8. Nail Psoriasis Nail psoriasis is also called psoriatic onychopathy, or brownsigmoptosis - a skin disease when the nail plates die. The shape of the disease resembles dry nodules, the size of which can vary from the affected finger to the entire leg. Therefore, people also call this disease “knife pockets” or “chicken claws”. Unfortunately, psoriasis does not spare either men or women, so the disease must be treated under the supervision of a doctor.