From the Research
The Auspitz sign occurs due to the exposure of tiny, dilated blood vessels just below the surface of the skin in psoriatic lesions, which are easily damaged and cause pinpoint bleeding when the scales are gently scraped off. This happens due to the following mechanism:
- In psoriasis, there is rapid cell turnover and inflammation in the skin, as noted in a study on the expression of angiogenic factors in psoriasis vulgaris 1.
- This leads to the formation of thick, silvery scales on top of reddened skin plaques.
- When these scales are gently scraped off, it reveals the tiny, dilated blood vessels just below the surface of the skin.
- These blood vessels are easily damaged, causing pinpoint bleeding. To observe the Auspitz sign:
- Gently scrape the surface of a psoriatic plaque with a glass slide or the edge of a credit card.
- Remove the scales layer by layer until you reach the base of the lesion.
- Look for tiny droplets of blood appearing on the exposed surface. The Auspitz sign is not present in all cases of psoriasis, as noted in a study that found it was present in only 41 of 234 patients with psoriasis 2, and its absence or presence should be considered in conjunction with other clinical findings for diagnosis. Care should be taken when performing this test, as it can cause discomfort to the patient and potentially introduce infection if not done carefully. The most recent study on the topic of psoriasis, which includes information on the clinical and trichoscopic features of scalp psoriasis 3, does not directly address the Auspitz sign, but it highlights the importance of careful examination and consideration of various clinical patterns in diagnosing psoriasis.