A 59-year-old woman who had been diagnosed with systemic lupus erythematosus (SLE) was admitted to our hospital due to paralysis in all of her limbs. The patient presented with dysarthria, cerebellar ataxia and hypoxia. Magnetic resonance imaging (MRI) revealed vasogenic edema in the brain stem and the cerebellum. She was diagnosed with neuropsychiatric lupus syndrome (NPSLE) and pulmonary arterial hypertension (PAH), and was successfully treated using immunosuppressive therapy. To our knowledge, this is the first reported case of simultaneously developing NPSLE and PAH.