Neuropathologic findings and neurologic symptoms in twenty-three children with hemophagocytic lymphohistiocytosis

HLH as an additional warning sign of inborn errors of immunity beyond familial-HLH in children: a systematic review

Background

Hemophagocytic Lymphohistiocytosis (HLH) is a rare and life-threatening condition characterized by a severe impairment of the immune homeostasis. While Familial-HLH (FHL) is a known cause, the involvement of other Inborn Errors of Immunity (IEI) in pediatric-HLH remains understudied.

Objective

This systematic review aimed to assess the clinical features, triggers, laboratory data, treatment, and outcomes of pediatric HLH patients with IEI other than FHL (IEInotFHL), emphasizing the importance of accurate identification and management.

Methods

A systematic search for studies meeting inclusion criteria was conducted in PubMed, EMBASE, MEDLINE, and Cochrane Central. Quality assessment was performed through JBI criteria.

Results

A comprehensive search yielded 108 records meeting inclusion criteria, involving 178 patients. We identified 46 different IEI according to IUIS 2022 Classification. Combined immunodeficiencies, immune dysregulation disorders, and phagocyte defects were the IEI most frequently associated with HLH. In 75% of cases, HLH preceded the IEI diagnosis, often with an unrecognized history of severe infections. Triggers reflected the specific infection susceptibilities within IEI groups. Liver and central nervous system involvement were less common than in FHL cases. Treatment approaches and outcomes varied, with limited long-term follow-up data, limiting the assessment of therapeutic efficacy across IEI groups.

Conclusion

A comprehensive evaluation encompassing immunological, infectious, and genetic aspects is essential in pediatric-HLH. Relying solely on FHL or EBV susceptibility disorders tests is insufficient, as diverse other IEI can contribute to HLH. Early recognition of HLH as a potential warning sign can guide timely diagnostic investigations and facilitate tailored therapeutic interventions for improved outcomes.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=371425, PROSPERO, CRD42022371425.

Imaging Spectrum of Neurological Manifestations of Hemophagocytic Lymphohistiocytosis in Pediatrics: A Case Series

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon condition, which can result either from a primary genetic abnormality affecting children or secondary to various conditions like malignancy or infection predominantly in adults. HLH is associated with immune dysregulation, resulting in an uncontrolled overproduction and infiltration of lymphocytes and histiocytes. The infiltration predominantly involves liver, spleen, lymph nodes, and central nervous system. Neuroimaging features on magnetic resonance imaging are highly nonspecific and variable. The most typical findings include periventricular white matter hyperintensities and diffuse atrophy. Ring or nodular enhancing or nonenhancing focal parenchymal lesions may be seen. Here, we present three pediatric cases of primary HLH with a wide spectrum of imaging findings involving cerebral and cerebellar cortex, white matter, deep gray matter, and brain stem. The findings in these patients range from small nonenhancing hemorrhagic lesions and enhancing small lesions to ill-defined mass with mass effect and midline shift. Lesions in deep gray matter including thalamus, basal ganglia, and also brain stem in HLH are rarely described in literature. Early diagnosis of HLH and timely management can improve the course of the disease.

Spectrum of neuroradiological manifestations in primary hemophagocytic lymphohistiocytosis: a comparative study of EBV-induced versus non-EBV-induced forms in 75 genetically confirmed pediatric cases

OBJECTIVES

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition affecting young children. It is potentially triggered by Epstein-Barr virus (EBV). This study describes the neuroradiological features observed in 75 children with genetically confirmed primary HLH, comparing EBV-induced with non-EBV-induced HLH forms.

METHODS

Brain MRIs between 2007 and 2021 from 75 children with HLH according to the 2004 Histiocyte Society criteria and with a confirmed HLH-related mutation, were retrospectively reviewed by two pediatric neuroradiologists blinded to EBV status and to mutation status. At diagnosis, 17 children with EBV viremia above a threshold of 1000 copies/mL were included in the EBV-induced HLH group. The remaining 58 patients were included in the non-EBV-induced HLH group.

RESULTS

Of the 75 children initially included, 21 had abnormal MRI (21/75 (28%); 9/17 in the EBV-induced HLH group and 12/58 in the non-EBV-induced HLH group). All patients with abnormal MRI had neurological symptoms. Abnormal MRIs showed white matter lesions; the posterior fossa was affected in all but one case. There was no significant difference between groups regarding the localization or morphology of white matter lesions. The striatum was more frequently affected in the EBV-induced HLH group (8/9 (89%) versus 1/12 (8%), p = 0.00037). All lesions, whether in the white matter or in the basal ganglia, presented increased ADC values on diffusion weighted imaging (DWI).

CONCLUSION

In this study of 75 children with genetically confirmed HLH, only children with neurological signs had abnormal brain MRI. Bilateral striatum involvement suggested an EBV-induced form of HLH.

KEY POINTS

• In children with genetically proven HLH, only those with neurological signs did have brain abnormalities at MRI. • All patients with abnormal brain MRI had multiple white matter lesions with increased ADC values, including in the posterior fossa in almost all cases. • Basal ganglia and in particular the striatum were bilaterally and symmetrically affected in almost all EBV-induced HLH patients, in contrast to the non-EBV-induced HLH patients.

Isolated Sixth Nerve Palsies in a Child With Familial Hemophagocytic Lymphohistiocytosis Type 2

ABSTRACT

A previously healthy 2-year-old boy presented with a left sixth cranial nerve palsy. There was a family history of multiple sclerosis and optic neuritis. Neuroimaging showed multiple foci of T2/FLAIR hyperintense signal abnormality in both cerebral hemispheres and in the brainstem. The initial diagnosis was suspicious for demyelinating disease. However, there was no clinical improvement after a course of corticosteroids, and there was no change in his follow-up MRI. He later developed bilateral sixth nerve palsies, with esotropia addressed with bilateral medial rectus botulinum toxin injections. A brain biopsy was planned. However, his 3-month-old sister was separately admitted for fever and pancytopenia. She had markedly elevated ferritin, D-dimer, triglycerides, sIL-2R, CXCL9, and IL-18 and low fibrinogen. Her bone marrow biopsy showed hemophagocytosis. Genetic testing of both siblings revealed biallelic mutations in the PRF1 locus. The final diagnosis of familial hemophagocytic lymphohistiocytosis Type 2 was made. Both siblings underwent chemotherapy. The boy's sixth nerve palsies and MRI abnormalities resolved. Both siblings then went on to undergo bone marrow transplant.

