Arthritis plus Psoriasis, a skin disease with white silvery scales, usually on the back of the elbows, front of the knees, very bottom of the back, scalp, & many other places (usually where skin is tight). Psoriasis is common, but having arthritis along with it isn’t.
The arthritis can involve any combination of joints, both small (e.g. hands) and large (like hip or knee). The inflamed joints usually aren’t symmetric on both sides of the body, but sometimes are. Many patients have pains in their tendons and ligaments, not just joints.
Two signs, if present, might clue us in. One is “sausage digit,” a single toe or finger becomes entirely fat & swollen (“digit” in medicine means finger or toe; technical term is “dactylitis”). Another are nail pits, as if someone began to burr tiny holes in the fingernails or toenails.
Blood tests are only useful for ruling out other diseases; there isn’t any for Psoriatic Arthritis itself. There may general abnormalities, like anemia on the CBC, and an elevated Sed Rate (ESR) or CRP. X-rays only help after joint destruction has begun. Basically, rheumatologists make the diagnosis by finding a typical pattern of arthritis in a patient with psoriasis.
Treatment is available. It helps with pain, and prevents joint destruction. Since patients with Psoriatic Arthritis have more risk of heart attacks, due to constant inflammation, the medications are protective in that respect as well.