesions as well? 100% Specificity means it is not seen in other pigmented lesions. So the ideal clue would have 100% sensitivity ie pick up all melanomas and 100% specificity ie not pick up any other pigmented lesions.

Have a look at the image and then click on each of the clues shown in the Archives area opposite for further information on these clues. Basically learn how much weight to put on them. The more clues you have the more likely your diagnosis is to be correct!

Note this image shows the following clues to melanoma
1. Lines radial segmental
2. Peripheral dots
3. Thick lines reticular
4. Structureless blue black and brown areas

It was reported as an ulcerated superficial spreading melanoma, Level 3, 0.93 mm thick. It had 7 mitoses per sq mm of the dermal component of the lesion. The ulceration and the number of mitoses worsen the prognosis.

Click on the clue links above for more details and examples of these clues.

Below is a detailed overview of Clues to a Melanoma taken from 

View this YouTube video on Melanoma, mainly in situ. Click on the arrow and when it starts go to the bottom of the screen and change the 360 resolution to 1080 and then click on the box with the arrows pointing out to enlarge to full screen. These videos are recorded in high definition which makes for great viewing if you have a fast broadband connection. Press ESC on your keyboard to return to normal size.

We can show melanoma with each of the structures mentioned below but most melanomas have a mixture of structures or clues and several colours. With that in mind consider the following examples and also look again at the video on Clues to Melanoma.

Melanoma as thickened lines reticular

Melanoma as lines branched
Melanoma as lines curved

Melanoma as lines parallel ridges

Melanoma as Lines radial peripheral or pseudopods

Melanoma as white lines

Melanoma as grey circles

Melanoma as brown circles
Melanoma as clods

Melanoma as blue clods

Melanoma as grey dots

Melanoma as brown dots

Melanoma as peripheral black dots and clods

Melanoma as polygons

Melanoma as structureless Blue grey or Blue white

Melanoma as pink dot vessels

Melanoma as polymorphic vessels plus dots

Thick lines reticular or branched

This feature is found where the outline of the network is much thicker than that of the rest of the lesion or the surrounding background skin. They represent atypical melanocytes expanding the rete ridges. We see  a lot of reticulated networks because we look at a lot of nevi.  Remember though that some non melanocytic lesions can exhibit a network eg Solar lentigo (with increased melanocytes at the DEJ), reticulated Seb k, Dermatofibroma, Ink spot lentigo and Accessory nipple! 
Non the less a thickened network is a good clue to melanoma within a pigmented lesion when you have a thinner network to compare it to!

Lines radial peripheral or segmental pseudopods

Peripheral lines radial represents nests of growing melanocytes at the edge of a pigmented lesion. A Reed nevus shows the phenomenon best with all the circumference being involved. If only part of the circumference is involved think of a melanoma. 

Peripheral lines radial especially if close inspection shows they are composed of dots is a feature of pigmented IEC (Bowen's disease). 

Peripheral lines radial , segmental meeting at one point is a feature of BCC. (spoke wheel in Menzies terminology).

Ocassionally some seborrhoeic keratoses which are very dark can have peripheral lines radial (or streaks).
Segmental Pseudopods are highly specific for melanoma. The only other condition to consider is a Spitz or Reed nevus.

Look at some of the examples of these features below.