Hemophagocytic lymphohistiocytosis and related disorders

PURPOSE OF REVIEW: The rate of diagnosis of hemophagocytic lymphohistiocytosis, a genetically heterogeneous and, frequently, rapidly fatal autosomal recessive disorder of immune regulation, is increasing worldwide. Awareness has grown through the Histiocyte Society and the publication of newly-recognized genetic causes. I summarize current knowledge regarding the pathophysiology, diagnosis and treatment of hemophagocytic lymphohistiocytosis. RECENT FINDINGS: Genetic defects leading to life-threatening hemophagocytic syndromes have recently been described. Two autosomal recessive gene defects underlie 40-50% of primary (familial) cases worldwide: perforin, the major immune cytotoxic protein, and MUNC 13-4, a protein involved in exocytosis of perforin-bearing cytotoxic granules during apoptosis. Related autosomal recessive defects of secretory cytotoxic lysosomes - LYST 1 (Chediak-Higashi syndrome), Rab27A (Griscelli syndrome), and X-linked lymphoproliferative disorder - also carry a very high risk of fatal hemophagocytic lymphohistiocytosis. Concurrently, treatment protocols involving multiagent immunomodulatory therapy followed by allogeneic hematopoeitic cell transplantation have been tested. With immunomodulatory treatment, 75% of children with hemophagocytic lymphohistiocytosis are symptomatically improved after 2 months of therapy. Disease-free survival after allogeneic hematopoeitic cell transplantation currently ranges from 50 to 70%. SUMMARY: Bench and clinical research have advanced understanding of the pathophysiology of hemophagocytic lymphohistiocytosis and related disorders, and significantly improved clinical outcomes during the past decade.     

Sequential respiratory syncytial virus cytomegalovirus pneumonia following bone marrow transplantation

A 6-month-old child with familial hemophagocytic lymphohistiocytosis (FHL) experienced early sequential pneumonia due to respiratory syncytial virus (RSV) and cytomegalovirus (CMV) following bone marrow transplantation (BMT). The patient was deficient in natural killer (NK) cell activity (as found frequently in patients with FHL), and this risk factor may have played a major role in the concomitant infection by the two viral pathogens. Rapid diagnostic methods for both viruses are essential and early specific treatment may serve to ameliorate RSV- and CMV-induced lung injury in these life-threatening infections. © 1995 Wiley-Liss, Inc.     

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 or sufficient for the diagnosis of HLH, as it may be seen in a variety of reactive conditions, or may be absent in true HLH. Nevertheless, the finding of hemophagocytosis in specific clinical situations should prompt the 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, morphologic aspects hemophagocytosis and its associated histologic findings in different tissues and give a brief overview of diagnostic criteria and clinical evaluation.     

Familial hemophagocytic lymphohistiocytosis

The cytologic features of familial hemophagocytic lymphohistiocytosis in two infant siblings were reviewed and compared to the histopathologic features in the same cases. The cytologic features of familial hemophagocytic lymphohistiocytosis in imprint smears from the spleen, lymph nodes, and liver were distinct, with proliferation of benign histiocytes engulfing erythrocytes and platelets. Hemophagocytic activity was more readily identifiable in imprint smears than in paraffin-embedded histologic sections. The differential diagnosis of histiocytic proliferative syndromes is also discussed.     

Evaluation of lymphocyte function by IFN-γ secretion capability assay in the diagnosis of lymphoma-associated hemophagocytic syndrome

