iatroX Rounds #43
The clues
- 1
A 34-year-old woman presents to her GP with a six-month history of a swollen, painful right index finger and stiffness in her lower back.
- 2
The morning stiffness in her joints typically lasts for over an hour and tends to improve with activity as the day progresses.
- 3
She mentions a ten-year history of a scaly skin rash on her elbows and knees for which she uses topical vitamin D analogues.
- 4
On examination, the entire left third digit is diffusely swollen, and there are multiple small pits and yellowish-orange discolouration of the fingernails.
- 5
Blood tests reveal a raised C-reactive protein but a negative rheumatoid factor and negative anti-cyclic citrullinated peptide antibodies.
- 6
Radiographs of the hands show erosive changes at the distal interphalangeal joints including the characteristic pencil-in-cup appearance.
Psoriatic arthritis is an inflammatory seronegative spondyloarthropathy that occurs in approximately 30 per cent of patients with psoriasis. It often presents with an asymmetrical oligoarthritis but can also cause symmetrical polyarthritis, axial disease, or dactylitis.
- Dactylitis or sausage digits caused by inflammation of the whole digit
- Asymmetrical involvement of the distal interphalangeal joints
- Nail changes including pitting, onycholysis, and oil-drop discolouration
- Radiographic features such as pencil-in-cup deformity and periosteal new bone formation
for education and entertainment. not medical advice.