Spondyloarthritis is a group of chronic joint diseases that share clinical, pathological and genetic features and is divided into distinct diagnostic entities, including ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease-associated spondyloarthritis, reactive arthritis, juvenile onset and undifferentiated spondyloarthritis. Since the spectrum of spondyloarthritides is wider than the sum of aforementioned disorders suggests, the term “Spondyloarthritis concept” might prove to be appropriate. Here, we present a case in which many features of the spondyloarthritis concept, but also unexpected osteitis in the skull and tibia, emerge during the disease course. A 45-year-old HLA-B27 positive woman with a family history of psoriasis, a former diagnosis of ankylosing spondylitis, reactive arthritis and fulminating acne, was referred to our department with a painful tibial swelling, symmetrical polyarthritis and severe headache. Conventional radiography and bone scintigraphy demonstrated large osteolytic lesions on the left parietal side of the skull and the right anterior tibia. She was treated with surgery and pamidronate. Etanercept treatment was initiated as the arthritis deteriorated and was replaced by infliximab when new onset Crohn’s disease became apparent. This case is the illustration of spondyloarthritis as a disease concept, covering the entire spectrum, from ankylosing spondylitis, urogenital reactive arthritis and psoriatic arthritis to inflammatory bowel disease. Cases like this illustrate that the clinical classification of spondyloarthritis patients into distinct diagnostic entities is bypassing the value of the “concept” and provides support for the new classification criteria that were recently proposed.