Hemophagocytic lymphohistiocytosis: an update on diagnosis and pathogenesis

Hemophagocytic Lymphohistiocytosis After Initiation of Chemotherapy for Bilateral Adrenal Neuroblastoma

Hemophagocytic lymphohistiocytosis (HLH) is a rare and aggressive syndrome characterized by overactivation of the immune system. Although secondary HLH has been frequently associated with malignancies, this entity is rarely triggered by solid tumors, such as neuroblastomas. Herein, we describe a 14-month-old girl with a late diagnosis of bilateral adrenal neuroblastoma who developed HLH 6 days after the initiation of chemotherapy. On the basis of the large tumoral mass and the time of onset of her symptoms suggestive of HLH, we hypothesize that tumor cell destruction induced by chemotherapy drugs was the trigger to the development of hematophagocytic lymphohistiocytosis syndrome.

Disseminated tuberculosis presenting as hemophagocytic lymphohistiocytosis in an immunocompetent adult patient: a case report

BACKGROUND

Hemophagocytic lymphohistiocytosis is a frequently fatal and likely underdiagnosed disease. It is a rare occurrence in adults and usually secondary to an insult such as viral infections, bacterial infections, autoimmune connective tissue disorders, malignancies and immunocompromised states, in contrast to its childhood counterpart, which is due to a genetic defect but may share some of same genetic etiologies. It is characterized by multisystem inflammation due to unregulated proliferation and infiltration of macrophages and CD8 T cells in the bone marrow, which leads to phagocytosis of red blood cells, platelets, lymphocytes and their precursors.

CASE PRESENTATION

A 40-year-old Sri Lankan woman presented with a high-grade fever of 2 weeks' duration and the initial workup, including a thorough clinical examination, and all the investigations, including a septic screen, were normal. On the 18th day of hospital admission, she was found to have yellowish retinal lesions, which were confirmed as choroid tubercles by the consultant eye surgeon. Two days later she became pancytopenic and a bone marrow biopsy confirmed the diagnosis of hemophagocytic lymphohistiocytosis. She was treated with conventional category-1 antituberculous drugs and an initial 2 weeks with high-dose oral dexamethasone. All the choroid tubercles gradually disappeared and she recovered completely without any complications.

CONCLUSIONS

In an adult patient with hemophagocytic lymphohistiocytosis, it is pivotal to understand the underlying etiology, as it needs extensive immunosuppression. If this patient had been treated with immunosuppressants without antituberculous medications, it would have been lethal with disseminated or central nervous system tuberculosis. So, in areas where tuberculosis is endemic, if no underlying cause is found, it may be worth considering antituberculous treatment for these patients. Re-evaluation with thorough clinical examination is of utmost importance in any patient with pyrexia of unknown origin as well as in any disease with unusual manifestations.

Hemophagocytic lymphohistiocytosis: An unusual complication in disseminated Mycobacterium tuberculosis

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon, potentially fatal, hyperinflammatory syndrome that may rarely complicate the clinical course of disseminated Mycobacterium tuberculosis (MTB). The clinical course of tuberculosis-associated HLH (TB-HLH) has been reported to be unpredictable.

MATERIALS AND METHODS

Here we describe the clinicopathological features, laboratory parameters, management, and outcome data of a patient who satisfied the 2004 diagnostic criteria for HLH secondary to disseminated MTB; we also do a systematic review of the international literature on TB-HLH. The literature review (January 1975-March 2014) found that HLH complicated the clinical course of 63 tuberculosis patients (41 males, 22 females, mean age = 45 ± 23.5 years) with a high mortality rate of 49% (31/63 died). The mean serum ferritin level (n = 44/63) was 5963 ng/mL (range 500-38,539 ng/mL); and a higher proportion (54.2%) of patients had pancytopenia at presentation. On univariate analysis (n = 53/63), age >30 years [hazard ratio (HR): 2.79, 95% confidence interval (CI):1.03-7.56, P = 0.03], presence of comorbidities (HR 4.59, CI: 1.08-19.52, P = 0.04), marked hemophagocytosis in bone marrow (HR: 2.65, CI: 1.16-6.05, P = 0.02), and nonusage/delayed usage of antitubercular therapy (ATT) (HR: 3.44, CI: 1.51-7.87, P = 0.003) were associated with decreased survival, though none of these parameters attained statistical significance (P > 0.05) in multivariate analysis. Usage of corticosteroids and/or immunomodulator drugs (HR 1.00, CI: 0.66-3.22, P = 0.35) did not alter the outcome in these patients.

