Isolated Intracranial Rosai-Dorfman Disease Mimicking Meningioma: A Case Report.

Rosai-Dorfman Disease (RDD) is a rare lymphoproliferative disease, and the occurrence of isolated intracranial RDD is extremely rare. Most cases of intracranial RDDs present as dural masses showing homogenous enhancement on MRI, which makes it difficult to differentiate these masses from meningiomas before surgery unless massive cervical lymphadenopathy is observed. We herein report a rare case of isolated intracranial RDD in a 65-year-old male. Brain MRI revealed a well-defined enhancing mass-like lesion involving the right frontal convexity and subtle diffusion restriction. However, only a subtle blush was observed on the preoperative cerebral angiogram. Although instances of isolated intracranial RDD are rare, it should be considered as a potential differential diagnosis when a dural mass with hypovascularity is visualized on the cerebral angiogram. Copyrights

INTRODUCTION

Rosai–Dorfman Disease (RDD) is a rare lymphoproliferative disease and is also known as sinus histiocytosis with massive lymphadenopathy. It usually affects young males (1) and most often presents with painless cervical lymphadenopathy, fever, weight loss, and an elevated erythrocyte sedimentation rate (ESR) (2). Although 43% of RDD patients have at least one site of extra-nodal involvement (3), isolated intracranial RDD is extremely rare and accounts for approximately 5% of all extra-nodal RDD cases (4). It usually presents as a dural mass and is frequently misdiagnosed as other extra-axial tumors, such as meningioma. Herein, we report a case of isolated intracranial RDD in a 65-year-old male patient.

CASE REPORT

A 65-year-old-male presented with an episode of generalized tonic-clonic seizures. He had a history of left-sided motor weakness for the last 3 months, since the time of presentation. He was on medication for hypertension and previous angina. At the time of arrival to our hospital, he was conscious and well oriented, with a Glasgow Coma Scale score of 15/15. Neurologic examination revealed decreased motor function on the left side (3/5 on the Grading Motor Strength Grade). There was no lymphadenopathy or organomegaly. Laboratory test results showed no abnormalities, except for elevated ESR levels (69 mm/hr, normal: <20 mm/hr).

A brain CT scan revealed a relatively well-defined, iso-dense, extra-axial mass-like lesion with heterogeneous enhancement at the right frontal convexity (Fig. 1A). The mass was accompanied by extensive perilesional edema, resulting in right lateral ventricular compression. There was no evidence of internal calcifications or adjacent bony hyperostosis. On brain MR imaging, the mass was isointense to hypointense on T2-weighted image and hypointense on T1-weighted image. It showed heterogeneous enhancement (Fig. 1B). Therefore, the preoperative diagnosis was an extra-axial tumor, such as meningioma, solitary fibrous tumor, lymphoma, and metastasis. Cerebral angiography showed a subtle blush (Fig. 1C). Abdominopelvic and chest CT scans were performed to rule out the presence of malignancy and other nodal diseases, and there was no evidence of cervical lymphadenopathy involving the infrahyoid space was seen on chest CT.

Fig. 1

Imaging and pathologic findings of a 65-year-old male with isolated intracranial RDD.

A. Axial CT scan shows an isodense mass-like lesion with irregular margins and heterogeneous enhancement in the right frontal convexity. There are no accompanying bony changes such as bony erosion and hyperostosis.

B. Axial T2- and T1WI images show a hypointense extra-axial mass in the right frontal convexity. Axial and coronal CE-T1WI images show that the mass presents heterogeneous enhancement and irregular margins. The mass is accompanied by extensive perilesional edema, leading to right lateral ventricular compression.

C. On the preoperative right external carotid angiogram, a subtle blush is observed in the right frontoparietal convexity (arrow), and the suspected feeder is the right middle meningeal artery.

D. Photomicroscopic image (× 400, hematoxylin and eosin stain) shows characteristic emperipolesis (black arrowheads) and histiocytic infiltration (blank arrowhead).