Presentations and outcomes of familial hemophagocytic lymphohistiocytosis in the pediatric intensive care units (PICUs)

Objectives

We aimed to describe Familial Hemophagocytic Lymphohistiocytosis (F-HLH) patients' clinical features, intensive care courses, and outcomes.

Methods

Multi-center retrospective cohort study of pediatric patients diagnosed with F-HLH from 2015 to 2020 in five tertiary centers in Saudi Arabia. Patients were classified as F-HLH based on their genetic confirmation of known mutation or on their clinical criteria, which include a constellation of abnormalities, early disease onset, recurrent HLH in the absence of other causes, or a family history of HLH.

Results

Fifty-eight patients (28 male, 30 female), with a mean age of 21.0 ± 33.9 months, were included. The most common principal diagnosis was hematological or immune dysfunction (39.7%), followed by cardiovascular dysfunction in 13 (22.4%) patients. Fever was the most common clinical presentation in 27.6%, followed by convulsions (13.8%) and bleeding (13.8%). There were 20 patients (34.5%) who had splenomegaly, and more than 70% of patients had hyperferritinemia >500 mg/dl, hypertriglyceridemia >150 mg/dl and hemophagocytosis in bone marrow biopsy. Compared to deceased patients 18 (31%), survivors had significantly lower PT (p = 041), bilirubin level of <34.2 mmol/L (p = 0.042), higher serum triglyceride level (p = 0.036), and lesser bleeding within the initial 6 h of admission (p = 0.004). Risk factors for mortality included requirements of higher levels of hemodynamic (61.1% vs. 17.5%, p = 0.001) and respiratory (88.9% vs. 37.5%, p < 0.001) support, and positive fungal cultures (p = 0.046).

Conclusions

Familial HLH still represents a challenge in the pediatric critical care setting. Earlier diagnosis and prompt initiation of appropriate treatment could improve F-HLH survival.

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.

Misdiagnosis of adult primary hemophagocytic lymphohistiocytosis as NK/T-cell lymphoma: A case report

We reported a case of a 19-year-old male patient with central nervous system symptoms as the main clinical manifestations, and multiple intracranial and abdominal occupying lesions visualized by imaging examinations, who was initially misdiagnosed as NK/T-cell lymphoma but poorly responsive to the treatment. Finally, he was diagnosed as familial hemophagocytic lymphohistiocytosis type-2 by genome sequencing, perforin test and pedigree study. The patient survived well after allogeneic hematopoietic stem cell transplantation. Central nervous system symptoms could be the main clinical manifestations in patients with primary hemophagocytic lymphohistiocytosis , whose early-stage manifestations of blood system were usually atypical, easily leading to misdiagnosis. In clinical practice, primary hemophagocytic lymphohistiocytosis should be considered in patients with central nervous system symptoms and unknown causes. The combination of rapid immunological function test and genome sequencing contributes to the diagnosis of primary hemophagocytic lymphohistiocytosis.

18F-FDG PET/CT for Identifying the Potential Primary Diseases and Predicting Prognosis of Secondary Hemophagocytic Lymphohistiocytosis in Children

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal illness, which can be divided into primary HLH (pHLH) and secondary HLH (sHLH). pHLH can be driven by genetic defections. Moreover, the sHLH is usually be triggered by malignancy or non-malignancy diseases. Sixty-two newly diagnosed sHLH patients with known etiology and those who underwent ¹⁸F-FDG PET/CT examination from July 2018 to December 2020 were retrospectively analyzed. They were divided into malignancy-associated HLH (M-HLH, n = 13) and non-malignancy-associated HLH (NM-HLH, n = 49). The metabolic parameters of the liver (Li), spleen (Sp), bone marrow (BM), lymph nodes (LN), and their ratios to the liver background (LiBG) and mediastinum (M) were compared between two groups. These metabolic parameters were evaluated for correlation with laboratory parameters and prognostic parameters. We found that the SUV_max-LN/Sp/Li and SUV_mean-Sp in M-HLH were significantly higher than those in NM-HLH (P=0.031, 0.035, 0.016,  and 0.032). The malignant disease should be considered when SUVmax-LN was higher than 4.41 (sensitivity 61.5%, specificity 81.6%). Hypermetabolic lesions in extranodal organs were more likely to occur in M-HLH than in NM-HLH (P=0.011). IFN- γ was positively correlated with SUVmax-BM/Li/Sp and SUVmean-BM/Li/Sp (P < 0.05). Ferritin, sCD25, IL-6, and IL-10 were positively correlated with SUVmax-Sp and SUVmean-Sp (P < 0.05). In Epstein-Barr virus-associated HLH (EBV-HLH), the SUV parameters of bone marrow were significantly correlated with a poor 2-week treatment response, overall survival, and event-free survival (P < 0.05). We conclude that some ¹⁸F-FDG PET/CT metabolic parameters can help identify the etiology of sHLH in children and provide directions for further inspection. The malignant disease should be considered when the SUVmax-LN is higher than 4.41 and hypermetabolic lesions occur in extranodal organs. In EBV-HLH, a higher SUV of bone marrow is associated with a poorer prognosis.

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.