CONCLUSION

HLH should be considered as a differential diagnosis in patients with tuberculosis who present with cytopenias, organomegaly, and coagulopathy. Strong clinical suspicion and early usage of ATT might be useful in reducing the morbidity and mortality. The utility of immunosuppressive/immunomodulator therapy lacks general concensus among treating physicians, and warrants further studies.

Secondary Hemophagocytic Lymphohistiocytosis in a Patient With Favorable Histology Wilms Tumor

Secondary hemophagocytic lymphohistiocytosis (HLH) is most commonly associated with malignancy, infection, or an underlying autoimmune disorder. Malignancy-associated hemophagocytic syndrome is responsible for most secondary HLH cases, but it has not been well described in children. We present a case of a 4-year-old female with favorable histology of Wilms tumor who developed secondary HLH after unsuccessful resection of the tumor and initiation of chemotherapy.

The challenging diagnosis of haemophagocytic lymphohistiocytosis in an HIV-infected patient

The differential diagnosis of febrile pancytopenia in the setting of HIV infection can be challenging. The authors report a case of a 34-year-old man with advanced HIV infection (TCD4=8 cells/mm(3)) and a 2-month history of fever, weight loss and asthaenia. On observation, he was emaciated, hyperthermic and pale, with a haemorrhagic oropharyngeal lesion, penile violaceous lesions and palpable hepatosplenomegaly. Blood tests showed pancytopenia, hyperferritinaemia and hypertriglyceridaemia; imaging confirmed hepatosplenomegaly and a bone marrow biopsy revealed HIV-associated dyshematopoiesis. Biopsy of the aforementioned lesions displayed Kaposi sarcoma; extensive investigation was negative for other opportunistic infections or lymphoproliferative disease. Despite only a posteriori histological documentation, haemophagocytic lymphohistiocytosis (HLH) was considered; chemotherapy and antiretrovirals were started, with excellent response. There was, however, disease relapse requiring an intensification course, with sustained remission at 18-month follow-up. HLH is a rare disease, with non-specific presentation, requiring a high index of suspicion since treatment delay can be fatal.

Adult-onset central nervous system hemophagocytic lymphohistiocytosis: a case report

Background

Hemophagocytic lymphohistiocytosis (HLH) is a clinical syndrome with both genetic and acquired causes characterized by elevated cytokine levels, hyperinflammation, and overactivation of lymphocytes and macrophages. It is typically a systemic disease with variable degrees of CNS involvement. Cases with predominantly central nervous system (CNS) involvement are very rare, with the vast majority of these occurring in infants and young children. This report documents a case of adult-onset CNS-HLH involving a middle-aged man.

Case presentation

A 55 year-old man developed progressive left hemiparesis and aphasia over the course of several months. Brain MRI showed multifocal, mass-like enhancing lesions with increased susceptibility consistent with blood products. An extensive workup for infectious, autoimmune, and neoplastic etiologies was significant only for a markedly elevated serum ferritin at 1456 ng/mL. Two brain biopsies showed a non-specific inflammatory process. The patient was treated empirically with steroids and plasmapheresis, but he continued to suffer a progressive neurological decline and died one year after onset of neurological symptoms. Autopsy revealed profound histiocytic infiltration, perivascular lymphocytosis, and emperipolesis, compatible with CNS-HLH.

Conclusion

This case report describes an exceedingly rare presentation of an adult patient with CNS predominant HLH. This diagnosis should be considered in the differential diagnosis of adults presenting with progressive brain lesions, even in the absence of typical systemic signs of HLH.

Hemophagocytic Lymphohistiocytosis Complicating Dengue and Plasmodium vivax Coinfection

Hemophagocytic lymphohistiocytosis (HLH) is a rare disorder. Dysfunction of cytotoxic T and natural killer (NK) cells causes uncontrolled activity of lymphocytes and histiocytes which leads to HLH. Infections, malignancies, and autoimmune disorders are associated with development of HLH. Dengue and Plasmodium vivax are rare causes of HLH. We report the first ever case of a young man who developed fatal HLH that complicated Dengue Hemorrhagic Fever (DHF) and Plasmodium vivax infection.

Idiopathic Hemophagocytic Lymphohistiocytosis During Pregnancy Treated with Steroids

Hemophagocytic lymphohistiocytosis (HLH) is a rare and severe clinical syndrome characterized by a dysregulated hyperinflammatory immune response. The diagnosis of HLH during pregnancy is especially challenging due to the rarity of this condition. The highly variable clinical presentation, laboratory findings, and associated diagnoses accompanying this syndrome further complicate the problem. A pronounced hyperferritinemia in the setting of systemic signs and symptoms along with a negative infectious and rheumatological workup should raise suspicions for HLH. While treatment ideally consists of immunosuppressive chemotherapy and hematopoietic stem cell transplant, the potential toxicity to both the pregnant woman and the fetus poses a challenging decision. We report the first case of idiopathic HLH presenting as fever of unknown origin in a pregnant woman successfully treated with steroids.

