Diagnosis and Investigation
The diagnosis of psoriasis is made clinically based on the experience of the dermatologist. Skin biopsy is not frequently used to diagnose psoriasis as the typical presentation of psoriasis Vulgaris (plaque psoriasis) is usually easily diagnosed and doesn’t require further investigations. Dermatologists may use characteristic clinical signs of psoriasis as Auspitz sign which involves manual removal of the white scales of psoriasis that will lead to an eruption of small bleeding spots.
The dermatologist may ask about a family history of psoriasis to include or exclude genetic involvement. Rarely, dermatologists may ask you to do lab tests or blood work to rule out other suspected diseases.