1 Introduction

A spectrum of pathologies can result in quadriparesis, which include traumatic, infective, inflammatory and neoplastic. RDD is a type lymphoproliferative disorder with lymphadenopathy. RDD can be associated with spinal lesions, which are extradural or intradural extramedullary.^1–4 We present a rare case of intramedullary Rosai Dorfman disease (RDD) in a 24 year old, discuss the clinicoradiological features and review the literature. This is the 7th reported case of intramedullary RDD in English literature.

2 Case report

24-year-old male had two months of insidious onset of difficulty in walking. This gradually worsened and presented with progressive weakness of all four limbs and gradual loss of control of bladder and bowel. There was no history of trauma or fever. On examination he had power of 2/5 in all limbs. The reflexes were brisk bilaterally. His inflammatory markers were unremarkable. Urgent MRI of whole spine was performed to evaluate this further. This showed an expansile T1 hypointense (Fig. 1a) and T2 hyperintense (Fig. 1b) intramedullary long segment lesion spanning from C4-D2. Heterogeneous-low T2 signal areas are seen centrally, with marked perilesional cord oedema. The lesion displayed homogenous post contrast enhancement (Fig. 2). The differential diagnosis of astrocytoma and ependymoma was considered. The patient underwent resection of tumour with a C4-D2 laminectomy. Histological examination revealed lymphocyte aggregates and histiocytes arranged in lobules and sheets (Fig. 3a). Some histiocytes displayed emperopolesis (Fig. 3b), with the overall findings consistent with Rosai-Dorfmann disease (RDD). Post operative MRI showed no residual tumoral tissue with some resolution of symptoms (Fig. 4). MR at 1 year showed significant cord atrophy but no recurrence of RDD. At one year follow up he had some residual weakness due to cord atrophy with power of 3/5 of all four limbs.

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Fig. 1 Sagittal T1(a) and T2(b) demonstrating an expansile T1 hypointense and T2 hyperintense intramedullary long segment lesion spanning from C4-D2.

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Fig. 2 Sagittal (a) and axial(b) T1 fat suppressed post contrast demonstrating homogenous post contrast enhancement.

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Fig. 3 Histological examination revealed lymphocyte aggregates and histiocytes arranged in lobules and sheets (Fig. 3a) and some histiocytes displayed emperopolesis (Fig. 3b).

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Fig. 4 Sagittal T2 shows post surgical changes with cord atrophy but no recurrence of RDD.

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3 Discussion

RDD is also known as sinus histiocytosis with massive lymphadenopathy. As of yet, no single cause has been attributed but given its tendency for recurrence and multi-organ involvement, it is labelled a histiocytic neoplasm.^1,5 Most patients present with painless lymphadenopathy while 40% have extra nodal lesions, typically in the skin, paranasal sinuses and various organ systems.⁵ Up to 1% have isolated/associated spinal lesions, with a predilection for the cervical and thoracic spine.^4,5 Isolated spinal RDD mainly affects young people as in our case, and is usually associated with no lymphadenopathy, making clinical diagnosis very challenging. Most spinal case series describe an extradural, followed by intradural and then intramedullary location with the latter most commonly seen in the thoracic ​> ​cervical spine.^4–6 There are 6 reported cases of intramedullary RDD with all involving the lower cervical and upper thoracic spine.^4,5 4 were male and 2 were female.⁴

Unfortunately, there are no radiological hallmarks of spinal RDD. CT typically shows a homogenous hyperdense with no calcification ​± ​bony erosion.⁷ On MRI, lesions tend to be homogenous with well defined borders on T1 weighted images (WI), additionally post contrast images show homogenous but not avid enhancement. On T2 WI, the lesion tends to be heterogeneous with marked perilesional oedema. The heterogeneous T2 signal maybe helpful in distinguishing RDD from other common intramedullary pathologies such as meningiomas which are usually iso/hyperintense.^8,9 However, this can also be seen in astrocytoma and ependymoma, both common intramedullary cervical spine tumours. The heterogeneous T2 signal is thought to represent free radicals produced during phagocytosis by macrophages.⁸

Although RDD is considered a benign entity, surgical resection is justified in intramedullary lesions for decompression and establishing a histological diagnosis. Where complete excision is not feasible, adjunct therapies such as corticosteroids have been adopted. Moreover, chemotherapy has been used for systemic RDD and radiotherapy for inoperable cases,.⁵ 5 of the 6 cases of isolated intramedullary RDD reported in literature were managed by surgical excision. The remaining case was managed with radiotherapy.⁴ Long term prognosis is related to the number of nodal groups and extranodal systems affected, with isolated spinal RDD usually having a favourable outcome.

Spinal RDD is commonly misdiagnosed as meningioma on imaging but also histology, as they both express S-100 protein histiocytes.^5,7,10 The main differentiating feature specific to RDD is the presence of emperipolesis whereby lymphocytes and other inflammatory cells reside undisturbed within the histiocyte's cytoplasm.¹¹

Cases of isolated intramedullary spinal RDD is increasing in published literature but preoperative diagnosis remains challenging due to similar radiological appearances with other neoplastic and inflammatory processes. Areas of heterogeneous-lowT2 signal in a relatively young patient is suggestive, but histological sampling remains the gold standard in diagnosis.

4 Conclusion

We present a rare case of intramedullary RDD. This should be included in the differential diagnosis of young patient presenting with quadriparesis or paraparesis.

Learning points

•As spectrum of pathologies can cause quadriparesis•Spinal Rosai Dorfman is a rare cause of quadriparesis or paraparesis

Consent

An informed consent of the patient was taken.

Funding

No funding to declare.