Multicenter study of combination DEP regimen as a salvage therapy for adult refractory hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a refractory immune disorder with a significant risk of death. Although standard therapy has dramatically improved survival in HLH patients, approximately 30%, especially adults, show no response to current treatment strategies. This prospective study aimed to investigate the efficacy of liposomal doxorubicin treatment combined with etoposide and methylprednisolone (doxorubicin-etoposide-methylprednisolone; DEP) as a salvage therapy for adult refractory HLH. Adult patients who did not achieve at least partial response 2 weeks after initial standard HLH therapy were enrolled in this study between June 2013 and June 2014. Response to salvage therapy was assessed at 2 and 4 weeks after initiation of DEP therapy and patients were followed until death or until November 2014. Sixty-three refractory HLH patients were enrolled, including 29 cases of lymphoma-associated HLH, 22 cases of Epstein-Barr virus-associated HLH, and 4 cases of familial HLH. There were 8 cases with unknown underlying diseases. Seventeen cases (27.0%) achieved complete response and 31 cases (49.2%) achieved partial response. The overall response was 76.2% (48/63). Patients who showed no response to DEP died within 4 weeks after salvage therapy. Twenty-nine of the 48 patients who achieved partial or complete response survived to subsequent chemotherapy, allogenic hematopoietic stem cell transplantation, or splenectomy. Our study suggests that DEP regimen is an effective salvage regimen for adult refractory HLH, which can prolong patient survival as we continue to understand the responsible mechanisms and bridge the gap between HLH and its underlying diseases. This study was registered in the Chinese Clinical Trials Registry Platform (http://www.chictr.org.cn/) as ChiCTR-IPC-14005514.

Hereditary and acquired hemophagocytic lymphohistiocytosis

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare but life-threatening hyperinflammatory/hypercytokinemia syndrome clinicopathologically manifested by fever, hepatosplenomegaly, cytopenias, liver dysfunction, and hemophagocytosis.

METHODS

We searched the medical literature for English-written articles and analyzed data regarding the diagnosis, pathoetiology, prognosis, and management of HLH.

RESULTS

HLH can be subcategorized into primary/genetic (PHLH) or secondary/acquired (SHLH) according to etiology. PHLH, including familial HLH and inherited immune deficiency syndromes, typically occurs in children harboring underlying genetic defects, whereas SHLH frequently manifests in adults and is associated with infection, autoimmunity, immune suppression, or malignancy. The pathogenesis of HLH is still elusive. Its known mechanisms include somatic mutations in gene coding for proteins implicated in the cytotoxic pathways of cytotoxic T or natural killer cells. The impaired ability of these cells to kill target cells leads to an uncontrolled hypercytokinemia and hyperinflammatory process, triggering hemophagocytosis and multiorgan failure. Corticosteroids, chemotherapy, and immunotherapy are the mainstay therapeutic strategies. The consolidation with allogeneic hematopoietic stem cell transplantation is a potentially curative option for PHLH and refractory or relapsed SHLH.

CONCLUSIONS

Understanding of the pathophysiology of HLH has improved in the last decade. The establishment of diagnostic and treatment guidelines for PHLH and SHLH has resulted in earlier diagnoses and the rapid initiation of therapy, both of which are associated with favorable outcomes.

Evaluating the optimal serum ferritin level to identify hemophagocytic lymphohistiocytosis in the critical care setting

Ferritin is known to be involved in numerous physiological roles, such as iron storage, as well as various pathological conditions and in generalized inflammatory states. Hyperferritinemia is also encountered in the setting of hemophagocytic lymphohistiocytosis (HLH). Current diagnostic criteria exist to define HLH based on several clinical and biochemical markers, including the serum ferritin level. In this study, we retrospectively evaluated the value of ferritin >500 ng/mL in diagnosing HLH in 344 consecutive patients admitted to the medical intensive care unit at our hospital. Nine cases of HLH were identified. Comparison of the HLH with the non-HLH group showed that their maximum median serum ferritin level was 25,652 (range 1977-100,727 ng/mL) versus 1180 (503-85,168 ng/mL) (P < 0.001), platelets were 30 (5-92 × 10(3)/μL) versus 113 (0-507 × 10(3)/μL) (P < 0.001), absolute neutrophil counts were 2.56 (0.02-23.7 × 10(3)/μL) versus 7.7 (0.01-82.7 × 10(3)/μL) (P = 0.002), and triglycerides were 255 (156-394 mg/dL) versus 127 (17-624 mg/dL) (P = 0.002), respectively. Using a receiver operating characteristic curve, the optimal maximum serum ferritin level for the diagnosis of HLH was 3951 ng/mL, exceeding the current diagnostic cutoff set forth in the HLH-2004 guidelines. These data suggest that a higher cutoff value of ferritin level may have improved utility in the diagnosis of secondary HLH in the critical care setting.

