Familial hemophagocytic lymphohistiocytosis: improved neurodevelopmental outcome after bone marrow transplantation

Hematopoietic cell transplantation for hemophagocytic lymphohistiocytosis: recent advances and controversies

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory clinical syndrome of uncontrolled immune response which results in hypercytokinemia due to underlying primary or secondary immune defect. A number of genetic defects in transport, processing and function of cytotoxic granules which result in defective granule exocytosis and cytotoxicity of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells have been well identified at the cellular and molecular level. Important advances have been made during the last 20 years in the diagnosis and treatment of HLH. The Histiocyte Society has proposed diagnostic guideline using both clinical and laboratory findings in HLH-2004 protocol, and this has been modified partly in 2009. HLH used to be a fatal disease, but the survival of HLH patients has improved to more than 60% with the use of chemoimmunotherapy combined with hematopoietic cell transplantation (HCT) over the past 2 decades. However, HCT is still the only curative option of treatment for primary HLH and refractory/relapsed HLH after proper chemoimmunotherapy. The outcome of HCT for HLH patients was also improved steadily during last decades, but HCT for HLH still carries significant mortality and morbidity. Moreover, there remain ongoing controversies in various aspects of HCT including indication of HCT, donor selection, timing of HCT, conditioning regimen, and mixed chimerism after HCT. This review summarized the important practical issues which were proven by previous studies on HCT for HLH, and tried to delineate the controversies among them.

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.

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 mimicking surgical symptoms and complications: lessons learned from four cases

OBJECTIVE

Hemophagocytic lymphohistiocytosis (HLH) is a severe immunological disorder that leads to a massive inflammatory reaction that may prove rapidly fatal. We show that HLH may present by masquerading as surgical disease or as a postoperative complication leading to delays in diagnosis and treatment.

STUDY DESIGN

A case series of four children with acute surgical presentation and prolonged unexplained postoperative sepsis, who were diagnosed with HLH.

RESULTS

Four children with different clinical presentations (1. neonatal abdominal distension, 2. ileostomy closure and Hirschsprung's disease, 3. iatrogenic sigmoid perforation and Crohn's disease, and 4. streptococcal toxic shock syndrome with primary peritonitis) were diagnosed with HLH at our regional pediatric surgical centre in the last two years. All developed signs of prolonged postoperative sepsis with hepatosplenomegaly and pancytopenia, requiring intensive care support. In the absence of explanation for their symptoms and deteriorating clinical condition, a total of six 'negative' exploratory laparotomies were performed. Eventually, HLH was diagnosed with bone marrow aspiration after an average of 23 days (range 17-40), following the finding of significantly elevated ferritin (up to 293150 ng/ml) and triglyceride levels. All children improved with initiation of high-dose steroid treatment followed by etoposide and cyclosporin.

CONCLUSION

HLH may rarely present with symptoms and signs of surgical disease or complicate post-operative recovery. This diagnosis should be considered in children with unexplained prolonged fever, hepatosplenomegaly and pancytopenia, especially if associated with high ferritin levels. HLH can prove rapidly fatal without appropriate treatment.

Treatment of recurrent CNS disease post-bone marrow transplant in familial HLH

CNS involvement in Hemophagocytic Lymphohistiocytosis (HLH) has been reported in 63-73% of children at diagnosis [Haddad et al. (1997); Blood 89: 794-800; Horne et al. (2008); Br J Haematol 140: 327-335]. Patients can present with neurologic symptoms, abnormal CSF cytology, abnormal neuro-imaging, or a combination of these findings. CNS involvement is usually associated with a poor prognosis and increased mortality. The 3 year overall survival is 44% in patients with CNS involvement compared to 67% in patients without CNS involvement at diagnosis [Horne et al. (2008); Br J Haematol 140: 327-335]. We describe a treatment strategy employing systemic dexamethasone to control CNS disease in a patient with familial HLH and persistent CNS disease post Bone Marrow Transplant.

Recent advances in the diagnosis and treatment of hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disease of severe hyperinflammation caused by uncontrolled proliferation of activated lymphocytes and macrophages secreting high amounts of inflammatory cytokines. It is a frequent manifestation in patients with predisposing genetic defects, but can occur secondary to various infectious, malignant, and autoimmune triggers in patients without a known genetic predisposition. Clinical hallmarks are prolonged fever, cytopenias, hepatosplenomegaly, and neurological symptoms, but atypical variants presenting with signs of chronic immunodeficiency are increasingly recognized. Impaired secretion of perforin is a key feature in several genetic forms of the disease, but not required for disease pathogenesis. Despite progress in diagnostics and therapy, mortality of patients with severe HLH is still above 40%. Reference treatment is an etoposide-based protocol, but new approaches are currently explored. Key for a favorable prognosis is the rapid identification of an underlying genetic cause, which has been facilitated by recent immunological and genetic advances. In patients with predisposing genetic disease, hematopoietic stem cell transplantation is performed increasingly with reduced intensity conditioning regimes. Current research aims at a better understanding of disease pathogenesis and evaluation of more targeted approaches to therapy, including anti-cytokine antibodies and gene therapy.