Lymphoma-associated hemophagocytic syndrome (LAHS) is a highly life-threatening disease characterized by an uncontrolled immune disorder. Both under-recognition and delayed diagnosis may contribute to aggressive diseases, and a poorer prognosis. Identification of laboratory features specific for LAHS patients may allow for early detection and intervention with improved outcomes. In the present study, 120 lymphoma patients at first diagnosis were recruited and the function of lymphocytes was evaluated by IFN-γ secretion assay at first diagnosis and follow up. During the surveillance period, 20 patients who complicated with hemophagocytic lymphohistiocytosis (HLH) were classified as LAHS group, and 30 patients without infectious diseases during the course of treatment were classified as lymphoma control group. In addition, 20 non-malignant associated HLH patients recruited as HLH control group and 50 healthy control (HC) subjects were also included. The IFN-γ secretion capability of lymphocytes was compared between first diagnosis of lymphoma patients who was complicate with HLH or not in the disease progression. Our results showed that only NK cell activity was decreased in lymphoma control group, but the activities of NK, CD4+ and CD8+ T cells were all significantly decreased at the time of lymphoma diagnosis in those who would progress with HLH. During the course of treatment, lymphocyte function was relatively stable in lymphoma patients but became further decreased when suffering from complication of LAHS. The IFN-γ secretion capability of lymphocytes in LAHS and non-malignant associated HLH patients were all significantly decreased compared with HCs. So the occurrence of HLH was the key factor leading to the impaired activity of lymphocytes. These data suggest that decreased lymphocyte function might be used as a predictor of LAHS, which has critical clinical significance in diagnosis and further understanding the pathogenesis of the disease.     

Contemporary diagnostic methods for hemophagocytic lymphohistiocytic disorders

Hemophagocytic lymphohistiocytosis is a life-threatening multi-system hyperinflammatory disorder characterized by dysfunctional cytolytic lymphocyte responses, hypercytokinemia, and widespread lymphohistiocytic tissue infiltration and destruction. Diagnosis and definitive therapy are often delayed as clinical efforts are directed toward treatment of presumed overwhelming infection. Sporadic cases occur in association with underlying immune dysfunction related to autoimmune disease, malignancy, or severe infection. However, familial cases predominate with remarkable associations between underlying genetic defects and dysregulation of immune responses. Here, we review the genetic and immunologic basis of contemporary diagnostic methods for hemophagocytic lymphohistiocytosis.     

Clinical features and correct diagnosis of macrophage activation syndrome

Macrophage activation syndrome (MAS) is increasingly recognized among febrile hospitalized patients. Clinically, MAS resembles multiorgan dysfunction and shock. Laboratory features include hepatobiliary dysfunction, coagulopathy, pancytopenia, hyperferritinemia and markers of immune activation. Pathologically, hemophagocytosis is commonly seen but is only present in 60% of MAS patients. MAS, or secondary hemophagocytic lymphohistiocytosis (HLH), is triggered by infectious (e.g., herpes family viruses), rheumatologic (e.g., systemic lupus erythematosus [SLE]) and oncologic (e.g., T-cell leukemia) conditions. Formal HLH criteria, while specific, are frequently insensitive for MAS diagnosis. Thus, disease-specific (e.g., SLE) and generic MAS criteria have been published. Recently, novel criteria for MAS in children with systemic juvenile idiopathic arthritis (sJIA) were developed and are a key focus of this review.     

No mutations of SAP/SH2D1A/DSHP and perforin genes in patients with Epstein-Barr virus-associated hemophagocytic syndrome in Japan

Recently, mutations of two genes, SAP/SH2D1A/DSHP and perforin genes, have been identified in two fatal inherited lymphoproliferative diseases, X-linked lymphoproliferative disease and familial hemophagocytic lymphohistiocytosis, respectively. Epstein-Barr virus (EBV)-associated hemophagocytic syndrome, a fulminant non-inherited T-cell lymphoproliferative disease, is relatively common in Japan and is extremely difficult to distinguish from X-linked lymphoproliferative disease and familial hemophagocytic lymphohistiocytosis, especially in sporadic cases, because of similarities in clinical and laboratory features. Mutation analysis was carried out of samples obtained from 14 patients with EBV-associated hemophagocytic syndrome by sequencing the genomic SAP/SH2D1A/DSHP and perforin genes. However, a specific mutation was not identified in either of the genes, suggesting that mutations of the SAP/SH2D1A/DSHP and perforin genes are not responsible for the pathogenesis of EBV-associated hemophagocytic syndrome in Japan.     

Fever of unknown origin in a patient of systemic onset juvenile idiopathic arthritis

Hemophagocytic lymphohistiocytosis is a potentially fatal condition characterized by pathologic immune activation, which can complicate infections, childhood systemic rheumatologic diseases and malignancies. Here we report a case of reactive hemophagocytic lymphohistiocytosis [macrophage activation syndrome] complicating systemic onset juvenile idiopathic arthritis, which was treated successfully with dexamethasone and cyclosporine. Reactive hemophagocytic lymphohistiocytosis or macrophage activation syndrome should be considered in patients of juvenile idiopathic arthritis with prolonged fever of unknown origin and cytopenias. Early diagnosis with high index of suspicion and prompt, aggressive treatment are needed for successful outcomes.     