Hemophagocytic lymphohistiocytosis secondary to infections: a tropical experience!

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal hyper inflammatory condition, if not recognized and treated in time. A high index of suspicion can help identify the condition early. This condition can occur in the primary or secondary form. Secondary HLH or hemophagocytic syndrome (HPS) secondary to infections is an important clinical entity especially in tropical world. In this article, we share our experience with this entity and make an attempt to explore literature about ravenous macrophages which occurs secondary to infections. It is a series of six cases of HLH secondary to infectious disease in our center in a coastal city in South India over last one year with follow up.

Macrophage activation syndrome with acute hepatitis E during tocilizumab treatment for rheumatoid arthritis

Tocilizumab is a humanized antibody against the membrane and soluble receptors for interleukin-6. Tocilizumab is among the disease-modifying antirheumatic drugs (DMARDs) used to treat moderate-to-severe active rheumatoid arthritis (RA) refractory to conventional DMARDs. We report a case of macrophage activation syndrome that complicated acute hepatitis E and started within 24hours after the fourth tocilizumab infusion in a patient with RA.

Human cytomegalovirus and Epstein-Barr virus infection in inflammatory bowel disease: Need for mucosal viral load measurement

AIM: To evaluate the best diagnostic technique and risk factors of the human Cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) infection in inflammatory bowel disease (IBD).

METHODS: A cohort of 40 IBD patients (17 refractory) and 40 controls underwent peripheral blood and endoscopic colonic mucosal sample harvest. Viral infection was assessed by quantitative real-time polymerase chain reaction and immunohistochemistry, and correlations with clinical and endoscopic indexes of activity, and risk factors were investigated.

RESULTS: All refractory patients carried detectable levels of HCMV and/or EBV mucosal load as compared to 13/23 (56.5%) non-refractory and 13/40 (32.5%) controls. The median DNA value was significantly higher in refractory (HCMV 286 and EBV 5.440 copies/10⁵ cells) than in non-refractory (HCMV 0 and EBV 6 copies/10⁵ cells; P < 0.05 and < 0.001) IBD patients and controls (HCMV and EBV 0 copies/10⁵ cells; P < 0.001 for both). Refractory patients showed DNA peak values ≥ 10³ copies/10⁵ cells in diseased mucosa in comparison to non-diseased mucosa (P < 0.0121 for HCMV and < 0.0004 for EBV), while non-refractory patients and controls invariably displayed levels below this threshold, thus allowing us to differentiate viral colitis from mucosal infection. Moreover, the mucosal load positively correlated with the values found in the peripheral blood, whilst no correlation with the number of positive cells at immunohistochemistry was found. Steroid use was identified as a significant risk factor for both HCMV (P = 0.018) and EBV (P = 0.002) colitis. Finally, a course of specific antiviral therapy with ganciclovir was successful in all refractory patients with HCMV colitis, whilst refractory patients with EBV colitis did not show any improvement despite steroid tapering and discontinuation of the other medications.

CONCLUSION: Viral colitis appeared to contribute to mucosal lesions in refractory IBD, and its correct diagnosis and management require quantitative real-time polymerase chain reaction assay of mucosal specimens.

Hemophagocytic Lymphohistiocytosis: an Unusual Complication of Orientia tsutsugamushi Disease (Scrub Typhus)

Background

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon, potentially fatal, hyperinflammatory syndrome that may rarely complicate the clinical course of Orientia tsutsugamushi disease (scrub typhus).

Methods

Here we describe the clinicopathological features, laboratory parameters, management, and outcome of three adult patients (1 female, 2 males) with scrub typhus associated HLH from a tertiary center. A brief and concise review of international literature on the topic was also added.

Results

All three patients satisfied the HLH-2004 diagnostic criteria; one had multi-organ dysfunction with very high ferritin level (>30,000 ng/ml), and all had a dramatic recovery following doxycyclin therapy. Literature review from January 1990 to March 2014 revealed that scrub typhus associated HLH were reported in 21 patients, mostly from the scrub endemic countries of the world. These included 11 females and 10 males with a mean age of 35 years (range; 8 months to 81 years). Fifteen of 17 patients (where data were available) had a favorable outcome following early serological diagnosis and initiation of definitive antibiotic therapy with (N=6) or without (N=9) immunosuppressive/immunomodulator therapy. Mutation analysis for primary HLH was performed in one patient only, and HLH-2004 protocol was used in two patients.

