Central nervous system-restricted familial hemophagocytic lymphohistiocytosis responds to hematopoietic cell transplantation

Familial hemophagocytic phohistiocytosis induced by PRF1 mutation with neurologic manifestations as the initial clinical presentations: A case report

BACKGROUND

To investigate the clinical characteristics of familial hemophagocytic phohistiocytosis (FHL) induced by PRF1 gene mutation and with central nervous injury as the initial presentation.

CASE PRESENTATION

Herein, we presented 2 cases of a familial hemophagocytic syndrome caused by PRF1 gene mutation in 1 family with central nervous injury as the first symptom and searched relevant literature for clinical analysis of its pathogenic characteristics. Two children from 1 family were included in this study, both of whom had complex heterozygous mutations of C. 1189_1190dupTG (p.H398Afs*23) and C. 394G>A (p.G132R). Literature search further revealed 20 cases of PRF1 gene mutation-induced familial FHL with central nervous injury as the initial presentation. The main neurological symptoms included cranial nerve injury (81.8%), convulsion (77.3%), ataxia (63.6%), encephalopathy (59.1%), and limb paralysis (40.9%). Cranial imaging findings were dominated by the cerebral hemisphere (100%), cerebellar hemisphere (85%), brainstem (55%), and periventricular white matter (40%), and 73.7% of cases had elevated white blood cell count in CSF. Most cases were confirmed by differential diagnosis and gene sequencing, which suggested that C. 673C>T (P.r225W), C. 394G>A (P.G132r), C. 666C>A (p.H222Q), C. 1349C>T (p.T450M), C. 1349C>T (p.T450M), and C. 443C>C (p.A148G) could be focal mutations of this disease.

CONCLUSION

Lesions involving the cerebellum and brainstem in children with ataxia and cranial nerve damage could be indicative of primary FHL; thus, the inherent immune test and gene test should be timely performed to help confirm the diagnosis, guide the treatment, and improve the prognosis.

A Toddler With New Seizures, Progressive White Matter Lesions, and Multifocal Microhemorrhages

A 16-month-old, previously healthy male is hospitalized for new onset seizures. Initial investigation is significant for enterovirus/rhinovirus respiratory infection, abnormal T2 signal predominantly in the white matter and scattered microhemorrhages on brain MRI, transaminitis, and thrombocytopenia. His symptoms initially improve on steroid therapy and he is discharged from the hospital. During the ensuing month with the tapering of the steroids, he develops new motor deficits for which he is rehospitalized. His laboratory investigation on readmission is unremarkable. However, there is significant progression of white matter lesions and microhemorrhages on repeat MRI. While in the hospital, he becomes febrile and has seizure recurrence and worsening neurologic symptoms, including cerebral salt wasting and encephalopathy. Subsequent neuroimaging demonstrates cerebral edema and diffuse brain injury. A high index of suspicion for a rare condition ultimately leads us to perform the specialized testing that confirms the diagnosis. We will discuss the diagnostic challenges that arise from an atypical presentation of an uncommon condition, and from the disease progression that is modified by previous interventions.

Treatment Strategies for Central Nervous System Effects in Primary and Secondary Haemophagocytic Lymphohistiocytosis in Children

Purpose of Review

This review presents an appraisal of current therapeutic options for the treatment of central nervous system haemophagocytic lymphohistiocytosis (CNS-HLH) in the context of systemic disease, as well as when CNS features occur in isolation. We present the reader with a diagnostic approach to CNS-HLH and commonly used treatment protocols. We discuss and evaluate newer treatments on the horizon.

Recent Findings

Mortality is high in patients who do not undergo HSCT, and while larger studies are required to establish benefit in many treatments, a number of new treatments are currently being evaluated. Alemtuzumab is being used as a first-line treatment for CNS-HLH in a phase I/II multicentre prospective clinical trial as an alternative to traditional HLH-1994 and 2004 protocols. It has also been used successfully as a second-line agent for the treatment of isolated CNS-HLH that is refractory to standard treatment. Ruxolitinib and emapalumab are new immunotherapies that block the Janus kinase—Signal Transducer and Activator of Transcription (JAK-STAT) pathway that have shown efficacy in refractory HLH, including for CNS-HLH disease.