Familial Hemophagocytic Lymphohistiocytosis Secondary to PRF1 Mutation

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome that causes systemic inflammation which can progress to multiorgan failure and death. Symptoms and signs commonly seen in HLH include high fever, hepatosplenomegaly, pancytopenia, and hypertriglyceridemia. This report describes the 8-month clinical course of a 17-year-old male with G6PD deficiency who presented with intermittent high fever of unknown origin for 8 months accompanied by pancytopenia and bilateral lower limb weakness. A pathogenic homozygous missense mutation (c.1081A > T p.(Arg361Trp)) in the PRF1 gene was detected by whole exome sequencing (WES). The brain and the whole spine MRI showed leptomeningeal enhancement at different levels involving both the brain and the spine. Therefore, a diagnosis of familial HLH type 2 with CNS involvement was confirmed. Accordingly, treatment with dexamethasone, cyclosporin, and etoposide in addition to intrathecal methotrexate and hydrocortisone was given. The patient showed a dramatic response with significant neurological improvement of the bilateral lower limb weakness. Genetic analysis has helped the patient's family with appropriate genetic counselling. This case highlights the importance of immediate treatment with immunosuppressants and the high clinical suspicion of physicians regarding HLH in areas where consanguinity is common.

Central nervous system involvement and thrombocytopenia as predictors of mortality in children with hemophagocytic lymphohistiocytosis

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening condition. This study aimed to evaluate treatment outcomes and identify prognostic-related factors in Thai children with HLH.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 76 pediatric patients with HLH who were treated at Ramathibodi Hospital between January 2004 and December 2019. Treatment outcomes were defined as early mortality (death within 30 days after diagnosis) and early treatment response (resolution of all clinical features and normalization of at least one HLH-related laboratory parameter within 4 weeks).

RESULTS

The overall mortality rate was 38% (29/76), with an early mortality rate of 45% (13/29). Malignancy-associated HLH had the highest mortality rate (88%), followed by primary HLH (56%). The predictors of early mortality were central nervous system (CNS) involvement [OR 13 (95%CI 2-83), p = 0.007] and platelet counts <44 × 10⁶/mm³ [OR 8 (95%CI 1.3-49), p = 0.024]. The predictors of early treatment response were no CNS involvement [OR 6.6 (95%CI 1.5-28.8), p = 0.011], platelet counts more than 44 × 10⁶/mm³ [OR 8 (95%CI 2.1-30.9), p = 0.003], and total bilirubin levels <1.8 mg/dL [OR 4 (95%CI 1.1-14.8), p = 0.036]. In the mixed-model analysis, platelet counts in non-survivors increased significantly less than those in survivors, with a mean difference in platelet changes between the two groups of 94.6 × 10⁶/mm³ (p = 0.003).

CONCLUSION

The independent predictors of early mortality in children with HLH were CNS involvement and low baseline platelet counts. A slow rate of platelet increases during the first week after diagnosis was also associated with mortality.

Pathology updates and diagnostic approaches to hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a complex, often under-recognized hyperinflammatory immune dysregulation syndrome arising in a diverse range of clinical scenarios and conditions. The accurate and timely diagnosis of HLH is crucial for patient survival, and usually requires a high level of clinical suspicion. The histologic corollary to clinical HLH - hemophagocytosis - is neither necessary nor sufficient for the diagnosis of HLH, as it may be seen in a variety of reactive conditions and may be absent in true HLH. Nevertheless, the finding of hemophagocytosis in specific clinical situations should prompt consideration of HLH and further testing to exclude the condition. While traditionally described in bone marrow, identification of hemophagocytosis in other tissues, including lymphoid, splenic, liver, or neural tissue, can be an important asset to the overall recognition of HLH. In this review we discuss the underlying pathophysiology and etiologies of HLH, morphologic aspects of hemophagocytosis and its associated histologic findings in different tissues, and give a brief overview of diagnostic criteria and clinical evaluation.

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.

Cytomorphologic Features Found in Cerebrospinal Fluid Specimens of Hemophagocytic Lymphohistiocytosis Patients

OBJECTIVES

Central nervous system involvement is present in 70% of patients with hemophagocytic lymphohistiocytosis (CNS-HLH). CNS-HLH is defined by neurologic deficits, neuroimaging abnormalities, or positive cerebrospinal fluid (CSF) findings. The CSF cytomorphologic spectrum of CNS-HLH, however, has not been well investigated.

METHODS

A retrospective review was performed on 64 CSF specimens from pediatric and adult patients with HLH. Ten patients had clinicoradiologic evidence of CNS involvement.

RESULTS

We identified five CSF cytomorphologic patterns: (1) hemophagocytosis, (2) vacuolated macrophages without evidence of hemophagocytosis, (3) monocytes and/or nonvacuolated macrophages, (4) acellular specimens, and (5) bloody specimens. Patterns 1 and 2 were common in CNS-HLH and rare in patients without CNS involvement. The CSF cytomorphologic patterns did not correlate well with WBC counts or protein concentration.

CONCLUSIONS

Our study offers a comprehensive view of the cytomorphologic features seen in CSF specimens from patients with HLH.

Current status of the diagnosis and treatment of hemophagocytic lymphohistiocytosis in adults

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of defective apoptosis, a disruption of the regulatory pathway that terminates immune and inflammatory responses. Fever, cytopenia, splenomegaly, and/or hemophagocytosis are typical findings of this syndrome. HLH can be induced by genetic disorders (familial) or secondary causes. Familial HLH is rare, while secondary causes in adults include infection, autoimmunity, and malignancy. HLH in adults tends to be confused with or misdiagnosed as sepsis, mainly due to similar clinical manifestations and laboratory findings, which make it difficult to diagnose HLH rapidly and adopt immunosuppressive agents and/or chemotherapy adequately. Treatment of pediatric HLH using HLH-2004 or multi-agent chemotherapy can be applied in adult patients, although the dose and type of drug need to be adjusted. It is highly recommended that allogenic hematopoietic stem cell transplantation should be used in patients who become reactivated or are refractory to the initial treatment as soon as possible to improve survival. Future clinical trials are warranted to determine more suitable treatments for adult patients with HLH.

An autopsy series of an oft-missed ante-mortem diagnosis: hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal syndrome resulting from a hyperactivated immune system. Diverse patient profiles and clinical presentations often result in misdiagnosis. This article describes the varied clinical presentations and autopsy findings in three patients with this entity. The etiopathogenesis of HLH, its disparate and confounding clinical features, the diagnostic criteria, and management principles are also briefly reviewed.

