DEJ

The Dermo Epidermal Junction (DEJ) is the site of pathology of a variety of skin diseases. If they cause sufficient epidermal damage or irritation then the disorder may present as a red scaly disease such as Pityriasis lichenoides, or lupus erythematosus or Lichen planus or Polymorphous light disease so the PMs PETAL mnemonic of the red scaly diseases should be considered when thinking about differential diagnoses.

If clefting is occurring at the DEJ or intraepidermal blisters or vesicles are seen then the blistering diseases mnemonic ICI also needs to be considered.

The other diseases with DEJ damage either showing an interface or lichenoid pathology are to be found in the red non scaly mnemonic of CUL DVA EVIE particularly the L for lupus,  DV for drugs and viral or bacterial exanthems plus E for erythema multiforme.