Trigger-dependent differences determine therapeutic outcome in murine primary hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is a hyperinflammatory syndrome affecting patients with genetic cytotoxicity defects. Perforin-deficient (PKO) mice recapitulate the full clinical picture of FHL after infection with lymphocytic choriomeningitis virus (LCMV). Hyperactivated CD8⁺ T cells and IFN-γ have been identified as the key drivers of FHL and represent targets for therapeutic interventions. However, the response of patients is variable. This could be due to trigger-dependent differences in pathogenesis, which is difficult to address in FHL patients, since the trigger frequently escapes detection. We established an alternative FHL model using intravenous infection of PKO mice with murine CMV (MCMV)_Smith. PKO mice developed acute FHL after both infections and fulfilled HLH diagnostic criteria accompanied by excessive IFN-γ production by disease-inducing T cells, that enrich in the BM. However, direct comparison of the two infection models disclosed trigger-dependence of FHL progression and revealed a higher contribution of CD4 T cells and NK cells to IFN-γ production after MCMV infection. Importantly, therapeutic intervention by IFN-γ neutralization or CD8⁺ T-cell depletion had less benefit in MCMV-triggered FHL compared to LCMV-triggered FHL, likely due to MCMV-induced cytopathology. Thus, the context of the specific triggering viral infection can impact the success of targeted immunotherapeutic HLH control.     

Genetic basis of hemophagocytic lymphohistiocytosis syndrome (Review).

The group of immune disorders which leads to the occurrence of hemophagocytic lymphohistiocytosis (HLH) syndrome presents a strange paradox in that patients with these conditions associate a dramatic immune response to infection with the failure to establish an effective immune response. During the last few years, significant progress was made in the characterization and the understanding of the molecular basis involved in these inherited immune disorders. The hemophagocytic lymphohistiocytosis syndrome which characterized the evolution of the Chediak-Higashi syndrome and the Griscelli disease results from defects affecting intracellular trafficking. A defective SH2 protein interacting with T lymphocyte intracellular signaling pathways is the cause of the X-linked lymphoproliferative disease, whereas at least three distinct genetic defects can lead to the familial hemophagocytic lymphohistiocytosis. The molecular characterization of these latter defects is in progress. This review summarizes the recent advances as well as their implications in the diagnosis and the understanding of the physiopathology of these disorders.     

Hemophagocytic Syndrome in Children and Adults

Hemophagocytic syndrome, also known as hemophagocytic lymphohistiocytosis (HLH), is a heterogenic syndrome, which leads to an acute, life-threatening inflammatory reaction. HLH occurs both in children and adults, and can be triggered by various inherited as well as acquired factors. Depending on the etiology, HLH can be divided into genetic (i.e., primary) and acquired (i.e., secondary) forms. Among genetic HLH forms, one can distinguish between familial HLH and other genetically conditioned forms of HLH. Acquired HLH can be typically triggered by infections, autoimmune diseases, and malignancies. The most common symptoms of HLH are unremitting fever, splenomegaly, and peripheral blood cytopenia. Some severely ill patients present with central nervous system involvement. Laboratory tests reveal hyperferritinemia (often >10,000 μg/L), increased serum concentration of soluble receptor α for interleukin-2 (>2,400 U/L), hypertriglyceridemia, hypofibrinogenemia, coagulopathy, hyponatremia, hypoproteinemia, and elevated liver transaminases and bilirubin. Prognosis in HLH is very serious. Genetic HLH is always lethal if adequate therapy is not administered. Similarly, severe acquired cases often lead to death without appropriate treatment. Since HLH can be encountered by various specialists in the medical field, basic knowledge of this entity such as diagnostic criteria and treatment should be familiar to all physicians.     

