Rheumatoid type of psoriatic arthritis.

Psoriatic arthritis can sometimes have a rheumatoid character, manifested especially by symmetrical involvement of the small joints of the hands. This finding was present in 23 out of a total of 150 patients with diagnosed psoriatic arthritis. The association of the rheumatoid joint syndrome and positivity of tests for rheumatoid factors in 4 patients suggest a suspected coincidental association of rheumatoid arthritis and psoriasis. In 2 patients the originally positive tests for rheumatoid factors became negative, simultaneously with the occurrence of sacro-iliitis. The remaining 17 patients had rheumatoid-like joint involvement associated with negative tests for rheumatoid factors. All 17 patients had changes in the spine.