CASE REPORT The coexistence of ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis—a postmortem diagnosis Xavier Jordana & Ignasi Galtés & Ana Rita Couto & Luís Gales & Margarida Damas & Manuela Lima & Jácome Bruges-Armas Received: 18 September 2008 / Accepted: 21 November 2008 # Clinical Rheumatology 2008 Abstract A 72-year-old male was diagnosed as having ankylosing spondylitis, mainly according to radiological findings, confirmed as HLA-B27-negative. Postmortem examination of the skeleton raised doubts on the initial diagnosis, since spinal findings pointed out also to diffuse idiopathic skeletal hyperostosis. The authors discuss the differential diagnosis and enhance the postmortem findings which allowed the diagnosis of the two clinical entities in the same patient. Keywords Bone pathology . Joint fusion . Sacroiliitis . Spondyloarthropathy . Syndesmophytes Introduction Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are both complex disorders of unknown etiology involving mainly the axial skeleton with bony proliferation and ankylosis, although both can also display enthesopatic manifestations in the peripheral skeleton. Despite these similarities, AS is a rare chronic inflammatory disorder (0.23–1.8% in Europe) of earlier age onset and with inflammatory manifestations, whereas DISH is usually described as a more common skeletal condition (6–12% of routine autopsies) of elderly patients, with minor clinical manifestations [1–6]. Calcium pyrophosphate dehydrate crystal deposition disease (CPPD CDD) is another condi- tion which involves the axial spine, being frequently undiagnosed. The most know finding is disc calcification, but syndesmophytes and apophyseal joint space narrowing, sclerosis and ankylosis are also frequent findings [7, 8]. The aim of this paper was to report a patient with sacroiliac and spinal disease diagnosed as AS late in life and confirmed as HLA-B27-negative. X-ray findings in the axial skeleton could also allow a DISH diagnosis. The authors had the rare opportunity to examine the skeletal remains years after the patients death. The differential diagnosis is discussed, taking into account the new information obtained. Case report Sacroiliac and spinal disease was identified in a 72-year-old male from Terceira Island (Azores, Portugal) during the European Vertebral Osteoporosis Study radiologic cohort [9]. He and his family members were further interviewed and examined for evidence of arthritis at the Rheumatic Clin Rheumatol DOI 10.1007/s10067-008-1068-9 X. Jordana : M. Lima Research Centre in Natural Resources (CIRN) and Department of Biology, Universidade dos Açores, S. Miguel, Azores, Portugal X. Jordana : I. Galtés Grup de Recerca en Osteobiografia (GROB), Unitat d’Antropologia Biològica, Universitat Autònoma de Barcelona, Barcelona, Spain A. R. Couto : J. Bruges-Armas (*) Serviço Especializado de Epidemiologia e Biologia Molecular (SEEBMO), Hospital Santo Espírito, 9700 Angra do Heroísmo, Terceira, Azores, Portugal e-mail: brugesarmas@gmail.com A. R. Couto : L. Gales : M. Damas : J. Bruges-Armas Institute for Molecular and Cell Biology (IBMC), Universidade do Porto, Porto, Portugal L. Gales : M. Damas Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal