HLA antigens in osteitis condensans ilii and ankylosing spondylitis.

Using a standard microdroplet lymphocyte cytotoxicity test for tissue typing, the distribution of the HLA antigens was determined in 37 female patients; 25 with osteitis condensans ilii (OCI) and 12 with ankylosing spondylitis (AS). Although low back pain was a common feature of OCI, none of these patients exhibited the limitation of spinal involvement, radiological evidence of spondylitis, or progressive clinical course seen in the AS group. Four of the 25 patients with OCI (16 per cent) were B27 positive vs 11 of the 12 patients with AS (92 per cent). These results suggest that OCI is not a variant of AS in women.