Paravertebral ossification in psoriasis and Reiter's disease.

In a retrospective study of psoriatic arthropathy and Reiter's disease, it is shown that paravertebral ossification (PVO), of the type described by Bywaters and Dixon (1965) and other types of non-marginal syndesmophytes (McEwan et al., 1971) may be the sole or major radiological abnormality. This sign is of particular value where the appearances of the sacro-iliac or other joints are normal or equivocal and is at least as significant as the peripheral I.P. joint involvement in the hands, where these conditions are suspected. This radiological sign may precede the typical psoriatic rash.