Osteopoikilosis in a young ankylosing spondylitis patient.

Osteopoikilosis (OPK) is a rare benign congenital genetic-mediated sclerosing skeletal disease, characterized by the formation of osteosclerosis foci. OPK is usually clinically asymptomatic, but some patients (15%~20%) may have arthralgia and synovitis. OPK may be associated with rheumatic diseases and might lead to unreasonable over-examination in real clinical practice. Single cases of the OPK together with ankylosing spondylitis (AS) have been described. Here we present a 33-year-old patient diagnosed with AS coexisting with OPK. In the case considered, the combination of AS and OPK accompanied with a high activity of inflammation, peripheral arthritis, a rapid rate of structural progression in axial skeleton, inefficiency of disease-modifying antirheumatic drugs and nonsteroidal anti-inflammatory drugs, a lack of response to anti interleukin-17 and a good response to a tumor necrosis factor inhibitor golimumab. We describe the important points of differential diagnosis associated with the identification of focal changes in bone tissue, especially neoplastic lesion. Foci revealed had typical localization, so, acquaintance of practicing doctors with such rare cases would minimize unnecessary examinations.