Seronegative spondyloarthropathies are a group of diseases characterized by several clinical features such as inflammatory back pain, sacroiliac joint inflammation, and the presence of the HLA B27 antigen, which occurs more frequently than the general population. Non-specific bowel inflammation, skin lesions, particularly psoriasis or uveitis, are also typical in patients or their family members [1]. In many situations, clinical progression of spondyloarthropathies can be assessed by imaging of the sacroiliac joints [2, 3]. SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis), is a rare disease, classified as seronegative spondyloarthropathy due to many typical clinical features for this group of diseases. A large variety of symptoms and atypical clinical picture of SAPHO syndrome causes significant diagnostic difficulties [3, 4]. Presented here is a case report of a 41-year-old male patient with a twenty-year history of the disease. Initially, his disease took the form of chronic, recurrent multifocal osteomyelitis (CRMO), which finally turned into a spondyloarthropathy that met the classification criteria for ankylosing spondylitis.