Conclusion

We suggest that HLH should be considered in severe cases of scrub typhus especially if associated with cytopenia (s), liver dysfunction, and coagulation abnormalities. Further studies are required to understand whether an immunosuppressive and/or immunomodulator therapy could be beneficial in those patients who remain unresponsive to definitive antibiotic therapy.

Cervical lymph node diseases in children

The lymph nodes are an essential part of the body’s immune system and as such are affected in many infectious, autoimmune, metabolic and malignant diseases. The cervical lymph nodes are particularly important because they are the first drainage stations for key points of contact with the outside world (mouth/throat/nose/eyes/ears/respiratory system) – a critical aspect especially among children – and can represent an early clinical sign in their exposed position on a child’s slim neck.

Involvement of the lymph nodes in multiple conditions is accompanied by a correspondingly large number of available diagnostic procedures. In the interests of time, patient wellbeing and cost, a careful choice of these must be made to permit appropriate treatment. The basis of diagnostic decisions is a detailed anamnesis and clinical examination. Sonography also plays an important role in differential diagnosis of lymph node swelling in children and is useful in answering one of the critical diagnostic questions: is there a suspicion of malignancy? If so, full dissection of the most conspicuous lymph node may be necessary to obtain histological confirmation.

Diagnosis and treatment of childhood cervical lymph node disorders present the attending pediatric and ENT physicians with some particular challenges. The spectrum of differential diagnoses and the varying degrees of clinical relevance – from banal infections to malignant diseases – demand a clear and considered approach to the child’s individual clinical presentation. Such an approach is described in the following paper.

Visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis in a traveler returning from a pilgrimage to the Camino de Santiago

We report the case of a 73-year-old American traveler who presented with 3 weeks of fatigue, fevers, chills, and pancytopenia. Clinical and laboratory findings were consistent with hemophagocytic lymphohystiocytosis (HLH) and bone marrow biopsy revealed amastigotes consistent with visceral leishmaniasis. The range of endemic visceral leishmaniasis transmission now extends into northern Spain and travelers to this region should use personal protective measures against sand fly exposure.

Hemophagocytic Lymphohistiocytosis (HLH) Associated with T-Cell Lymphomas: Broadening our Differential for Fever of Unknown Origin

Context:

Hemophagocytic lymphohistiocytosis (HLH), due to the excessive activity of histiocytes and lymphocytes, is a rare but aggressive disease that typically occurs in infancy but can be seen in all ages. If left untreated, patients with HLH may live for only a few months and die from multi-organ failure.

Case Report:

We present two cases of HLH diagnosis. Fever, spleen, and hepatic abnormalities were noted in both cases.

Conclusion:

Early diagnosis is the key and these two cases of similar etiology highlight how fever of unknown origin should force us to broaden our differential.

Stored red blood cell transfusions: iron, inflammation, immunity, and infection

Emily Cooley was a highly regarded medical technologist and morphologist. The "Emily Cooley Lectureship and Award" was established to honor her, in particular, and medical technologists, in general. This article reviews some basic concepts about the "life of a red blood cell" (RBC) and uses these to discuss the actual and potential consequences that occur in patients after clearance of transfused refrigerator storage-damaged RBCs by extravascular hemolysis.

Redistribution of iron towards deposits in erythroblastopenic anemia as a consequence of decreased erythroferrone production

Most of the body iron is found within hemoglobin in red cells (the erythron), a smaller amount being distributed in other tissues such as muscles and in deposits. Iron homeostasis is a finely tuned process in which the most important regulators are probably the liver-derived hepcidin which blocks iron absorption and directs iron towards deposits and the recently discovered erythroblast-derived erythroferrone which inhibits hepcidin synthesis and therefore increases availability of iron for hemoglobin synthesis. Hepcidin secretion is increased by inflammatory cytokines and erythroferrone production increases when there is active, expanding erythropoiesis, for example after acute blood loss. We hypothesize that in pathological situations associated with erythroid precursor suppression (erythroblastopenia), anemia is the result of two major mechanisms: (1) direct erythroblast suppression leading to decreased production of red cells and (2) low iron availability due to high hepcidin levels arising as a result of low erythroferrone production. Additionally, infectious episodes and other inflammatory conditions that often complicate the course of these diseases may further promote hepcidin synthesis through increased cytokine production leading to even lower iron availability and a vicious circle of worsening anemia.