Development of Mast Cell and Eosinophil Hyperplasia and HLH/MAS-Like Disease in NSG-SGM3 Mice Receiving Human CD34+ Hematopoietic Stem Cells or Patient-Derived Leukemia Xenografts

Immunocompromised mouse strains expressing human transgenes are being increasingly used in biomedical research. The genetic modifications in these mice cause various cellular responses, resulting in histologic features unique to each strain. The NSG-SGM3 mouse strain is similar to the commonly used NSG (NOD scid gamma) strain but expresses human transgenes encoding stem cell factor (also known as KIT ligand), granulocyte-macrophage colony-stimulating factor, and interleukin 3. This report describes 3 histopathologic features seen in these mice when they are unmanipulated or after transplantation with human CD34+ hematopoietic stem cells (HSCs), virally transduced hCD34+ HSCs, or a leukemia patient-derived xenograft. The first feature is mast cell hyperplasia: unmanipulated, naïve mice develop periductular pancreatic aggregates of murine mast cells, whereas mice given the aforementioned human cells develop a proliferative infiltrative interstitial pancreatic mast cell hyperplasia but with human mast cells. The second feature is the predisposition of NSG-SGM3 mice given these human cells to develop eosinophil hyperplasia. The third feature, secondary hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS)-like disease, is the most pronounced in both its clinical and histopathologic presentations. As part of this disease, a small number of mice also have histiocytic infiltration of the brain and spinal cord with subsequent neurologic or vestibular signs. The presence of any of these features can confound accurate histopathologic interpretation; therefore, it is important to recognize them as strain characteristics and to differentiate them from what may be experimentally induced in the model being studied.

Atypical neuroimaging characteristics of hemophagocytic lymphohistiocytosis in infants: a case series of hemorrhagic brain lesions in the deep grey matter

Hemophagocytic lymphohistiocytosis (HLH) is a rare multisystem condition associated with uncontrolled overproduction and infiltration of lymphocytes and histiocytes predominantly in liver, lymph nodes, spleen, and central nervous system. Neuroimaging findings on MRI are fairly nonspecific and classically include periventricular white matter signal abnormalities and diffuse atrophy. Focal parenchymal lesions may demonstrate post contrast ring or nodular enhancement and calcification. However, the MR imaging characteristics can be highly variable. Here, we present two cases of HLH in infants with multiple hemorrhagic lesions mostly depicted in both thalami and basal ganglia regions. Thalamic, basal ganglia, and brain stem involvement with hemorrhagic changes in HLH are rarely described in literature. Early diagnosis of HLH may be lifesaving. Awareness of the disease is necessary to investigate its characteristic findings and avoiding a delay in diagnosis.

MRI findings of central nervous system involvement in children with haemophagocytic lymphohistiocytosis: correlation with clinical biochemical tests

AIM

To investigate the brain magnetic resonance imaging (MRI) features of children with haemophagocytic lymphohistiocytosis (HLH) with central nervous system (CNS) involvement, and to investigate the correlation with clinical biochemical tests.

MATERIAL AND METHODS

Clinical and MRI data were collected from 118 children with HLH-CNS between January 2012 and June 2019. Patients were grouped according to their MRI findings, and statistical methods were used to test for correlations between the MRI findings and biochemical variables.

RESULTS

Patients were divided into three groups, including normal appearance (Group 1, 17/118), diffuse parenchymal volume loss (Group 2, 44/118), and brain parenchyma lesions (Group 3, 57/118) containing three subtypes of brain lesions and HLH-CNS complications. Comparing biochemical values among the three groups revealed a significant difference for all values (p<0.05), except for cell counts in the cerebrospinal fluid (CSF). A pairwise comparison further showed significant inter-group differences for most of the variables. Spearman's rank correlation coefficient also demonstrated that CSF cell counts (r=0.193, p=0.036), CSF microprotein content (r=0.379, p<0.001), serum aspartate aminotransferase (AST; r=0.521, p<0.001), serum lactate dehydrogenase (LDH; r=0.514, p<0.001) and activated partial thromboplastin time (APTT; r=0.326, p<0.001) correlated positively with the MRI groups, while platelet count (PLT; r=-0.633, p<0.001) and plasma fibrinogen (FIB; r=-0.258, p=0.005) correlated negatively.

CONCLUSION

Classification of brain MRI findings of HLH-CNS correlates well with the results of several key biochemical tests. Brain MRI is a promising method to elucidate illness severity and clinical outcomes.

Hemophagocytic Lymphohistiocytosis in Patients With Primary Immunodeficiency

Hemophagocytic lymphohistiocytosis (HLH) is characterized by uncontrolled and excessive immune responses with high mortality. We aimed to define mortality-related parameters in HLH secondary to primary immunodeficiency (PID). A total of 28 patients with HLH between the years 2013 and 2017 were enrolled in the study. The patients were evaluated in 2 groups including PID with hypopigmentation (n=7) (Chédiak-Higashi syndrome [CHS] and Griscelli syndrome type 2 [GS2]) and other PIDs (n=21). The median age of the study population was 23 (4.3 to 117.0) months at the time of the diagnosis of HLH. Central nervous system involvement was recorded in 7 (GS2/CHS patients [n=4], other PIDs [n=3], P=0.026), and death was observed in 9 patients (GS2/CHS patients [n=1], other PIDs [n=8], P=0.371). Five patients (3 GS2/CHS and 2 other PID patients) underwent hematopoietic stem cell transplantation. Low serum albumin level was the only variable associated with the mortality and albumin levels less than the cut-off value of 3.07 g/dL increased mortality 5.8 times in patients with HLH secondary to PID. We presented a single-center experience consisting of patients with HLH secondary to PID with a mortality rate of 32.1%. Hypoalbuminemia was the only risk factor to increase the overall mortality rate of HLH.

