To test the hypothesis that pustulosis palmaris et plantaris and psoriatic arthritis (PsA) are two distinct diseases, and that the associated dermatoses are therefore also distinct diseases.
We prospectively performed clinical, radiological, biological, and bone scan investigations in 23 outpatients with pustolotic arthritis and 23 outpatients with PsA, matched by gender, age (+/- one year) and duration of arthritis (+/- two years).
The anterior chest wall, especially the sternocostoclavicular joints, was more frequently involved in pustulotic arthritis than in PsA, both clinically (82% v 43%; p < 0.001) and radiologically (47% v 17%; p < 0.05). Sternocostoclavicular joints generally presented with erosive lesions in PsA, and with large ossifications in pustulotic arthritis. Peripheral joint involvement was mono- or oligoarticular, affecting proximal joints, in pustulotic arthritis (74% v 21%; p < 0.01), and polyarticular, involving small distal joints, in PsA (60% v 0%; p < 10(-4)), in which condition it was also more often erosive (43% v 8%; p < 0.01). The frequency of sacroiliitis and of spine involvement was similar in pustulotic arthritis and PsA. Biology and bone scan did not help distinguish between the two groups.
Pustulotic arthritis and PsA are clinically and radiologically different, therefore pustulosis palmaris et plantaris and psoriasis are most probably distinct dermatological diseases.