What symptom is indicative of psoriasis when the skin is scratched?

The Auspitz sign is a specific indicator associated with psoriasis that becomes apparent when the skin is scratched. When the lesions characteristic of psoriasis are scraped, small drops of blood surface due to the shedding of the thin layers of skin, leading to pinpoint bleeding. This phenomenon occurs because the psoriatic plaques are highly vascularized and have an overproduction of skin cells that can break apart, exposing the underlying capillaries.

The presence of the Auspitz sign serves as a diagnostic feature, distinguishing psoriasis from other skin conditions. In contrast, while itching, scaling, and redness are common symptoms of psoriasis, they do not have the definitive diagnostic implications of the Auspitz sign. Thus, recognizing the Auspitz sign is crucial for healthcare providers in accurately identifying psoriasis and facilitating appropriate treatment interventions.