Neonatal Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is extremely rare in the neonatal period. The incidence of neonatal HLH is not confirmed and may range from 1 in 50,000 to 150,000. The incidence varies based on ethnicity, particularly in populations in which consanguinity is common. HLH is associated with a high fatality rate and poor prognosis, making it important to recognize and diagnose it early. This review will concentrate primarily on the diagnosis and management of neonatal HLH.

Status Epilepticus as a Consequence of Hemophagocytic Lymphohistiocytosis in a Previously Healthy Infant

Hemophagocytic lymphohistiocytosis (HLH) is a rare and fatal entity with an incidence rate of 1.2 cases per million people per year. HLH is explained as a highly destructive inflammatory consequence of rampant hypercytokinemia due to excessive lymphocyte-mediated activation of macrophages and histiocytes. Primary HLH is a product of genetic dysfunction and could be familial (five subtypes), syndromic immunodeficiency, or as a consequence of mutations predisposing a person to Epstein Barr Virus (EBV) infection. With secondary HLH, there is an identifiable cause provoking the inflammatory reaction, whether it is an infection, an autoimmune disease, or malignancy (particularly hematological). As a result of widespread cytokine deposition, systemic manifestations are seen with a variety of manifestations that can vary between cases.

This is a case of a patient who initially presented to the emergency department with fever, altered mentation, and gastroenteritis. Initial investigations showed non-anion gap metabolic acidosis, high white cell count, and deteriorating renal function. Further laboratory tests, bone marrow biopsies, and neurological imaging were conducted throughout the course of admission as the patient further deteriorated systemically. However, it's important to note the abundant neurological manifestations with a worsening level of consciousness and seizures, some of which were categorized as status epilepticus.

Neuroimaging features of CNS histiocytosis syndromes

Histiocytosis syndromes (HS) are group of heterogeneous disorders characterized by abnormal accumulation and infiltration of histiocytes, cells derived from hematopoietic cells of monocyte/macrophage lineage. Overall these disorders are rare. When they do occur they involve many organ systems including the central nervous system (CNS). While imaging findings can provide important clues, diagnosis of this disorder is challenging and definitive diagnosis often necessitates pathologic examination. In this review, we describe imaging features of HS involving the CNS, with the aim to increase our understanding of these disorders. The entities discussed in this review will include: Langerhans cell histiocytosis (LCH), Rosai-Dorfman Disease (RDD), Erdheim Chester Disease (ECD), hemophagocytic lymphohistiocytosis (HLH), and crystal-storing histiocytosis (CSH).

Histopathologic Correlates of Familial Hemophagocytic Lymphohistiocytosis Isolated to the Central Nervous System

Familial hemophagocytic lymphohistiocytosis (HLH) is an immune hyperactivation syndrome caused by mutations in genes associated with cytotoxic T-cell and NK-cell function. While neurological manifestations frequently accompany systemic inflammation at initial presentation, isolated central nervous system (CNS) involvement is rare, and the histological correlates are not well described. We present 3 patients (ages 5, 6, and 7 years) with CNS-isolated familial HLH, who presented with a variety of neurological symptoms and underwent brain biopsies for multifocal enhancing supratentorial and infratentorial lesions. Biopsy slides from all 3 patients revealed similar findings: perivascular lymphocytes, predominantly CD3+ T-cells (CD4>CD8) with occasional intramural infiltration of small vessels; scattered histiocytes without hemophagocytosis; parenchymal and leptomeningeal inflammation varying from mild and focal to severe and sheet-like with associated destructive lesions. There was no evidence of demyelination, neoplasia, or infection. Genetic testing identified compound heterozygous mutations in PRF1 (Patients 1 and 2) and UNC13D (Patient 3), with no evidence of systemic disease except decreased NK-cell function. All 3 patients were treated with hematopoietic stem cell transplantation with marked improvement of symptoms. These findings combined with the poor outcomes associated with delayed diagnosis and lack of aggressive treatment highlight the need to consider HLH in the differential diagnosis of inflammatory brain lesions.

Kawasaki Disease Complicated With Macrophage Activation Syndrome: Case Reports and Literature Review

Macrophage activation syndrome (MAS) is a rare and severe complication of Kawasaki disease (KD). The clinical feature, early diagnosis and treatment options, and prognosis need to be further determined in patients with KD complicated with MAS. In this report, we retrospectively analyzed three KD patients complicated with MAS who were treated in pediatric intensive care units (PICU) and reviewed the relevant literatures. We find that being male, being age over 2 years old, incomplete KD, intravenous immunoglobulin (IVIG) non-responder, or persistent fever greater than 10 days are all highly associated with occurrence of MAS. Additional work-ups should be performed promptly in patient with above predisposing factors to rule out complication of MAS. Patients with KD complicated with MAS are at a higher risk of having coronary artery involvement or aneurysm formation, which can be reversed with timely treatment. Early identification and prompt treatment are key points for improving the prognosis of KD patients complicated with MAS.

Central Nervous System Involvement in Hemophagocytic Lymphohistiocytosis in Adults: A Retrospective Analysis of 96 Patients in a Single Center

Background

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening clinical syndrome. Central nervous system (CNS) involvement is a severe complication, which can lead to rapid disease development and higher morality. However, this has not been given enough attention in adult HLH. Therefore, we carried out this study to analyze the clinical features, laboratory findings, treatment outcomes, and other characteristics of adult HLH with CNS involvement.

Methods

A retrospective analysis of 96 adult patients with HLH combined with CNS involvement between June 2003 and December 2016 was conducted. Clinical features, cerebrospinal fluid (CSF) features, image changes, and therapeutic outcomes were analyzed.

Results

Among the 96 patients, 86 had various CNS symptoms and 33 (38.4%) had already presented symptoms before the HLH diagnosis was confirmed. A total of 59 patients received CSF examinations and showed abnormalities in 23 patients (39.0%). Seventy patients received imaging examinations and the results showed fifty patients with imaging changes (71.4%). Fifty-seven patients received multiple rounds of repeated intrathecal injection therapy and 35 patients improved (61.4%). As for the multiple analyses of effective factors on survival time, the results showed that the effects of combined Epstein-Barr virus (EBV) infection (P = 0.026, Exp(B) = 2.309, 95% confidence interval [CI] [1.108, 4.823) and intrathecal injection therapy (P = 0.013, Exp(B) = 0.422, 95% CI [0.214, 0.831]) on the survival time of the CNS-HLH patients were significant.