Hemophagocytic lymphohistiocytosis (HLH) and related disorders

Hemophagocytic lymphohistiocytosis (HLH), which has many genetic causes, is characterized by multi-system inflammation. HLH is a reactive process resulting from prolonged and excessive activation of antigen presenting cells (macrophages, histiocytes) and CD8(+) T cells. Hemophagocytosis, which is mediated through the CD163 heme-scavenging receptor, is a hallmark of activated macrophages/histiocytes and is the characteristic finding for which the disorder was named. The majority of genetic causes identified to date affect the cytotoxic function of NK and T cells, crippling immunologic mechanisms that mediate natural immune contraction. The predominant clinical findings of HLH are fevers (often hectic and persistent), cytopenias, hepatitis and splenomegaly. Due to the life-threatening implications of the diagnosis of genetically determined HLH, antiinflammatory therapy, often consisting of steroids, etoposide or antithymocyte globulin (ATG), should be instituted promptly, followed by curative hematopoietic cell transplantation. Secondary HLH, associated with autoimmune disorders or viral infections in teens and adults, also carries a significant mortality rate and should be managed in consultation with specialists familiar with the diagnosis and treatment of such disorders.

Hemophagocytic lymphohistiocytosis and other hemophagocytic disorders

Hemophagocytic disorders result when critical regulatory pathways responsible for the natural termination of immune/inflammatory responses are disrupted or overwhelmed. Hemophagocytic disorders reflect pathologic defects that alter the normal crosstalk between innate and adaptive immune responses, and compromise homeostatic removal of cells that are superfluous or dangerous to the organism. Although hemophagocytic disorders are considered rare, increased awareness of these conditions has led to more frequent diagnoses, more rapid initiation of life-saving treatments, and new insights into the molecules and pathways involved in natural immune down-regulation. Furthermore, improved understanding of the immunologic abnormalities revealed by hemophagocytic disorders informs potential new treatments for life-threatening multisystem organ dysfunction related to sepsis in the intensive care unit setting and severe cases.

Fatal sibling cases of familial hemophagocytic lymphohistiocytosis (FHL) with MUNC13-4 mutations: case reports

The authors report here sibling cases of familial hemophagocytic lymphohistiocytosis (FHL) type 3 that took fatal courses despite intensive treatment. The older brother achieved remission by immunochemotherapy, but a central nervous system lesion occurred before the introduction of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The patient died on day +1 of allo-HSCT due to progression of the disease. The younger brother developed symptoms of hemophagocytic lymphohistiocytosis mimicking neonatal hemochromatosis at birth. He died without a chance to receive allo-HSCT. Both siblings showed low natural killer cell (NK) activity and the compound heterozygous Munc13-4 gene mutations 1596+1 and 1723insA were identified postmortem in the younger brother. With recent progress in the molecular diagnosis of FHL, prompt and most appropriate therapeutic measures should be introduced to improve the prognosis of FHL patients.

Sensorineural hearing loss in a case of familial hemophagocytic lymphohistiocytosis

Severe sensorineural hearing loss (bilateral >80 dB) was diagnosed in a case of familial hemophagocytic lymphohistiocytosis (FHL). The female patient developed HLH at 3 months of age and underwent allogeneic cord blood transplantation at 11 months of age following 7 months of immuno-chemotherapy. The type 2 FHL patient had a homozygous perforin gene mutation of 1090-1091delCT, and was noted to have hearing loss at 3.5 years of age. Retrospective evaluation did not clarify the exact causes of hearing loss. Reports on Kawasaki disease, suggesting a correlation between severe inflammatory status in infancy and the development of sensorineural hearing loss, may shed some light on this rare complication in this case of FHL. Considering the markedly improved prognosis of FHL due to recent advances made in the molecular diagnosis and in the management including allogeneic hematopoietic stem cell transplantation, auditor by screening might be warranted for surviving FHL patients.

Fetal and neonatal histiocytoses

PURPOSE

The histiocytoses are a group of disorders of the monophagocytic system having a variety of clinical and pathological findings. They occur less often during the perinatal period than later in life. Their biologic behavior, response to therapy, and histologic types are not the same.

METHODS

The study consisted of 221 fetuses and neonates collected from the literature and from personal files.

RESULTS

Langerhans' cell histiocytosis (LCH), the hemophagocytic lymphohistiocytoses (HLH), and juvenile xanthogranuloma (JXG), in order of rank, were the main histiocytoses occurring in the perinatal period. HLH accounted for the highest mortality (74%) followed by disseminated LCH (52%) and JXG (11%). All neonates with LCH and JXG limited to the skin and/or subcutaneous tissue survived with or without treatment.

CONCLUSIONS

This study suggests that there is an increased incidence of spontaneous regression of certain histiocytic lesions in neonates as compared to older individuals. Cutaneous forms JXG and LCH had the highest incidence of regression followed by infection associated HLH.