Clinical presentation of hemophagocytic lymphohistiocytosis in adults is less typical than in children

OBJECTIVE:

Hemophagocytic lymphohistiocytosis in adults is largely underdiagnosed. To improve the rate and accuracy of diagnosis in adults, the clinical and laboratory characteristics of hemophagocytic lymphohistiocytosis were analyzed in and compared between adults and children in a Chinese cohort.

METHOD:

Data from 50 hemophagocytic lymphohistiocytosis patients, including 34 adults and 16 children who fulfilled the 2004 hemophagocytic lymphohistiocytosis diagnostic criteria, were collected and analyzed.

RESULTS:

1. Etiological factors: The proportion of Epstein-Barr virus infection was lower in adults compared with children, whereas fungal infection and natural killer/T cell lymphoma were more frequent in adults (P<0.05). 2. Clinical manifestations and laboratory findings: Over 90% of adults and pediatric patients presented with fever, thrombocytopenia and high serum ferritin levels. However, in adults, the proportions of hepatomegaly, splenomegaly and jaundice were much lower (P<0.01) than in children, and serous cavity effusion was more frequent in adult patients (P<0.05). More children had hemoglobin <90 g/L, total bilirubin >19 mmol/L and lactate dehydrogenase >500 U/L compared with adults (P<0.05). 3. The time interval from the onset of symptoms to clinical diagnosis was significantly shorter in pediatric patients than in adults (P<0.05).

CONCLUSIONS:

Certain clinical features were different between the two groups. The less characteristic clinical presentation of hemophagocytic lymphohistiocytosis in adults may make the disease more difficult to diagnose. Our findings suggest that hemophagocytic lymphohistiocytosis should be considered when an adult patient presents with the above-mentioned symptoms.     

Acute human immunodeficiency virus syndrome presenting with hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) has been described in patients with advanced stages of human immunodeficiency virus (HIV) infection, but rarely occurs during the seroconversion stage of acute HIV infection. We report a case of acute HIV syndrome that presented with virus-associated HLH. The patient recovered spontaneously without any immunomodulating therapy. This case suggests that acute HIV infection should be included in the differential diagnosis of HLH and indicates that HLH associated with acute HIV infection can have a favorable outcome.     

Epstein–Barr virus infection–Related hemophagocytic lymphohistiocytosis

We report a case of 27-year-old female diagnosed with hemophagocytic lymphohistiocytosis (HLH) following a recent Epstein–Barr virus (EBV) infection. A known case of relapsing remitting multiple sclerosis on corticosteroids for last 6 months presented to the critical care unit with fever, maculopapular rash and difficulty in breathing. A rapid and correct diagnosis with the precise treatment led to complete recovery of this patient. The HLH is a rare complication of primary EBV infection.     

Serum neopterin levels as a diagnostic marker of hemophagocytic lymphohistiocytosis syndrome

The objective of this study was to retrospectively evaluate the utility of serum neopterin as a diagnostic marker of hemophagocytic lymphohistiocytosis (HLH). The medical records of patients diagnosed with HLH (familial and secondary) between January 2000 and May 2009 were reviewed retrospectively, and clinical and laboratory information related to HLH criteria, in addition to neopterin levels, was recorded. A group of 50 patients with active juvenile dermatomyositis (JDM) (who routinely have neopterin levels assessed) served as controls for the assessment of the accuracy, sensitivity, and specificity of neopterin as a diagnostic test for HLH. The Pearson correlation was used to measure the association between serum neopterin levels and established HLH-related laboratory data. Serum neopterin levels were measured using a competitive enzyme immunoassay. During the time frame of the study, 3 patients with familial HLH and 18 patients with secondary HLH were identified as having had serum neopterin measured (all HLH patients were grouped together). The mean neopterin levels were 84.9 nmol/liter (standard deviation [SD], 83.4 nmol/liter) for patients with HLH and 21.5 nmol/liter (SD, 10.13 nmol/liter) for patients with JDM. A cutoff value of 38.9 nmol/liter was 70% sensitive and 95% specific for HLH. For HLH patients, neopterin levels correlated significantly with ferritin levels (r = 0.76, P = 0.0007). In comparison to the level in a control group of JDM patients, elevated serum neopterin was a sensitive and specific marker for HLH. Serum neopterin has value as a diagnostic marker of HLH, and prospective studies are under way to further evaluate its role as a marker for early diagnosis and management of patients.     

