AQP4 and synovial sarcoma: For the diagnosis of NMOSD in the absence of AQP4-IgG or in situations where serologic testing is not accessible, more exacting clinical criteria together with additional neuroimaging findings are needed.6 NMOSD risk is higher in patients with AITD (autoimmune thyroid disease), SLE (systemic lupus erythematosus), and SS (systemic sclerosis).