Summary

Treatment of CNS-HLH often requires HLH-94 or 2004 protocols followed by haematopoietic stem cell transplantation (HSCT) to maintain remission, although relapse can occur, particularly with reduced intensity conditioning if donor chimerism falls. CNS features have been shown to improve or stabilise following HSCT in CNS-HLH in the context of systemic disease and in isolated CNS-HLH. Encouraging reports of early cohort studies suggest alemtuzumab and the Janus kinase (JAK) inhibitor ruxolitinib offer potential salvage therapy for relapsed and refractory CNS-HLH. Newer immunotherapies such as tocilizumab and natalizumab have been shown to be beneficial in sporadic cases. CNS-HLH due to primary gene defects may be amenable to gene therapy in the future.

Exploring the Intersection of Isolated-CNS Hemophagocytic Lymphohistiocytosis and Pediatric Chronic Lymphocytic Inflammation With Pontine Perivascular Enhancement Responsive to Steroids

CLIPPERS (chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids) is an extremely rare neurologic inflammatory condition. Fewer than 10 pediatric cases have been described.Debate persists as to whether it is a distinct disease or a clinical, radiologic, and histologic phenotype evolving into another disorder. We propose that CLIPPERS may be a clinical manifestation of an underlying state of immune-dysregulation.We describe the case of the youngest known report of CLIPPERS, an 18-month-old infant from Melbourne, Australia. Reviewing the literature for all reported pediatric cases, we identified that robust investigation and whole exome sequencing was underutilized and proposed diagnostic criteria were frequently unmet. Particular focus should be paid to genes known to cause familial hemophagocytic lymphohistiocytosis (HLH), with the CLIPPERS phenotype manifesting as a form of isolated central nervous system (CNS)-HLH in some patients. Curative treatment options such as hematopoietic stem cell transplantation may be appropriate for some patients and should be considered early.

Neurological involvement in secondary hemophagocytic lymphohistiocytosis in children

OBJECTIVES

To describe neurological characteristics and CNS involvement on MRI in secondary hemophagocytic lymphohistiocytosis (sHLH) and differentiate it from primary hemophagocytic lymphohistiocytosis (pHLH) and acute disseminated encephalomyelitis (ADEM).

METHODS

Nine children with sHLH who had neurological symptoms were retrospectively included. Characteristics of brain MRI were compared to those of 15 children with pHLH and neurological involvement and 44 children with ADEM.

RESULTS

Three children (33%) presented with isolated neurological symptoms. Neurological signs occurred within one month following Epstein-Barr virus primary infection or systemic juvenile arthritis exacerbation in 8 patients (89%). Eight children (89%) had MRI lesions. sHLH MRI lesions were distinct of those of pHLH by morphology and signal with more frequent hyposignal intensities on T1-weighted sequences (p = 0.01) and well-defined and less fuzzy lesions (p = 0.03). All patients survived and one patient presented severe motor and cognitive disability.

CONCLUSION

Neurological symptoms of sHLH are non-specific and their outcome is favorable in most of the children. MRI at onset may help to differentiate this condition from pHLH.

Continuous intravenous anakinra for treating severe secondary haemophagocytic lymphohistiocytosis/macrophage activation syndrome in critically ill children

The cytokine storm of secondary haemophagocytic lymphohistiocytosis (sHLH)/macrophage activation syndrome (MAS) can cause life-threatening multiorgan failure. Interleukin-1 (IL-1) receptor blockade with anakinra can be effective in the management of sHLH/MAS. Subcutaneous (SC) dosing regimens are widely described; however, intravenous (IV) dosing is advantageous where time-critical intervention is vital and where SC oedema and/or hypoperfusion limits absorption. We review three critically ill children (aged 9, 11 and 17) with sHLH and rapidly progressive multiorgan dysfunction, successfully treated with continuous IV anakinra infusion. This case series significantly enhances the incipient knowledge regarding the safety and efficacy of IV anakinra for life-threatening sHLH.

