The Need for a Broad Differential: Intramedullary Neurosarcoidosis Case Report

Background Sarcoidosis, an idiopathic multisystem inammatory disorder, involves the nervous system in as few as 5-15% of cases. We aim to detail how a rare case of intramedullary neurosarcoidosis spinal-cord lesion, present in less than 1% of sarcoidosis cases, presented with features mimicking a neoplasm. Methods Retrospective chart review was performed to obtain pertinent details regarding history and examination, pathological ndings, and treatment course. We report a case of intramedullary sarcoidosis involving the cervical and thoracic spinal cord with syringomyelia, which presented as subacute neck pain, intermittent leg paresthesias, and dicult micturition. Historically, a spinal syrinx with concern for neoplasm has led surgeons to decompress the spinal cord for certain enhancing intramedullary lesions, which is unnecessary for neurosarcoidosis. Immunosuppressant treatment resulted in symptomatic resolution without the need for spinal cord biopsy or syrinx decompression in case.


Introduction
Sarcoidosis, an idiopathic in ammatory disorder, involves the nervous system (neurosarcoidosis) in 5-15% of cases. 1,2 Neurosarcoidosis commonly impacts the hypothalamus, pituitary gland, and cranial nerves. Intramedullary spinal neurosarcoidosis is exceptionally rare, less than 1% of cases. 3 We report a patient with subacute neck pain, intermittent leg paresthesias, and di cult micturition with intramedullary contrast-enhancing lesions and syringomyelia who was diagnosed and treated successfully with immunosuppressants resulting in complete symptomatic and radiographic resolution, highlighting the responsibility of the neurosurgeon to maintain broad differential in management of enhancing spinal cord lesions.

Methods
Retrospective chart review was completed to obtain details for this report. Consent was provided for retrospective chart review to construct the manuscript and for publication of the manuscript.

Case Presentation
History and Examination 31-year-old man with no medical history presented with 3-months of neck pain, intermittent leg paresthesias, and 2 weeks of intermittent di cult micturition. Physical examination revealed positive Hoffman's re exes and mildly diminished pinprick sensation in his lower extremities. Bladder scan revealed >1000mL of retained urine. Contrast-enhanced full-body screening CT revealed moderate bilateral mediastinal lymphadenopathy.

Findings and Treatment Course
After careful assessment of the risk pro le associated with mediastinal lymph node biopsy versus spinal cord biopsy, he underwent endobronchial ultrasound-guided ne-needle aspiration of an enlarged mediastinal lymph node. Histopathological examination revealed non-caseating granulomas with multinucleated giant cells (Fig. 1C,), suggesting intramedullary neurosarcoidosis. Treatment with systemic glucocorticoids, in iximab, and methotrexate resulted in complete resultant neurologic improvement to baseline function within two weeks. Follow-up MRI four months after initiating treatment showed no residual enhancement and complete resolution of the syrinx (Fig. 2).

Discussion
Sarcoidosis, an idiopathic multisystem granulomatous disorder, usually affects lungs, lymph nodes, eyes, and skin; however, it may also affect the nervous system in 5-15% of cases. 4,5 The prototypical patient is a 30-40-year-old African American female. 3 Approximately half of patients present without prior sarcoidosis diagnosis. 6 Neurosarcoidosis is known to mimic neoplasms including ependymoma, astrocytoma, or gliomas; demyelinating diseases including multiple sclerosis or acute disseminated encephalomyelitis; transverse myelitis; and fungal infections. 3,7 Historically, concern for neoplasm has persuaded surgeons to decompress the spinal cord in certain enhancing intramedullary lesions, particularly with accompanying syrinx, resulting in misdiagnosis and inadequate management. 3,8 We describe a rare case of neurosarcoidosis involving contrast-enhancing cervical and thoracic spinal cord lesions with syringomyelia. Findings of cervical and thoracic enhancing masses (Fig. 1A, B) suggested primary malignancy including ependymoma, astrocytoma, or spinal hemangioblastoma. Sarcoidosis, lymphoma, or nonspeci c infectious/in ammatory processes were considered more likely after noting mediastinal and hilar lymphadenopathy, despite negative serum ACE levels. Mediastinal lymph node ne-needle aspiration revealed non-caseating granulomas with multinucleated giant cells (Fig. 1C), consistent with sarcoidosis, and prompt treatment with systemic glucocorticoids, in iximab, and methotrexate resulted in rapid neurologic improvement and resolution of enhancing spinal cord masses and syringomyelia (Fig. 2). A thoughtful approach for enhancing intramedullary spinal cord lesions is the neurosurgeon's responsibility and may obviate the need for decompressive surgery despite the presence of syrinx and/or neurologic de cit. This case report is inherently limited due to retrospective review of clinically relevant patient presentation, treatment, and follow-up. The limitations were minimized through an in-depth review of the patient's medical record.

Conclusion
A rare case of neurosarcoidosis involving contrast-enhancing cervical and thoracic spinal cord lesions with syringomyelia supports that expansile contrast-enhancing intramedullary lesions, most commonly neoplastic, may instead be non-neoplastic etiologies mimicking neoplastic features. Therefore, it is the responsibility of any surgeon to maintain a broad differential diagnosis in the absence of a con rmed pathology.

Declarations i. Funding
This research received no speci c grant from any funding agency in the public, commercial or not-forpro t sectors.

ii. Con icts of interest/Competing interests
The authors have no personal or institutional interest with regards to the authorship and/or publication of this manuscript.
iii. Ethics approval University of Pittsburgh Institutional Review Board authorization: PRO08120394. Consent was provided for chart review to construct the manuscript and for publication of the manuscript. iv. Consent to participate Consent was provided for retrospective chart review to construct the manuscript and for publication of the manuscript. v. Consent for publication Consent was provided for retrospective chart review to construct the manuscript and for publication of the manuscript.
vi. Availability of data and material (data transparency) Not applicable vii. Code availability (software application or custom code) Not applicable viii. Authors' contributions DDL and DT were involved in the design and conception of this manuscript. DDL performed the literature search and acquired the data. DDL and DT compiled the primary manuscript. DDL and DT compiled the gures. DT and PCG critically revised the manuscript. All authors have approved the manuscript as it is written.