Conclusions

Complication with EBV infection is a risk factor, and intrathecal injection is a protective factor. CNS involvement in HLH is not rare, which can result in a poor prognosis. Multiple rounds of repeated intrathecal injection therapy can improve the prognosis of CNS-HLH patients.

The clinical and laboratory evaluation of familial hemophagocytic lymphohistiocytosis and the importance of hepatic and spinal cord involvement: a single center experience

Familial hemophagocytic lymphohistiocytosis is an autosomal recessive, life-threatening condition characterized by defective immune response. A retrospective analysis was performed on 57 patients diagnosed with familial hemophagocytic lymphohistiocytosis at Hacettepe University Pediatric Hematology Department, Ankara, Turkey. Mutation analysis was performed on 37 patients, and of these: 11 had UNC13D, 10 had PRF1 and 3 had STX11 gene mutation. Of these patients, 44% were found to have central nervous system involvement on admission and spinal cord involvement was also seen in 5 patients. Remission was achieved in 24 patients with the treatment, in a median time of 76 days (min-max: 15–705 days). Time to remission was prolonged 3.1 times in patients with a ferritin level 1500 mg/dL or more. When patients were grouped according to age [Group 1 (≤ 2 years), Group 2 (>2 years)]; patients in Group 1 had higher ferritin and aspartate aminotransferase levels but lower fibrinogen levels. The 5-year survival rate was also lower in Group 1. When patients in Group 1 were divided into two sub-groups according to hepatic involvement, the 5-year survival rate of patients who had hepatic involvement was significantly lower than those patients without hepatic involvement (0.7%, 27%, respectively) (P=0.002). The 5-year survival rate of patients who underwent hematopoietic stem cell transplantation was significantly higher than the patients who didn’t (44%, 16%, respectively) (P=0.02). In conclusion, age two years and under, ferritin level above 1500 mg/dL, spinal cord or hepatic involvement should be considered as poor prognostic factors in familial hemophagocytic lymphohistiocytosis.

A patient with severe fever with thrombocytopenia syndrome and hemophagocytic lymphohistiocytosis-associated involvement of the central nervous system

Severe fever with thrombocytopenia syndrome (SFTS), a severe infectious disease caused by novel bunyavirus, SFTS virus (SFTSV), is endemic to China, Korea, and Japan. Most SFTS patients show abnormalities in consciousness. Pathological findings in the central nervous system (CNS) of SFTS patients are not reported. A 53-year-old Japanese man was admitted to Uwajima City Hospital with an 8-day history of fever and diarrhea. Laboratory tests revealed leukopenia, thrombocytopenia, and liver enzyme elevation. He was diagnosed as having severe fever with thrombocytopenia syndrome (SFTS) following detection of the SFTSV genome in his blood. Bone marrow aspiration revealed hemophagocytic lymphohistiocytosis. He suffered progressive CNS disturbance and died on day 13 from onset of first symptoms. The SFTSV genome load in blood and levels of certain cytokines increased over the disease course. Necrotizing lymphadenitis with systemic lymphoid tissues positive for nucleocapsid protein (NP) of SFTSV was revealed by immunohistochemical (IHC) analysis. SFTSV-NP-positive immunoblasts were detected in all organs examined, including the CNS, and in the vascular lumina of each organ. Parenchymal cells of all organs examined were negative for SFTSV-NP on IHC analysis. Microscopic examination of the pons showed focal neuronal cell degeneration with hemosiderin-laden macrophages around extended microvessels with perivascular inflammatory cell infiltration and intravascular fibrin deposition. Autopsy confirmed this patient with SFTS was positive for systemic hemophagocytic lymphohistiocytosis including in the CNS. This patient's neurological abnormalities may have been caused by both functional and organic abnormalities. These novel findings provide important insights into the pathophysiology of SFTS.

[Prognosis of the central nervous system involvement in patients with hemophagocytic lymphohistiocytosis]

Objective: To investigate the characteristics and prognostic factor of central nervous system (CNS) involvement in patients with hemophagocytic lymphohistiocytosis (HLH) . Methods: From January 2006 to October 2015, 152 patients with HLH, 88 patients had CNS involvement, their clinical data were collected, and survival was analyzed using the Kaplan-Meier life table method, univariate and multivariate Cox regression model analyses were applied to identify the risk factors of prognosis. Results: ①57.9% patients complicated with neurological symptoms, cerebrospinal fluid abnormalities were observed in 37.0% patients, 57.5% patients had abnormal neuroradiology. ②36 patients survived well, 3 patients lost to follow-up, 49 dead, 1 survival patient had epilepsy. ③The 3-year overall survival rate of 88 patients was 44%. ④abnormal CSF and unreceived IT bore a significant, independent adverse prognostic value (P<0.05) . Conclusion: CNS involvement in HLH has a high frequency and poor prognosis, few patients remained neurologic sequelae; abnormal CSF related to poor prognosis, positive intrathecal injections could improve the prognosis.

Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis is a life-threatening disorder characterized by unbridled activation of cytotoxic T lymphocytes, natural killer (NK) cells, and macrophages resulting in hypercytokinemia and immune-mediated injury of multiple organ systems. It is seen in both children and adults and is recognized as primary (driven by underlying genetic mutations that abolish critical proteins required for normal function of cytotoxic T cells and NK cells) or secondary (resulting from a malignant, infectious, or autoimmune stimulus without an identifiable underlying genetic trigger). Clinical and laboratory manifestations include fever, splenomegaly, neurologic dysfunction, coagulopathy, liver dysfunction, cytopenias, hypertriglyceridemia, hyperferritinemia, hemophagocytosis, and diminished NK cell activity. It is treated with immune suppressants, etoposide, and allogeneic hematopoietic stem cell transplantation; more than 50% of children who undergo transplant survive, but adults have quite poor outcomes even with aggressive management. Newer agents directed at subduing the uncontrolled immune response in a targeted fashion offer promise in this highly morbid disease.

