Sunday, August 29, 2010

Other Medical Conditions

Recently there have been a flurry of publications on the dermatoscopic appearances of various inflammatory skin diseases. You can view This Reference to see some of this literature. I will try to illustrate some of these conditions below and do a video on it shortly.

Discoid lupus erythematosus - A characteristic feature is the follicular plugging of keratin in the infundibulum (opening) of the hair follicle. This shows dermatoscopically as white clods with surrounding erythema looking like the surface of a strawberry.

Lichen simplex chronicus  - The dot vessels help here especially the arrangement in rows. A Clear cell acanthoma looks very similar dermatoscopically.

Lichen Planus - Clinically you see violaceous papules at the wrists with fine white lines on the surface. These are called Wickham's striae. Dermatoscopically these show as white crossed lines.

Psoriasis - The most obvious dermatoscopic feature are the red dot vessels corresponding to the thinned supra papillary plates and the tips of the looped papillary vessels being seen end on. It is difficult to differentiate psoriasis from similar dot vessels seen in scc in situ which is also common on the lower legs in sun damaged Australian skin.

Pigmented Purpuric Dermatosis   - The dermatoscopic image of larger red dots corresponding to leaked blood from surface capillaries is very helpful against the background pigmentation from hemosiderin from the iron in the leaked blood.

 Scabies  - The dermatoscope makes visualising scabetic burrows much easier. The scabies mite is seen as a delta wing at one end of the burrow and sometimes scabies faeces are also seen within the burrow. As the burrow is high up in the stratum corneum it is easily seen with the dermatoscope.


Alopecia areata - There are two features the dermatoscope helps you to see. Firstly you should see follicular openings in the bald area. If you dont then it is not alopecia areata but is instead a scarring scalp disease such as discoid lupus, lichen planus, folliculitis decalvans or pseudopelade. The dermatoscope also helps you see exclamation mark hairs at the periphery of the bald area. They are peculiar to alopecia areata.

Head lice - The dermatoscope helps distinguish egg cases from hair casts

Ticks - Sometimes these are so small you need the dermatoscope magnification to see them clearly! Once they have had a good feed of blood they are much easier to see with the naked eye!

Bed Bugs