Neuroinflammatory Disease as an Isolated Manifestation of Hemophagocytic Lymphohistiocytosis

Isolated neuroinflammatory disease has been described in case reports of familial hemophagocytic lymphohistiocytosis (FHL), but the clinical spectrum of disease manifestations, response to therapy and prognosis remain poorly defined. We combined an international survey with a literature search to identify FHL patients with (i) initial presentation with isolated neurological symptoms; (ii) absence of cytopenia and splenomegaly at presentation; and (iii) systemic HLH features no earlier than 3 months after neurological presentation. Thirty-eight (20 unreported) patients were identified with initial diagnoses including acute demyelinating encephalopathy, leukoencephalopathy, CNS vasculitis, multiple sclerosis, and encephalitis. Median age at presentation was 6.5 years, most commonly with ataxia/gait disturbance (75%) and seizures (53%). Diffuse multifocal white matter changes (79%) and cerebellar involvement (61%) were common MRI findings. CSF cell count and protein were increased in 22/29 and 15/29 patients, respectively. Fourteen patients progressed to systemic inflammatory disease fulfilling HLH-2004 criteria at a mean of 36.9 months after initial neurological presentation. Mutations were detected in PRF1 in 23 patients (61%), RAB27A in 10 (26%), UNC13D in 3 (8%), LYST in 1 (3%), and STXBP2 in 1 (3%) with a mean interval to diagnosis of 28.3 months. Among 19 patients who underwent HSCT, 11 neurologically improved, 4 were stable, one relapsed, and 3 died. Among 14 non-transplanted patients, only 3 improved or had stable disease, one relapsed, and 10 died. Isolated CNS-HLH is a rare and often overlooked cause of inflammatory brain disease. HLH-directed therapy followed by HSCT seems to improve survival and outcome.

Cell Versus Cytokine - Directed Therapies for Hemophagocytic Lymphohistiocytosis (HLH) in Inborn Errors of Immunity

Hemophagocytic lymphohistiocytosis (HLH) is a heterogeneous hyperinflammatory syndrome with different pathways of pathogenesis resulting in similar clinical presentations. It is best defined and understood if presenting in the context of genetic immunodeficiencies associated with defects of lymphocyte cytotoxicity. In these "primary" forms of HLH, cellular and soluble immune effectors are relatively well characterized. While etoposide-based broad cell-directed therapies remain standard of care, more specific therapies targeting these effectors individually are increasingly available. Anti-CD52 as a cell-directed therapy and anti-IFN-gamma, IL-18BP, and JAK-inhibition as cytokine-directed therapies are expected to broaden the therapeutic options, but the precise role of these drugs in first-line and rescue treatment indications remains to be defined. A number of additional inborn errors of immunity are associated with episodes of immune activation fulfilling the clinical criteria of HLH. Impaired pathogen control is a key driver of hyperinflammation in some conditions, while others are characterized by a strong autoinflammatory component. This heterogeneity of disease-driving factors and the variable severity in disease progression in these conditions do not allow a simple adaptation of protocols established for "primary" HLH to HLH in the context of other inborn errors of immunity. Cytokine-directed therapies hold significant promise in these increasingly recognized disorders.

Pediatric CNS-isolated hemophagocytic lymphohistiocytosis

Objective

To highlight a novel, treatable syndrome, we report 4 patients with CNS-isolated inflammation associated with familial hemophagocytic lymphohistiocytosis (FHL) gene mutations (CNS-FHL).

Methods

Retrospective chart review.

Results

Patients with CNS-FHL are characterized by chronic inflammation restricted to the CNS that is not attributable to any previously described neuroinflammatory etiology and have germline mutations in known FHL-associated genes with no signs of systemic inflammation. Hematopoietic stem cell transplantation (HCT) can be well tolerated and effective in achieving or maintaining disease remission in patients with CNS-FHL.

Conclusions

Early and accurate diagnosis followed by treatment with HCT can reduce morbidity and mortality in CNS-FHL, a novel, treatable syndrome.

Classification of evidence

This study provides Class IV evidence that HCT is well tolerated and effective in treating CNS-FHL.