Diascopy is very helpful in diagnosis of:

Ans. d. All of the above (Ref. Rooks textbook of dermatology 7th edition, 5.10)DIASCOPY# Pressing the glass slide or a stiff, clear, colourless piece of plastic onto the skin compresses blood out of small vessels to allow evaluation of other colors.# Useful in- Lupus vulgaris:granulomatous nodules which have transluscent brownish color known as applejelly nodules.- Nevus anemicusiit is a localized area of vasoconstriction, other pigments unaltered. Diascopy of adjacent skin therefore reveals a identical colour to that of the depigmented area.- Diascopy of skin adjacent to vitiligo,in which there is loss of melanin,demonstrates that the vitiligo remains paler.# Application of medium pressure to a spider nevus can compress radiating arterioles and allow visualization of pulsatile flow in the feeding vessel.# In vasculitis lesions are not blanchable.