[Lumbo-sacroiliac hyperostosis with retroperitoneal fibrosis in spondarthritis hyperostotical pustulo-psoriatica--with sternocostoclavicular hyperostosis and superior and inferior venous obstruction syndrome: pathogenetic hypothesis of fibro-osteopathia psoriatica].

We report two cases of retroperitoneal fibrosis which were found in 38 patients with "spondarthritis hyperostotica pustulo-psoriatica" (spond.hyp.p.-p.). Spond.hyp.p.-p. is associated with sternocosto-clavicular hyperostosis and resembles pustulotic arthroosteitis and SAPHO syndrome. However, as dermatologically and osteo-histopathologically documented, it is an enthesiopathic and hyperostotic form of spondarthritis psoriatica. Both cases show a lumbosacroiliac hyperostosis (LSIH) which is a rare analogue to sternocosto-clavicular hyperostosis (SCCH). Facultative paraosseous connective-tissue proliferation results in a new form of retroperitoneal fibrosis with sacroiliac origin. Mediastinal and pelvic masses cause superior and inferior vena caval obstruction syndromes. Because of proven psoriasis in pelvic bone with para-periostal