Hemophagocytic lymphohistiocytosis: Recent progress in the pathogenesis, diagnosis and treatment

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome that develops as a primary (familial/hereditary) or secondary (non-familial/hereditary) disease characterized in the majority of the cases by hereditary or acquired impaired cytotoxic T-cell (CTL) and natural killer responses. The molecular mechanisms underlying impaired immune homeostasis have been clarified, particularly for primary diseases. Familial HLH (familial hemophagocytic lymphohistiocytosis type 2-5, Chediak-Higashi syndrome, Griscelli syndrome type 2, Hermansky-Pudlak syndrome type 2) develops due to a defect in lytic granule exocytosis, impairment of (signaling lymphocytic activation molecule)-associated protein, which plays a key role in CTL activity [e.g., X-linked lymphoproliferative syndrome (XLP) 1], or impairment of X-linked inhibitor of apoptosis, a potent regulator of lymphocyte homeostasis (e.g., XLP2). The development of primary HLH is often triggered by infections, but not in all. Secondary HLH develops in association with infection, autoimmune diseases/rheumatological conditions and malignancy. The molecular mechanisms involved in secondary HLH cases remain unknown and the pathophysiology is not the same as primary HLH. For either primary or secondary HLH cases, immunosuppressive therapy should be given to control the hypercytokinemia with steroids, cyclosporine A, or intravenous immune globulin, and if primary HLH is diagnosed, immunochemotherapy with a regimen containing etoposide or anti-thymocyte globulin should be started. Thereafter, allogeneic hematopoietic stem-cell transplantation is recommended for primary HLH or secondary refractory disease (especially EBV-HLH).

Hemophagocytic lymphohistiocytosis associated with viral infections: Diagnostic challenge and therapeutic dilemma

Hemophagocytic lymphohistiocytosis is a frequently fatal clinicopathologic syndrome in which an uncontrolled and ineffective immune response leads to severe hyperinflammation. It may occur as either a familial disorder or a sporadic condition in association with a variety of triggers: infections, malignancies, autoimmune diseases, and acquired immune deficiencies. However, the most consistent association is with viral infections, especially Epstein–Barr virus. The main clinical features are fever, liver dysfunction, coagulation abnormalities and pancytopenia. Early diagnosis and treatment are important to reducing mortality, but the diagnosis is difficult because of the rarity of the syndrome and the lack of specificity of the clinical findings. Treatment should be directed toward treating the underlying disease and to suppressing the exaggerated inflammatory response through the use of immunosuppressive agents.

Hemophagocytic lymphohistiocytosis associated with viral infections: Diagnostic challenges and therapeutic dilemmas

Hemophagocytic lymphohistiocytosis is a frequently fatal clinicopathologic syndrome in which an uncontrolled and ineffective immune response leads to severe hyperinflammation. It may occur as either a familial disorder or a sporadic condition in association with a variety of triggers: infections, malignancies, autoimmune diseases, and acquired immune deficiencies. However, the most consistent association is with viral infections, especially Epstein-Barr virus. The main clinical features are fever, liver dysfunction, coagulation abnormalities and pancytopenia. Early diagnosis and treatment are important to reducing mortality, but the diagnosis is difficult because of the rarity of the syndrome and the lack of specificity of the clinical findings. Treatment should be directed towards treating the underlying disease and to suppressing the exaggerated inflammatory response through the use of immunosuppressive agents.

Effects of pristane alone or combined with chloroquine on macrophage activation, oxidative stress, and TH1/TH2 skewness

We investigated the protective role of chloroquine against pristane-induced macrophage activation, oxidative stress, and Th1/Th2 skewness in C57BL/6J mice. Those mice were treated with pristane alone or combined with chloroquine. Hematological and biochemical parameters, macrophage phagocytic function, the oxidant/antioxidant index, cytokine for IFN-γ, TNF-α, IL-4, and IL-6, and the isotypes of IgG2a and IgG1 were determined. And the expression of T-bet/GATA-3 and IL-12/IL-10 mRNA in spleen were analyzed by real-time PCR. We found that pristane treatment for a period of 12 or 24 weeks triggered macrophage activation syndrome, characterized by hemophagocytosis in spleen and peripheral blood, enhanced lipid phagocytosis by peritoneal macrophages in vitro, erythropenia and leucopenia, increased anti-Smith, lactic dehydrogenase, triglyceride, and ferritin, as well as hypercytokinemia of IFN-γ, TNF-α, IL-4, and IL-6. In parallel, a significant increase in lipid peroxidation and a decrease in superoxide dismutase, glutathione, and catalase activity, as well as a skewed Th1/Th2 balance in spleen, were observed. However, chloroquine supplementation showed a remarkable amelioration of these abnormalities. Our data indicate that pristane administration induces macrophage activation, oxidative stress, and Th1/Th2 skewness, which can be attenuated by chloroquine.

