Systemic Lupus Erythematosus in a patient with Aquaporin 4-Positive Neuromyelitis Optica Spectrum Disorder.

A 27-year-old female presented with a rapidly progressive demyelinating syndrome with anti aquaporin-4 (AQP4) antibodies, initially diagnosed as neuromyelitis optica spectrum disorder (NMOSD). A comprehensive evaluation, prompted by systemic symptoms including chronic polyarthralgia, bicytopenia, and a history of recurrent pregnancy loss, revealed a concurrent diagnosis of systemic lupus erythematosus (SLE), confirmed by positive antinuclear (ANA) and anti-double-stranded DNA (anti-dsDNA) antibodies. The co-occurrence of AQP4-positive NMOSD and SLE is a rare but well-documented clinical phenomenon that presents a unique diagnostic and therapeutic challenge. This also highlights the need for a thorough rheumatological assessment to identify underlying systemic autoimmune diseases in atypical neurological presentations with extra-neurological signs.