Unusual features of neurosarcoidosis: A 18-year retrospective.

BACKGROUND: Neurosarcoidosis (NS) is a challenging diagnosis for clinicians and pathologists. NS most often presents with leptomeningeal involvement where it mimics infectious or neoplastic meningitis, and in up to half of cases, systemic signs of sarcoidosis are lacking. Rare presentations include dural-based mass(es) (mimicking meningioma), hypothalamic/sellar-based lesions (mimicking pituitary adenoma), or as myelopathy (mimicking tumor or neurodegenerative condition). For pathologists, the morphological effects of prior therapy are not well documented. NS as an unsuspected cause of demise today is even less well known.

METHODS: Search of departmental databases and personal files, 2004-2022, for NS cases, with focus on the subset with features of interest to pathologists.

RESULTS: 22 cases were identified (8 M: 14F, 13-66 years), in 11 of which the CNS specimen represented first diagnosis of sarcoidosis. 20 were surgical and 2 were autopsy cases. Focus of the study revolved around 2 surgical cases with NS granulomas intimately admixed with tumor (1 meningoma, 1 gonadotroph pituitary adenoma/pituitary neuroendocrine tumor (PitNET). One surgical and one autopsy case each had decrease in lymphocytes and well-formed granulomas, with increased fibrosis and hemosiderin in post-treatment tissues. We speculate, but cannot prove, that this may be due to prior steroid therapy. Both autopsy cases were women (38, 43-years), both with cauda equina syndrome/ progressive weakness as first presentation, and extensive spinal cord/nerve root sarcoidosis at demise. First diagnosis of NS/sarcoidosis was at autopsy in the 38-year-old.

CONCLUSIONS: Unusual features for pathologists are that NS can co-exist within benign tumors, prior therapy alters histological features, and even in the modern era, may be first diagnosed at autopsy.