Sporadic Creutzfeldt-Jakob disease: a rare cause of rapid cognitive decline in a patient with systemic lupus erythematosus.

An immunocompromised patient with non-specific neurological symptoms and signs, along with rapid cognitive decline evolving over three to four weeks, can present a diagnostic challenge. Here we report rapidly progressive dementia in a patient with systemic lupus erythematosus, who was subsequently diagnosed with sporadic Creutzfeldt-Jakob disease (sCJD). This case illustrates the need for prompt investigations to consider an alternative diagnosis where significant history fails to yield an explanation. A diagnosis of sCJD drastically alters the prognosis in a subject with a well-controlled connective tissue disease who is otherwise fit and well.