Multiple central nervous system lesions on chronic corticosteroid therapy – a diagnostic challenge

Diagnostic challenges often arise when multiple central nervous system (CNS) lesions not accessible to biopsy are present on Magnetic Resonance Imaging (MRI). The differential diagnosis is broad, particularly in the context of exposure to steroids and/or in the setting of immunosuppression. Benign lesions to be considered are demyelinating diseases, sarcoidosis and other granulomatous diseases, and infectious diseases such as toxoplasmosis in immunocompromised patients and tuberculosis. Malignant lesions include CNS lymphoma, glioblastoma multiforme and brain metastases. The authors describe the clinical case of a 75-year-old woman with systemic lupus erythematosus (SLE), chronically medicated with Hydroxychloroquine 400 mg, Deflazacort 9 mg and Azathioprine 25 mg daily, who presented to the hospital with a 5-month history of progressive neurological deficits. It was particularly challenging, because the patient was immunocompromised, had multiple CNS lesions that were not accessible to biopsy and chronic therapy with corticosteroids altered the radiological pattern on brain MRI, masquerading the diagnosis. By writing up this case and review of the literature, further evidence is provided for loss of distinctive histological and radiographic findings of CNS lesions on steroid therapy, with a potential delay in diagnosis and subsequent worse prognosis.