Clinical features, genetics, and outcome of pediatric patients with hemophagocytic lymphohistiocytosis in Korea: report of a nationwide survey from Korea Histiocytosis Working Party

Background

We analyzed a nationwide registry of pediatric patients with hemophagocytic lymphohistiocytosis (HLH) in Korea to assess the clinical and genetic features and treatment outcomes in pediatric HLH.

Methods

The Korea Histiocytosis Working Party retrospectively analyzed data on 251 pediatric patients diagnosed with HLH between 1996 and 2011.

Results

In the study cohort, 25 cases were categorized with familial HLH, 64 with presumed secondary HLH, and 162 with unspecified HLH. Of 217 evaluable patients, 91 (42%) had concomitant Epstein–Barr virus infection. Of 238 evaluable patients, central nervous system (CNS) involvement, which was more frequent in the familial group, was evident in 81 cases (34%). Genetic tests revealed a predominant UNC13D mutation with a high incidence of two recurrent splicing mutations (c.118‐308C>T and c.754‐1G>C). The 5‐yr overall survival rate was 68% (38% in the familial group and 81% in the presumed secondary group). The 5‐yr overall survival rate among 32 patients who underwent allogeneic hematopoietic stem cell transplantation was 64%. In multivariate analysis, a younger age at diagnosis, severe transaminasemia, and a coagulation abnormality were independent prognostic factors for survival. Responses during initial treatments were also significant indicators of outcome.

Conclusion

Our study showed the unique predominance of a UNC13D mutation and vulnerability to Epstein–Barr virus infection in Korean children with HLH and emphasizes the prognostic significance of age, liver dysfunction, and treatment responses in this disease. A multicenter prospective trial that builds on the present results is warranted to identify subgroups of patients with a poor prognosis and identify optimal treatments.

A web-based delphi study for eliciting helpful criteria in the positive diagnosis of hemophagocytic syndrome in adult patients

The diagnosis of the reactive form of hemophagocytic syndrome in adults remains particularly difficult since none of the clinical or laboratory manifestations are specific. We undertook a study in order to elicit which features constitute helpful criteria for a positive diagnosis. In this Delphi study, the features investigated in the questionnaire and the experts invited to participate in the survey were issued from a bibliographic search. The questionnaire was iteratively proposed to experts via a web-based application with a feedback of the results observed at the preceding Delphi round. Experts were asked to label each investigated criterion in one of the following categories: absolutely required, important, of minor interest, or not assessable in the routine practice environment. A positive consensus was a priori defined as at least 75% answers observed in the categories absolutely required and important. The questionnaire investigated 26 criteria and 24 experts originating from 13 countries participated in the second and final Delphi round. A positive consensus was reached for the nine following criteria: unilineage cytopenia, bicytopenia, pancytopenia, presence of hemophagocytosis pictures on a bone marrow aspirate or on a tissue biopsy, high ferritin level, fever, organomegaly, presence of a predisposing underlying disease, and high level of lactate dehydrogenase. A negative consensus was reached for 13 criteria, and an absence of consensus was observed for 4 criteria. The study constitutes the first initiative to date for defining international guidelines devoted to the positive diagnosis of the reactive form of hemophagocytic syndrome.

HHV-8-negative, idiopathic multicentric Castleman disease: novel insights into biology, pathogenesis, and therapy

Multicentric Castleman's disease (MCD) describes a heterogeneous group of disorders involving proliferation of morphologically benign lymphocytes due to excessive proinflammatory hypercytokinemia, most notably of interleukin-6. Patients demonstrate intense episodes of systemic inflammatory symptoms, polyclonal lymphocyte and plasma cell proliferation, autoimmune manifestations, and organ system impairment. Human herpes virus-8 (HHV-8) drives the hypercytokinemia in all HIV-positive patients and some HIV-negative patients. There is also a group of HIV-negative and HHV-8-negative patients with unknown etiology and pathophysiology, which we propose referring to as idiopathic MCD (iMCD). Here, we synthesize what is known about iMCD pathogenesis, present a new subclassification system, and propose a model of iMCD pathogenesis. MCD should be subdivided into HHV-8-associated MCD and HHV-8-negative MCD or iMCD. The lymphocyte proliferation, histopathology, and systemic features in iMCD are secondary to hypercytokinemia, which can occur with several other diseases. We propose that 1 or more of the following 3 candidate processes may drive iMCD hypercytokinemia: systemic inflammatory disease mechanisms via autoantibodies or inflammatory gene mutations, paraneoplastic syndrome mechanisms via ectopic cytokine secretion, and/or a non-HHV-8 virus. Urgent priorities include elucidating the process driving iMCD hypercytokinemia, identifying the hypercytokine-secreting cell, developing consensus criteria for diagnosis, and building a patient registry to track cases.

