Monarticular involvement of the manubriosternal joint.

Four females and two males with seronegative monoarthritis of the manubriosternal joint are reported. Two patients had pustulosis palmoplantaris, one psoriasis vulgaris, and one HLA-B27. The arthritis is considered to be a monoarticular manifestation of seronegative spondylarthritis. Two patients had no other diseases or signs. Four patients were followed for a mean of 8.5 years (range 2-16 years) during which time affection of other joints or the spine was not seen.