Central nervous system involvement in adults with haemophagocytic lymphohistiocytosis: a single-center study

Hemophagocytic lymphohistiocytosis (HLH) is a rare multisystem disorder characterized by proliferation and diffuse infiltration multiple organs with histiocytes, including the central nervous system (CNS). Neurological manifestations of HLH have been recognized in different studies with children, but they remain relatively ill-defined in adults with HLH. From March 2008 to October 2014, 289 adult patients with HLH were admitted to our center. Clinical, radiological, and cerebral spinal fluid (CSF) data of the patients with CNS involvement were reviewed, and a retrospective study in our single-center was carried out. CNS involvement was observed in 29 patients (10%) either in their diagnosis process or during disease course. CNS symptoms included disturbance of consciousness, cranial nerve palsies, seizures, headache, limb paralysis, irritability, meningism, and memory loss. CSF analysis was conducted in 17 patients (59%). Among them, 11 patients (65%) were reported as having abnormal CSF. Neuroradiological studies were performed in 25 patients (86%). Among the 13 cases that underwent CT scan, one patient hemorrhaged. Single or multiple hypodense foci were detected in the other 2 patients. Magnetic resonance imaging (MRI) abnormalities were found in 15 patients, including focal lesions in cortical and adjacent subcortical regions with or without variable nodular or ring contrast-enhancement, multiple lesions in white matter, diffuse white matter signal changes, and meningeal enhancement. Basal ganglia, cerebellum, and brainstem lesions were also observed. CNS involvement could also be found in adult patients with HLH, but not as frequent as it was in children. The clinical manifestations could be diversified. By carrying out rigorous CNS examinations, an early diagnosis could be made and it was of the utmost importance for the prevention of further lesions.

Clinically Mild Encephalitis/Encephalopathy With a Reversible Splenial Lesion Accompanied by Epstein-Barr Virus Hemophagocytic Lymphohistiocytosis: A Case Report and Review of the Literature

Central nervous system involvement in hemophagocytic lymphohistiocytosis (HLH) is associated with a poor outcome. For such patients, it is unknown whether more aggressive therapies, such as intrathecal methotrexate or hydrocortisone, are inevitably required. We present a very rare case of 3-year-old Japanese girl who developed mild encephalitis/encephalopathy with a reversible splenial lesion, accompanied by Epstein-Barr virus-associated HLH, and review previous similar reports. Our case and previous reports suggest that mild encephalitis/encephalopathy with a reversible splenial lesion accompanied by Epstein-Barr virus-associated HLH has a relatively good prognosis, even in the absence of intrathecal treatments.

How to Treat Involvement of the Central Nervous System in Hemophagocytic Lymphohistiocytosis?

OPINION STATEMENT

Central nervous system (CNS)-hemophagocytic lymphohistiocytosis (HLH) is not a disease in itself, but it is part of a systemic immune response. The vast majority of patients with CNS-HLH also have systemic HLH and a large number of patients with primary and secondary HLH have CNS involvement. Reactivations within the CNS are frequent during the course of HLH treatment and may occur concomitant with or independent of systemic relapses. It is also important to consider primary HLH as an underlying cause of "unknown CNS inflammation" as these patients may present with only CNS disease. To initiate proper treatment, a correct diagnosis must be made. A careful review of the patient's history and a thorough neurological examination are essential. In addition to the blood tests required to make a diagnosis of HLH, a lumbar puncture with cerebrospinal fluid (CSF) analysis and magnetic resonance imaging (MRI) should always be done in all cases regardless of the presence or absence of neurological signs or symptom. Treatment options for CNS-HLH include, but are not limited to, those commonly used in systemic HLH, including corticosteroids, etoposide, cyclosporine A, alemtuzumab, and ATG. In addition, intrathecal treatment with methotrexate and corticosteroids has become a standard care and is likely to be beneficial. Therapy must be initiated without inappropriate delay to prevent late effects in HLH. An interesting novel approach is an anti-IFN-gamma antibody (NI-0501), which is currently being tested. Hematopoietic stem cell transplantation (HSCT) also represents an important CNS-HLH treatment; patients with primary HLH may benefit from immediate HSCT even if there is active disease at time of transplantation, though care should be taken to monitor CNS inflammation through HSCT and treat if needed. Since CNS-HLH is a condition leading to the most severe late effects of HLH, early expert consultation is recommended.

Hemophagocytic Lymphohistiocytosis: A Diagnostic Conundrum

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive immune activation causing widespread inflammation and tissue destruction leading to multi-organ dysfunction and failure. Making the diagnosis of HLH could be quite challenging due to the broad range of presenting symptoms and their lack of specificity. After ruling out considerations for differential diagnoses, recognizing the most common presenting signs and symptoms of HLH, including neurologic dysfunction, and having a high clinical suspicion for HLH in the setting of inflammatory/demyelinating diseases are important for prompt diagnosis and treatment.

Hemi-meningitis with hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare lymphoproliferative disorder. HLH may occur as a complication of Epstein-Barr virus (EBV), particularly in patients with immunodeficiencies. Herein, we describe a 16-year-old girl with neurological complications associated EBV-induced HLH. Her cerebral magnetic resonance imaging (MRI) showed contrast-enhanced axial T1-weighted images with enhancement of meningeal surface in the right hemisphere that was consistent with right hemi-meningitis. Hydrocephalus, dilated subdural spaces, delayed myelination, edema, diffuse parenchymal atrophy, calcifications, diffuse/patchy white matter abnormalities have all been previously described with HLH. To the best of our knowledge, this is the first case of hemi-meningitis associated with HLH. We suggest that clinicians should consider HLH with vascular disorders when they determine unilateral meningitis on a brain MRI.

