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General Instructions
For each case, there is a short history along with a clinical and an unmarked dermoscopic image.
Study the unmarked dermoscopic image and try to identify the global and local dermoscopic features.
Make your diagnosis.
Next, turn the page and the dermoscopic image will be presented again, this time marked with all the salient dermoscopic findings.
On the same page you will also find the diagnosis along with a detailed discussion and a few pearls for your review.
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CASE 1 HISTORY
These lesions were symmetrically located on the shins of a 70-year-old woman.
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DERMOSCOPIC CRITERIA
Peripheral white to brownish scaly rim (“white track”) (red arrows)
Double white track at some sites of the peripheral rim (black arrows)
Multiple dotted/pinpoint (black stars) and a few short linear vessels (black circle)
Homogeneous white-yellowish center in 2 lesions (yellow stars)
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DIAGNOSIS:
Disseminated Superficial Actinic Porokeratosis
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The diagnosis is disseminated superficial actinic porokeratosis.
The dermoscopic hallmark of disseminated superficial actinic porokeratosis is white track structures at the periphery.
These structures have also been described as “volcanic craters.”
They may be singular or double.
They reflect the pathognomonic cornoid lamellae of disseminated superficial actinic porokeratosis seen on histopathology.
Red dots, globules, and lines in the center correspond to the vessels of the superficial plexus that become visible as a result of the central atrophy typical of disseminated superficial actinic porokeratosis.
White-yellowish homogeneous areas that correspond to acanthosis are rarely seen.
Depending on the clinical subtype of porokeratosis, different dermoscopic features may be seen.
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CASE 2 HISTORY
A 79-year-old man complained of swelling, redness, and itching on his face for the past year.
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DERMOSCOPIC CRITERIA
Linear vessels arranged in a polygonal network (black circles)
Spiny white threads protruding out of the follicular openings (Demodex “tails”), corresponding to Demodex folliculorum (black arrows)
White-yellowish globules, corresponding to pustules (yellow arrows)
White scales (black star)
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