Dermoscopy case of the month
Dermoscopy and confocal microscopy clues in the diagnosis of psoriasis and porokeratosis

https://doi.org/10.1016/j.jaad.2013.06.008Get rights and content

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Case 1

Multiple red, roundish, small papules with fine superficial scaling suddenly appeared on the lower limbs of a 35-year-old man after a streptococcal infection (Fig 1, A).

Case 2

Numerous roundish, red to pink papules and plaques on the lower limbs of a 79-year-old man persisted after several topical treatments and phototherapy (Fig 1, B).

Dermoscopic appearance

The dermoscopic examination of case 1 revealed dotted vessels over a pinkish background and superficial white scales (Fig 1, C). In case 2, the dermoscopic examination revealed the presence of a peripheral white rim in conjunction with multiple dotted and linear irregular vessels (Fig 1, D).

Confocal microscopy appearance

A reflectance confocal microscopy (RCM) examination of case 1 revealed the presence of parakeratosis at the level of the corneal layer, a regular honeycomb pattern of the spinous layer, and multiple horizontally oriented vessels transversing the dermal papillae (Fig 2, A-C). In case 2, a RCM examination revealed a well demarcated lesion with a distinct hyperrefractile border at the level of the corneal layer, an atypical honeycomb pattern, and architectural disarray (Fig 3, A-C).

Histologic diagnosis

The histologic examination was compatible with plaque psoriasis in case 1 (Fig 2, D) and disseminated superficial actinic porokeratosis (DSAP) in case 2 (Fig 3, D).

Key Message

Several erythematosquamous skin diseases share similar clinical characteristics, and differentiation among them is troublesome. In this context, a dermoscopic examination might be significantly valuable because it might reveal criteria specifically associated with a certain diagnosis. RCM imaging reveals microscopic

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Supported in part by the Italian Ministry of Health (grant RF-2010-2316524).

Conflicts of interest: None declared.

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