Hemophagocytic lymphohistiocytosis: a hemophagocytic syndrome.

Hemophagocytic lymphohistiocytosis, terminology that designates a syndrome that may be familial or sporadic, with or without an associated viral infection, is presented as the prototype of a hemophagocytic syndrome, a condition in which there is uncontrolled activation of the cellular immune system. Diagnostic criteria include idiopathic fever, splenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, and the presence of hemophagocytosis. The surgical and autopsy pathology features infiltrates composed of lymphocytes and ordinary, but activated, histiocytes and hemophagocytosis. The chronic hepatitis-like hepatic lesion is noted to be characteristic, if not unique, in this age group and setting. Current concepts of pathophysiology focus on the role of cytokines, particularly interleukin (IL)-1, IL-2, soluble IL-2 receptor, plasminogen activator, and prostaglandins. The clinicopathologic features of the syndrome can be accounted for by the uncontrolled and unopposed production and release of these mediators. Nosology places hemophagocytic lymphohistiocytosis in the position of the most important of the "benign" histiocytosis syndromes that involve ordinary histiocytes of the mononuclear phagocytic system in contrast to Langerhans cell histiocytosis (histiocytosis X) in which pathological dendritic histiocytes are operative. Features that distinguish hemophagocytic lymphohistiocytosis from other disorders, such as malignant histiocytosis, X-linked lymphoproliferative disorder, congenital immunodeficiency states, the accelerated phase of Chediak-Higashi syndrome, and cytophagic histiocytic panniculitis, which may be associated with a hemophagocytic syndrome, are presented.     

Intravascular large B-cell lymphoma with hemophagocytic syndrome (Asian variant) in a Caucasian patient

Intravascular lymphoma is an aggressive and extremely rare extranodal lymphoma with neoplastic lymphoid cells confined exclusively within intravascular spaces. The histopathologic findings are subtle due to the rarity of the neoplastic cells in blood vessels. Clinical presentations are non-specific and focal space-occupying lesions or lymphoadenopathy are always lacking. It is a diagnostic challenge. Secondary hemophagocytic syndrome is uncommon and is typically associated with infection, malignancy, and suppressed immune states. Intravascular lymphoma has a strong association with hemophagocytic syndrome in Asian patients, the so-called "Asian variant", but not in Western patients. We report a case of intravascular B-cell lymphoma in a Caucasian patient associated with secondary hemophagocytic syndrome. The patient was diagnosed by core liver biopsy and successfully treated. This case demonstrates the importance of high index of suspicion and astute histopathologic examination in recognition of this unusual clinical and pathologic combination.     

Non-familial hemophagocytic lymphohistiocytosis

A case of non-familial hemophagocytic lymphohistiocytosis (HLH) is described. The patient had a chronic course being alive and doing relatively well 3 years since onset. The specific pathological features of this disorder are discussed with emphasis on the fact that a remarkable loss of lymph node structure is sustained by a mature lymphohistiocytic infiltrate. Erythrophagocytosis is assessed as an important but not specific finding. Lymphocyte depletion is an important feature of the lesion. The presence of overlapping features in HLH, infection-associated hemophagocytic syndrome (IAHS) and X-linked recessive lymphoproliferative syndrome (XLS) is emphasized.     

Pulmonary lymphomatoid granulomatosis in Griscelli syndrome type 2

Griscelli syndrome type 2 (GS2) is a rare autosomal-recessive disorder associated with a RAB27A gene mutation, and clinically manifesting as hypopigmentation, disseminated chronic encephalitis, and severe immunological disorders characterized by an accelerated hematological phase, also referred to as hemophagocytic syndrome (HS), or hemophagocytic lymphohistiocytosis (HLH). The authors report the diagnosis of GS2 in an 11-year-old girl with hypopigmentation, immunodeficiency, hepatosplenomegaly, severe neurological impairments, and fatal multiorgan failure. In this patient a diagnosis of pulmonary lymphomatoid granulomatosis (LG), an Epstein-Barr virus (EBV)-related lymphoproliferative disorder, was established from radiological and histological findings. Although EBV-related malignancies are common in immunocompromised patients, this is the first report of a diagnosis of pulmonary LG in a patient with GS2.