Rising levels of BMP in AS patients with spinal fusion and the positive correlation between BMP and spinal radiograph scores indicate that BMP may play a role in the process of spinal ankylosis. Serum levels of BMP may reflect radiographic progression of the spine and hip joints.

Recent Cp infections occur frequently in AS patients and Cp IgM antibody is correlated with active disease. These findings indicate that Cp infections may be a triggering factor for active AS.

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic condition characterized by reversible vasogenic edema on neuroimaging. It is associated with various neurological manifestations, including headaches, vomiting, seizures, visual loss, altered mental status and focal neurological deficits. PRES mainly occurs in the setting of eclampsia, hypertension, uremia, malignancy, transplantation, autoimmune diseases and/or use of immunosuppressive drugs. This syndrome has been described in patients with systemic lupus erythematosus (SLE). PRES is a potentially reversible clinical-radiological entity; however, it can be complicated with vasculopathy, infarction or hemorrhage. Vasculopathy has been demonstrated to be a common finding in patients with SLE. We report the case of a woman with lupus nephritis and PRES whose diffuse vasculopathy was present on initial neuroimaging. Subsequent brain computed tomography scan demonstrated interval development of intraparenchymal hemorrhage and subarachnoid hemorrhage. To our knowledge, this unique brain image pattern has not been reported in SLE patients.

Immunoglobulin G4 (IgG4)-related sclerosing disease is a newly recognized clinicopathological entity characterized by lymphoplasmacytic infiltration and varying degrees of fibrosis in various organs, with abundant IgG4-positive plasma cells in tissues. Patients usually exhibit multisystem involvement and often respond well to steroid and immunosuppressive therapy. However, this disease has been rarely reported in a Chinese population. We herein report a case of IgG4-related sclerosing disease solely presenting with retroperitoneal fibrosis that was effectively treated with systemic steroid therapy. To the best of our knowledge, this is the first reported case of IgG4-related retroperitoneal fibrosis in a Chinese population.