A rare syndrome in the differential diagnosis of hepatosplenomegaly and pancytopenia: report of identical twins with Griscelli disease

White, identical twin boys aged 3 months were referred to our centre with persisting fever, mouth ulcers, hepatosplenomegaly, pancytopenia and failure to thrive. The parents were first cousins and there was a history of a sibling with similar manifestations who had died. The infants had silvery-grey hair and pigment clumps on the hair shafts, and skin biopsy showed accumulation of melanocytes on melanosomes. Bone marrow revealed hypercellularity and haemophagocytosis. HLH-94 chemotherapy (initial therapy with daily dexamethasone and etoposide, maintenance with dexamethasone pulses, etoposide and cyclosporin A) was started. Though partial haematological remission was achieved, one of the boys died on the 34th day following aspiration pneumonia. No pathogen could be identified. The second boy responded to therapy but had a haematological relapse and died 68 days after first being admitted. Genetic study revealed a 5 bp deletion in the RAB27A gene (510 del AAGCC in exon 5). Transient haematological remission can be achieved with chemotherapy but allogeneic bone marrow transplantation is the only curative therapy in Griscelli disease, as in other familial haemophagocytic syndromes. Identification of the mutation also provides an opportunity for prenatal diagnosis.

Low natural killer activity and central nervous system disease as a high-risk prognostic indicator in young patients with hemophagocytic lymphohistiocytosis

BACKGROUND

Familial hemophagocytic lymphohistiocytosis HLH (FHL) is fatal, unless patients are rescued with hematopoietic stem cell transplantation (SCT). Although the molecular identification of FHL now is possible at least in part from perforin gene study, many cases escape detection or never are tested due to the lack of specific hallmarks, making diagnosis difficult. To the authors' knowledge, it remains to be determined whether persistently low natural killer cell (NK) activity and a high incidence of central nervous system (CNS) disease increase the probability of FHL.

METHODS

The authors analyzed 42 HLH patients age < 2 years, 13 of whom developed overt CNS disease and 5 of whom demonstrated persistently deficient NK activity (Group 1). The remaining 24 patients had no CNS disease and had NK activity of moderate decrease to within the normal range (Group 2).

RESULTS

In Group 1, CNS symptoms were detected in 6 cases within 1 month and between 4.5-9 months in 6 other patients. In these cases, spotty lesions demonstrating a high T2 signal in the white matter were noted on brain magnetic resonance imaging. The survival was significantly poor for patients in Group 1 unless they were rescued with SCT, which was performed in 5 of the 13 patients with CNS disease and in all 5 patients with persistent NK activity deficiency. SCT was successful in 9 patients, with no CNS sequelae reported after the transplantation. Conversely, the prognosis of the 24 patients in Group 2 was better and only 1 patient required SCT.

CONCLUSIONS

Very young HLH patients (age < 2 years) who are at high risk of fatal FHL with persistently deficient NK activity and/or overt CNS disease require appropriate SCT to reverse CNS disease and achieve a complete cure.

Hemophagocytic lymphohistiocytosis presenting with thrombocytopenia in the newborn

Hemophagocytic lymphohistiocytosis (HLH) may present with thrombocytopenia during the newborn period. Three neonates (one term and two preterm) presented during the newborn period with thrombocytopenia. Transient recovery occurred in two newborns. The diagnosis of HLH was made after the recurrence of thrombocytopenia and the clinical symptoms at 5 and 7 weeks. The third infant was a premature baby diagnosed at 8 days of age after manifesting the clinical and laboratory features of HLH. All three neonates were treated with chemotherapy and responded well. After hematologic and clinical remission was achieved, the two newborns received hematopoietic stem cell transplantation from allogeneic donors. The third neonate is currently receiving chemotherapy. Persistent or recurrent thrombocytopenia of undetermined cause during the neonatal period should raise the suspicion of HLH, even though other symptoms or signs are not yet evident.

Recent developments in the management of haemophagocytic lymphohistiocytosis

Over the past two decades, the underlying pathophysiology of haemophagocytic lymphohistiocytosis (HLH) (synonyms: haemophagocytic syndrome, macrophage activation syndrome) has been well recognised. Cytokine storm plays a major role, which derives from an inappropriate immune reaction caused by proliferating and activated T-cell or natural killer (NK) cells associated with macrophage activation and inadequate apoptosis of immunogenic cells. Many biological parameters reflecting activity of disease or response to treatment have been identified, in particular, serum ferritin has been confirmed to be one of the markers for HLH. The common types of HLH consist of non-hereditary (acquired) infection-associated disease such as Epstein-Barr virus (EBV)-haemophagocytic lymphohistiocytosis (HLH) and hereditary (familial) disease such as FHL, in which, at the molecular level, dysfunctional perforin was clarified. Regarding the therapeutic strategies, prompt differential diagnosis of underlying disease is essential and choice of treatment should be based on the risk (low or high) of prognosis, where either cyclosporin A, steroids or iv. immunoglobulin (IVIG) may be indicated as initial treatment for low-risk patients, with etoposide-containing regimens for high-risk patients. Significant improvement of prognosis has been obtained by incorporating intensive supportive care at the disease onset and prompt introduction of immunosuppressants to control cytokine storm. Subsequent immunochemotherapy and haemopoietic stem cell transplantation have contributed significantly to further improve survival of hereditary and refractory HLH patients.