CE = contrast-enhanced, RDD = Rosai–Dorfman Disease, T1WI = T1 weighted image, T2WI = T2 weighted image

The patient underwent right frontoparietal craniotomy, and the mass was resected entirely. Histiocytic infiltration and characteristic emperipolesis were identified on carrying out histological analysis (Fig. 1D). Immunohistochemical staining results showed the expression of the proteins CD36 and S100, but no expression of CD1a. Therefore, based on the histological findings, the patient was diagnosed with RDD involving the meninges.

During the latest follow-up examination, the patient was well and on a prescription of antiepileptic medications, although he still had vague left motor weakness. A follow-up MRI scan was done 6 months after the surgery, which revealed that there was no definite residual enhancing lesion and previous peritumoral edema remained with decreased extent.

The need to obtain written informed consent was waived by the Institutional Review Board due to the retrospective nature of the study (IRB No. 2021-07-010).

DISCUSSION

RDD is a rare non-neoplastic lymphoproliferative disorder and frequently presents as bilateral painless massive cervical lymphadenopathy associated with fever, night sweats, fatigue, and weight loss. The etiology of RDD is still uncertain, but viral (Human Herpes virus 6, Epstein-Barr virus) infections, cytokine-mediated migration of monocytes, and mutations disabling the SLC29A3 gene, were suggested as possible causative factors (56).

Extra-nodal involvement is known to take place in 43% of RDD patients (3), with or without associated nodal involvement. Extra-nodal RDD may involve any organ system, but most commonly involves the skin, soft tissues, upper respiratory tract, bones, orbit, nasopharynx, salivary glands, and the central nervous system (4). Primary and isolated intracranial RDD was reported as approximately 5% of the total extra-nodal RDD cases.

Intracranial RDD, unlike systemic RDD, is usually not accompanied by constitutional symptoms such as fever, weight loss, and night sweats. However, intracranial RDD can present variable symptoms depending on the location and size of the lesions. Patients may experience headaches, seizures, or focal neurological deficits due to the mass effect and edemas. The mean age of onset of disease was greater in patients with intracranial RDD than in patients with systemic RDD, presenting massive lymphadenopathy (7). Emperipolesis, the characteristic histopathologic feature of RDD, can be more frequently obscured by prominent fibrosis in intracranial RDD than in the classic nodal presentation (8).

Primary and isolated intracranial RDD are associated with the dura mater and commonly occur in the cerebral convexity, skull base, parasagittal regions, and suprasellar regions, similar to meningiomas (2). On CT scans, these usually appear as well-circumscribed hyperdense lesions with contrast enhancement, and perilesional edema with mass effect (4). MRI scans of RDD usually reveal isointense lesions on T1-weighted images and hypointense lesions on T2-weighted images. RDD generally shows homogenous enhancement after contrast injection (4). Due to these findings, differentiating RDD from meningiomas, Langerhans cell histiocytosis, lymphoproliferative disorders, plasma cell granulomas, granulomatous diseases, and neurofibromatosis is challenging (2). Differentiating intracranial RDD from meningiomas is more frequently difficult due the aforementioned radiologic features. However, meningiomas frequently accompany bony changes, such as hyperostosis and calcifications, while intracranial RDDs rarely accompany these features (9). Furthermore, meningiomas often show hypervascularity on cerebral angiogram, but intracranial RDD show variable findings (10). In addition, only a minor degree of blush was identified on the preoperative angiogram in previous study (11). In our study, accompanying bony changes were not observed on the brain CT scan, and only subtle blush was observed on the preoperative cerebral angiogram. These findings may help in differentiating intracranial RDD from meningioma.

To conclude, we present a rare case of isolated intracranial RDD. RDD is typically accompanied by cervical lymphadenopathy, and intracranial involvement is extremely rare (3). Preoperative differential diagnosis with meningioma is difficult since the isolated intracranial RDD lesion is usually presents as an enhancing mass-like lesion, in relation to the dura mater without cervical lymphadenopathy. However, the absence of accompanying bony changes, such as bony erosion, hyperostosis, calcification, and the absence of angiographic hypervascularity, could help differentiate intracranial RDD from meningioma. The knowledge of these findings could help physicians and radiologic professionals efficiently diagnose RDD and differentiate it from meningiomas.