Hemophagocytic lymphohistiocytosis associated with Epstein-Barr virus in the central nervous system

Hemophagocytic lymphohistiocytosis (HLH) is a rare immune hyperactivation syndrome which may be primary (genetic) or secondary to various immune-related conditions including infection, immunodeficiency, and malignancies. Rapid diagnosis and treatment are essential because it can be associated with significant morbidity and mortality. Epstein-Barr virus (EBV) is a known infectious cause of acquired HLH, but EBV-associated HLH involving the central nervous system is rare and not well characterized neuropathologically. We report a case of fatal EBV-associated HLH with severe involvement of the central nervous system showing florid hemophagocytosis in the choroid plexus, with extensive neuron loss and gliosis in the cerebrum, cerebellum, and brainstem.

Hemophagocytic lymphohistiocytosis: A rare cause of recurrent encephalopathy

We report an unusual case of recurrent encephalopathy due to acquired hemophagocytic lymphohistiocytosis (HLH) in a patient with propionic acidemia (PA). PA is an inherited metabolic disorder in which patients often present with encephalopathy and pancytopenia during metabolic decompensation. However, these patients may rarely develop HLH with similar presentation. This case illustrates the need to distinguish HLH induced encephalopathy from the one secondary to metabolic decompensation in these patients, as early diagnosis and treatment of HLH improves prognosis. This case also highlights the importance of considering HLH in patients presenting with unexplained encephalopathy, as early diagnosis and treatment is lifesaving in this otherwise lethal condition. To our knowledge this is the first case report of acquired HLH presenting as recurrent encephalopathy followed by complete recovery, in a metabolically stable patient with PA.

Therapeutic effect of JAK1/2 blockade on the manifestations of hemophagocytic lymphohistiocytosis in mice

Treatment with clinical dose of JAK1/2 inhibitor (ruxolitinib) countered manifestations of HLH in 2 cytotoxicity-impaired murine models. JAK1/2 inhibitor therapy in mice is effective on survival, cytopenia, inflammatory syndrome, central nervous system involvement, and liver tissue repair.

A Diagnostic Dilemma: Similarity of Neuroradiological Findings in Central Nervous System Hemophagocytic Lymphohistiocytosis and Aspergillosis

Central nervous system (CNS) involvement in the context of hemophagocytic lymphohistiocytosis (HLH) is not uncommon. Given the immunosuppressive nature of HLH therapy, infectious complications are also seen. We describe a 9-year-old male who developed acute neurological decline secondary to aspergillosis while undergoing HLH therapy. The significant overlap observed in CNS neuroimaging of HLH and aspergillosis and the subtleties that may help differentiate the two are discussed. The importance of obtaining tissue for definitive diagnosis is underscored.

Hemophagocytic Lymphohistiocytosis: Single-Center Series of 12 Cases from Saudi Arabia

Hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially fatal disease that commonly appears in infancy, although it has been reported in adults. Chemoimmunotherapy-based treatments have improved the survival of patients with HLH; however, overall survival is still poor. We retrospectively analyzed the data of 12 HLH patients who were admitted between 2005 and 2014. All patients were Saudi Arabia in origin with a female predominance (75%) and a median age of onset of 9.5 months. The consanguinity rates were significantly high (75%) with a positive family history in 41% of cases. Of the 12 patients, nine were defined as primary HLH patients and three were confirmed to be secondary HLH patients. All patients fulfilled the 2004 diagnostic criteria for HLH and received HLH-2004 treatment. Six of these patients showed a good response to chemotherapy, while the remainder of the patients showed partial or no response to chemotherapy. Five patients in this cohort received stem cell transplant, and these patients are currently in remission. The mortality rate of this cohort is currently 50%. Genetic mutational analysis showed a positive STX11 mutation in five patients and a PRF1 (perforin) mutation in two patients. To the best of our knowledge, this is the first case series of HLH from Saudi Arabia.

Pulmonary Involvement in Patients With Hemophagocytic Lymphohistiocytosis

BACKGROUND

Acquired hemophagocytic lymphohistiocytosis (HLH) is a life-threatening event that usually occurs as a complication of immunodeficiency. Lung involvement in HLH has received little attention. This article describes lung involvement in HLH and assesses whether it affects the prognosis.

METHODS

We retrospectively studied 219 patients with HLH admitted to a national reference center over a 14-year period, including 118 (54%) with lung involvement.

RESULTS

Dyspnea and cough were the most common onset symptoms. Radiographs revealed interstitial infiltrates with centrilobular nodules, ill-defined consolidation, or localized ground-glass opacities. Pleural effusions and mediastinal lymphadenopathies were found in approximately one-half of the patients. One or more causes of lung involvement were documented in 91 of 118 patients (77.1%) and included infection (n = 52), pulmonary edema (n = 34), and malignancies (n = 22 [mostly lymphoma]). HLH-specific treatment combined with treatment of the cause of lung involvement improved respiratory function in only 67 of the 188 patients (56.7%). Hospital mortality was higher in patients with lung involvement (52.5% vs 20%). Infection as the cause of lung involvement was the only determinant of death (56% vs 30%; P = .004).

CONCLUSIONS

Lung involvement is common and of poor prognosis in patients with HLH. Studies should assess whether specific diagnostic and therapeutic strategies are warranted in patients with HLH and lung involvement.

Hemophagocytic lymphohistiocytosis diagnosed by brain biopsy

Hemophagocytic lymphohistiocytosis (HLH) is characterized by fever, splenomegaly, jaundice, and pathologic findings of hemophagocytosis in bone marrow or other tissues such as the lymph nodes and liver. Pleocytosis, or the presence of elevated protein levels in cerebrospinal fluid, could be helpful in diagnosing HLH. However, the pathologic diagnosis of the brain is not included in the diagnostic criteria for this condition. In the present report, we describe the case of a patient diagnosed with HLH, in whom the brain pathology, but not the bone marrow pathology, showed hemophagocytosis. As the diagnosis of HLH is difficult in many cases, a high level of suspicion is required. Moreover, the pathologic diagnosis of organs other than the bone marrow, liver, and lymph nodes may be a useful alternative.