MRI features of intra-axial histiocytic brain mass lesions

A rare presentation of Rosai-Dorfman disease involving the central nervous system

A 29-year-old gentleman diagnosed with Rosai-Dorfman disease (RDD) on corneal biopsy, 2 years ago, presented with fluctuating left-sided numbness, intermittent slurred speech, and urinary incontinence, progressively worsening over the past three months.

Neuroimaging manifestations of paediatric histiocytoses

Histiocytoses are rare multi-system disorders marked by abnormal histiocyte cell proliferation, affecting children with diverse clinical presentations. Classified into five groups in 2016, including Langerhans-related (L), cutaneous (C), malignant (M), Rosai-Dorfman disease (R) and haemophagocytic lymphohistiocytosis (H), newer entities such as ALK-positive histiocytosis have also emerged, heralding the era of molecular (sub)classification. Common entities include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), Rosai-Dorfman disease (RDD) and haemophagocytic lymphohistiocytosis (HLH). This pictorial essay aids radiologists in recognising and differentiating paediatric histiocytoses based on unique neuroimaging features.

Tumor or not a tumor: Pitfalls and differential diagnosis in neuro-oncology

The majority of intracranial expansive lesions are tumors. However, a wide range of lesions can mimic neoplastic pathology. Differentiating pseudotumoral lesions from brain tumors is crucial to patient management. This article describes the most common intracranial pseudotumors, with a focus on the imaging features that serve as clues to detect pseudotumors.

Rosai–Dorfman disease of the central nervous system: A clinical, radiological, and prognostic study of 12 cases

Background

Rosai–Dorfman disease (RDD) is a rare benign non-Langerhans cell histiocytic proliferative disease. RDD with central nervous system (CNS) involvement (CNS-RDD) is extremely rare. Its etiology is unclear, and there are no consensus recommendations for its treatment. More studies are needed to elucidate the clinical and radiological manifestations and prognosis of CNS-RDD.

Methods

From January 2012 to June 2022, 12 patients with CNS-RDD (intracranial or spinal) were retrospectively evaluated, including collecting clinical data, imaging data, and pathological findings; summarizing imaging characteristics; and conducting follow-up studies on CND-RDD patient treatment and prognosis.

Results

Twelve CNS-RDD patients (nine male and three female patients, aged 12–67 years) were enrolled in this study. Nine patients represented convex and/or skull base RDD (eight with edema, six with lobulation and/or pseudopodium sign, four with multiple intracranial lesions), two patients had parenchymal RDD, and one patient had spinal cord subdural lesions. Symptoms of patients would vary according to the locations of the lesion, including but not limited to headaches, dizziness, seizures, cranial nerve dysfunction, and visual impairment. The immunohistochemistry of RDD showed positive expression of S100 and CD68 but not CD1a. Total resection (n = 7), subtotal resection (n = 3), partial resection (n = 1), and stereotaxic biopsy (n = 1) were achieved, respectively. A combination of chemotherapy plus steroid therapy was performed on two patients (relapsing case and residual lesion) and showed a remarkable effect.

Conclusion

CNS-RDD, as a rare disease, presents a significant diagnostic challenge for clinicians. Solitary CNS-RDD are easily misdiagnosed as meningioma. However, when the MRI imaging of the disease represents dura-based masses with significant edema, homogeneous enhancement, lobulation, and/or pseudopodium sign, we should consider it might be the CNS-RDD. Surgery is an important and effective therapy for CNS-RDD. Steroids and chemotherapy are safe and effective for the postoperative treatment of relapsing cases or residual lesions.

Brainstem lesions: MRI review of standard morphological sequences

MRI signal changes in the brainstem are observed in a multitude of disorders including vascular diseases, neoplastic lesions, degenerative diseases, inflammatory disorders, metabolic diseases, infections, and trauma. In some diseases, brainstem involvement is typical and sometimes isolated, while in other diseases, brainstem lesions are only observed occasionally in the presence of other typical extra-brainstem abnormalities. In this review, we will discuss the MRI characteristics of brainstem lesions observed in different disorders associated with frequent and less frequent brainstem involvement. Identification of the origin of the brainstem lesion depends on the exact localisation of the lesion(s) inside the brainstem, the presence and the characteristics of associated lesions seen outside the brainstem, the signal changes on different MRI sequences, the evolution over time of the radiological abnormalities, the history and clinical state of the patient, and other radiological and non-radiological examinations.

18F-FDG PET/MR Assessment of Pediatric Langerhans Cell Histiocytosis

Introduction

Langerhans cell histiocytosis (LCH) is a histiocytic proliferative disease without a well-understood etiology. The aim of our study is to summarize the imaging features of PET/MR in children with LCH and to explore its diagnostic role in LCH.

Methods

Retrospective analysis was performed of the pretreatment PET/MR imaging data of 15 children with LCH. Comparison of ADC values was done between lesions and normal tissues.

Results

Of the fifteen patients enrolled, five had single-organ or single-system involvement, and ten had multiple-system involvement. Nine patients had varying degrees of bone destruction and increased FDG uptake, whereas thickening and deviation of the pituitary stalk and disappearance of the normal high-signal intensity of T1WI in the neurohypophysis were observed in the pituitary gland in six of them. Splenomegaly with diffuse increased FDG uptake or a normal spleen with increased FDG uptake was found in four cases, liver in three, multiple lymph node enlargement in three, pulmonary lesions in three, and increased metabolism in medullary cavity in two cases. Additionally, two cases involved the skin. Hypermetabolic nodules were detected in muscle in one case, thyroid involvement in one case, and a mediastinal lesion in one case.

Conclusion

PET/MR can show well the distribution of the organs, systems, and lesions involved in LCH and is of considerable significance in the systemic evaluation of LCH.