Porokeratosis are morphologically distinct keratinization disorders, characterized clinically by papules or hyperkeratotic plaques surrounded by a linear raised border. Sometimes the border (the most characteristic change in porokeratosis, and practically the definition of diagnosis) is not easily identifiable. We demonstrated a clinical maneuver that facilitated the visualization of this more typical aspect in frame. A wooden tongue depressor was used to gently scratch one of the lesions. This maneuver revealed a desquamative halo in the hyperkeratotic lesion-better identifying the clinical aspect typical of the porokeratosis. The use of scratching may play a fundamental role in the diagnostic suspicion of porokeratosis and should be applied whenever the clinical history suggests this hypothesis as a differential diagnosis.