Background: Historical studies of myelitis associated with rheumatologic disease may have featured patients with unrecognized aquaporin-4 (AQP4)-IgG seropositive neuromyelitis optica spectrum disorder (NMOSD) or MOG-IgG associated disease (MOGAD). Methods: Cases with rheumatologic disease and myelitis unrelated to multiple sclerosis (MS) seen at Johns Hopkins between 2018-2023 were identified by medical record query and chart review. Descriptive statistics were used to compare AQP4-IgG seropositive to seronegative subjects. Results: Of 234 patients screened, 190 were excluded (144 did not have inflammatory myelopathy, 46 had MS), resulting in a cohort of 44 patient (43 female, mean age 45 years [SD±14]). Twenty patients (45%) had AQP4-IgG seropositive NMOSD, 1 (2%) MOGAD, 20 (45%) other myelitis, and 3 (7%) AQP4-IgG seronegative NMOSD. AQP4-IgG seropositive subjects were more likely to have longitudinally extensive central cord lesions than seronegative patients. Most (n=43; 98%) were tested for serum AQP4-IgG, and 20 (46%) were positive by cell-based assay (CBA) or enzyme-linked immunosorbent assay. Of 24 AQP4-IgG seronegative patients, 8 were tested only by ELISA/unknown assay. Serum MOG-IgG was positive in 2/18 subjects. Conclusions: AQP4-IgG seropositive NMOSD was common in this cohort of patients with rheumatologic disease and myelitis, with the caveat that several seronegative cases were never tested with gold-standard CBA.