Polymorphous vessels

I find vessels difficult. Dot vessels represent terminal vessels in the dermal papillae. Below these you have a horizontal superficial and deep dermal plexus of vessels. If the epidermis is thinned and sun damaged(eg on the aged face) you can see the superficial horizontal plexus quite clearly but never completely in focus.
Rapidly growing tumours get their blood supply from this superficial plexus and the vessels become looped as they grow up over the tumour edge. Sometimes over the surface of the tumour they become linear serpentine (linear arborising in Menzies nomenclature) and become sharply focussed. Usually linear serpentine sharply focussed vessels equal a BCC. Coiled or (glomerular) vessels are a feature of Bowen's disease. Vessels with a white halo around them usually mean  a keratinocytic lesion. The vessels in an amelanotic melanoma do not show this keratin halo.
Have a look at some of these annotated lesions below to get a feel for vessels.

Note the variation in vessel type plus the thick white lines and the associated lines reticular. The background pink colour is also a useful clue although Menzies talks about varying shades of pink.
View this case in the Blog