Neuroimaging features of CNS histiocytosis syndromes

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.

Erdheim-Chester Disease

Erdheim-Chester disease is a rare non-Langerhans cell histiocytosis. The disease is widely variable in its severity, ranging from incidental findings in asymptomatic patients to a fatal multisystem illness. CNS involvement occurs in up to one-half of patients, most often leading to diabetes insipidus and cerebellar dysfunction. Imaging findings in neurologic Erdheim-Chester disease are often nonspecific, and the disease is commonly mistaken for close mimickers. Nevertheless, there are many imaging manifestations of Erdheim-Chester disease that are highly suggestive of the disease, which an astute radiologist could use to accurately indicate this diagnosis. This article discusses the imaging appearance, histologic features, clinical manifestations, and management of Erdheim-Chester disease.

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.

Aggressive Natural Killer Cell Leukemia in an Adolescent Patient: A Case Report and Literature Review

Aggressive natural killer cell leukemia (ANKL) is a rare malignant tumor, especially uncommon in children. ANKL has very aggressive clinical course and bad prognosis and is usually caused by Epstein-Barr virus infection. ANKL often has clinical manifestations of hemophagocytic lymphohistiocytosis (HLH) and can be easily treated as HLH, which might complicate this aggressive disease. Here we report an ANKL in adolescent whose clinical presentation was highly aggressive and response to L-asparaginase containing chemotherapy was very bad. Early-onset Flow cytometry of peripheral blood and bone marrow help make the diagnosis.

Endothelial cell biomarkers in critically ill COVID-19 patients with encephalitis

COVID-19 is associated with encephalitis in critically ill patients and endothelial dysfunction seems to contribute to this life-threatening complication. Our objective was to determine the hallmark of endothelial activation in COVID-19-related encephalitis. In an observational study in intensive care unit (ICU), we compared vascular biomarkers of critically ill COVID-19 patients with or without encephalitis. To be classified in the encephalitis group, patients had to have new onset of central neurologic symptom, and pathological findings on either brain magnetic resonance imaging (MRI) and/or electroencephalogram (EEG). Among the 32 critically ill COVID-19 consecutive patients, 21 were categorized in the control group and 11 in the encephalitis group. Encephalitis patients had a longer ICU stay than control patients (median length [25th-75th percentile] of 52 [16-79] vs. 20.5 [11-44] days, respectively, p = 0.04). Nine-month overall follow-up mortality reached 21% (7/32 patients), with mortality rates in the encephalitis group and the control group of 27% and 19%, respectively. Encephalitis was associated with significant higher release of soluble endothelial activation markers (sE-selectin, tumor necrosis factor-α (TNF-α), interleukin 6, placental growth factor, and thrombomodulin), but these increases were correlated with TNF-α plasmatic levels. The hypoxia-inducible protein angiopoietin-like 4 (ANGPTL4) was at significantly higher levels in encephalitis patients compared to control patients (p = 0.0099), and in contrary to the other increased factors, was not correlated with TNF-α levels (r = 0.2832, p = 0.1163). Our findings suggest that COVID-19-related encephalitis is a cytokine-associated acute brain dysfunction. ANGPTL4 was the only elevated marker found in encephalitis patients, which was not correlated with systemic inflammation, suggesting that ANGPTL4 might be a relevant factor to predict encephalitis in critically ill COVID-19 patients.

Autoimmune Meningitis and Encephalitis

Meningitis and encephalitis are inflammatory syndromes of the meninges and brain parenchyma, respectively, and may be identified either by finding definitive evidence of inflammation on tissue pathology or by cerebrocpinal fluid (CSF) analysis showing pleocytosis or intrathecal antibody synthesis. Clinicians evaluating undifferentiated meningitis or encephalitis should simultaneously consider autoimmune, infectious, and neoplastic causes, using patient risk factors, clinical syndrome, and diagnostic results including CSF and MRI findings to narrow the differential diagnosis. If an autoimmune cause is favored, an important early diagnostic question is whether a specific neural autoantibody is likely to be identified.

Erdheim-Chester disease: a comprehensive review from the ophthalmologic perspective

Erdheim-Chester disease (ECD) is a rare clonal histiocytic neoplasm with less than 1200 documented cases to date. The disease is life-threatening and difficult to recognize, although increasing awareness as well as the integration of clinical, imaging, pathology information , and genetic studies have led to a recent exponential increase in new reported cases. ECD affects multiple organs and systems, including skeletal, neurologic, and cardiovascular. Pulmonary, retroperitoneal, and cutaneous lesions have also been reported in various combinations. Until the discovery that more than half of ECD patients harbor the BRAF-V600E mutation or other mutations in the mitogen-activated protein kinase (MAPK) and RAS pathways, Interferon-a was the first-line treatment. Nowadays BRAF and MEK-inhibitors targeted therapies are the mainstay of treatment. Ophthalmologic involvement occurs in 25% -30% of ECD cases, usually in the form of orbital involvement presenting with exophthalmos and ophthalmoplegia. Other ophthalmologic manifestations include palpebral xanthelasmas, anterior uveitis and vitritis, optic disk edema, choroidal infiltration, recurrent serous retinal detachment, retinal drusen-like deposits and retinal pigment epithelial changes. ECD patients can also present with ocular symptoms as a result of adverse effects of the treatment regimens. In some cases with smoldering or protean symptoms, the emergence of eye manifestations triggered the diagnosis. Ophthalmologists have to be aware of the disease, recognize the constellation of ECD symptoms, and contribute to the diagnosis, treatment, and follow-up of ECD patients.

Multisystem Langerhans Cell Histiocytosis in an infant

Langerhans cell histiocytosis (LCH) is a rare enigmatic disease that pre-dominantly affects children under 5 years of age. We report an interesting case of a 5 month old female diagnosed with multisystem LCH. Her disease process included osseous, pulmonary, gastrointestinal, cutaneous, hematopoietic and neurologic involvement. This case highlights the varying clinical symptoms, risk factors, pathogenesis, and management of multisystem LCH. This case also emphasizes the role of diagnostic imaging in this multifaceted disease.

Central nervous system involvement in adult-onset relapsing hemophagocytic lymphohistiocytosis responsive to maintenance treatment with anakinra

A 43 year-old male presented with a relapsing and progressive systemic inflammatory disorder with central nervous system (CNS) involvement. After a two years follow up, he was diagnosed with hemophagocytic lymphohistiocytosis (HLH), based on clinical, laboratory and radiological findings. Treatment was started with anakinra, a recombinant humanised interleukin-1 (IL-1) receptor antagonist. Clinical response was good. Laboratory and radiological findings showed no disease activity throughout a five years follow-up period. Several immunosuppressive agents have been used in HLH without any good outcomes. This is the first case report of HLH with CNS involvement responsive to chronic treatment with anakinra.

Imaging Findings in Non-Neoplastic Sinonasal Disease: Review of Imaging Features With Endoscopic Correlates

Non-neoplastic sinonasal disease is common and imaging often plays an important role in establishing the proper diagnosis, guiding clinical management, and evaluating for complications. Both computed tomography and magnetic resonance imaging are commonly employed in the imaging evaluation and it is important to understand the imaging characteristics of the unique types of pathology affecting the sinonasal cavities. This article reviews a variety of infectious, inflammatory, and other non-neoplastic sinonasal pathologies, highlighting imaging features that aid in their differentiation.