Hemophagocytic Syndrome and Critical Illness: New Insights into Diagnosis and Management

Hemophagocytic lymphohistiocytosis (HLH) comprises a heterogeneous group of diseases that are characterized by a hyperinflammatory state due to uncontrolled T cell, macrophage, and histiocyte activation, accompanied by excessive cytokine production. This rare condition is almost uniformly fatal unless promptly recognized and treated. Much progress has been made in the last two decades in our understanding of the mechanisms underlying familial, and to a lesser extent, acquired cases of HLH. Recurrent mutations in more than 10 different genes have now been identified, involving biological pathways converging on intracellular vesicle trafficking and cytolytic granule exocytosis. Mechanisms underlying the majority of patients with acquired HLH, however, remain elusive, hampering both diagnostic evaluation and therapeutic management of these patients. Given that the majority of intensive care unit (ICU) patients with sepsis or multiorgan failure share many features of HLH, it is especially critical for pediatric and adult intensivists to be able to recognize patients with bona fide HLH and initiate treatment without delay. In this article, we review our current understanding of the pathophysiology, clinical testing, diagnosis, and treatment of patients with HLH, especially as it pertains to the care of critically ill patients in pediatric and medical ICUs.

Sphingosine-1 phosphate and central nervous system

The development of fingolimod, an unselective functional antagonist of the interactions between sphingosine 1 phosphate (S1P) and sphingosine 1 phosphate receptors (S1PRs), as the first oral therapy for multiple sclerosis (MS) has been a milestone. The parallel intensive research on the role of S1P, sphingosine kinases, and the five known S1PRs, their tissue distribution and expression in physiological and pathological conditions have led to a wide range of interesting findings. The initial focus of this research in the context of developing fingolimod as a treatment of MS has been on its immunological effects. The wide distribution and important roles of sphingosine, its metabolites, and their receptors in the central nervous system (CNS) in general, in myelin, and in all cell types of this organ have spurred interest to examine S1P and its five receptors in the brain as well. The present review will concentrate on the latter area and give a brief overview of what is known about S1P/S1PR interactions in the CNS in physiological and pathological conditions.

Lipopolysaccharide-induced multinuclear cells: increased internalization of polystyrene beads and possible signals for cell fusion

A murine macrophage-derived line, RAW264.7, becomes multinuclear on stimulation with lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria. These multinuclear cells internalized more polystyrene beads than mononuclear cells or osteoclasts (Nakanishi-Matsui, M., Yano, S., Matsumoto, N., and Futai, M., 2012). In this study, we analyzed the time courses of cell fusion in the presence of large beads. They were internalized into cells actively fusing to become multinuclear. However, the multinuclear cells once formed showed only low phagocytosis activity. These results suggest that formation of the multinuclear cells and bead internalization took place simultaneously. The formation of multinuclear cells was blocked by inhibitors for phosphoinositide 3-kinase, phospholipase C, calcineurin, and c-Jun N-terminal kinase. In addition, interleukin 6 and 10 also exhibited inhibitory effects. These signaling molecules and cytokines may play a crucial role in the LPS-induced multinuclear cell formation.

Mechanisms of liver involvement in systemic disease

The liver may be injured during the course of many systemic diseases. The mechanisms of injury can be broadly divided into four pathways: vascular, toxic, immune, and hormonal. Vascular obstruction may be an early event but is also the late common pathway from all mechanisms. Despite the large number of possible initiating factors, the end results are few, including death of hepatocytes or cholangiocytes, leading to the stereotyped syndromes of acute liver failure, non-cirrhotic portal hypertension, or cirrhosis. This small number of outcomes is a reflection of the few anatomic patterns that can be generated by microvascular obstruction. Vascular obstruction may occur by thrombosis, inflammation, or congestive injury. The innate immunity pathway is activated by endotoxin and other agents, leading to inflammatory infiltration, release of cytokines and reactive oxygen species, and necrosis. The adaptive immune pathway involves the generation of antibodies and antigen-specific cell-mediated attack on hepatic cells. Hormonal effects are principally involved when overnutrition leads to hyperinsulinemia followed by hepatocellular necrosis.