Severe COVID-19-associated hyperinflammatory syndrome versus classic hemophagocytic lymphohistiocytosis: similarities, differences, and the way forward.

The hyperinflammatory immune response in severe COVID-19 infection shares features with secondary hemophagocytic lymphohistiocytosis (sHLH) in the form of fever, cytopenia, elevated inflammatory markers, and high mortality. There are contrasting opinions regarding utility of HLH 2004 or HScore in the diagnosis of severe COVID-19-related hyperinflammatory syndrome (COVID-HIS). This was a retrospective study of 47 patients of severe COVID-19 infection, suspected to have COVID-HIS and 22 patients of sHLH to other illnesses, to evaluate the diagnostic utility and limitations of HLH 2004 and/or HScore in context to COVID-HIS and to also evaluate the utility of Temple criteria for predicting severity and outcome in COVID-HIS. Clinical findings, hematological, and biochemical parameters along with the predictor of mortality were compared between two groups. Only 6.4% (3/47) of cases fulfilled ≥5/8 HLH 2004 criteria and only 40.52% (19/47) of patients showed HScore >169 in COVID-HIS group. 65.9% (31/47) satisfied the Temple criteria in COVID-HIS as compared with 40.9% (9/22) in the non-COVID group (p = 0.04). Serum ferritin (p = 0.02), lactate dehydrogenase (p = 0.02), direct bilirubin (p = 0.02), and C-reactive protein (p = 0.03) were associated with mortality in COVID-HIS. Both HScore and HLH-2004 criteria perform poorly for identifying COVID-HIS. Presence of bone marrow hemophagocytosis may help to identify about one-third of COVID-HIS missed by the Temple Criteria.

An Unusual Case of Hemophagocytic Lymphohistiocytosis Associated with Mycobacterium chimaera or Large-Cell Neuroendocrine Carcinoma.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and very dangerous condition characterized by abnormal activation of the immune system, causing hemophagocytosis, inflammation, and potentially widespread organ damage. The primary (genetic) form, caused by mutations affecting lymphocyte cytotoxicity, is most commonly seen in children. Secondary HLH is commonly associated with infections, malignancies, and rheumatologic disorders. Most current information on diagnosis and treatment is based on pediatric populations. HLH is a disease that should be diagnosed and treated promptly, otherwise it is fatal. Treatment is directed at treating the triggering disorder, along with symptomatic treatment with dexamethasone and etoposide. We present a 56-year-old patient who was admitted with worsening weakness, exertional dyspnea, dry and nonproductive cough, and a 5-pound weight loss associated with loss of appetite. This is among the rare disorders that are not commonly encountered in day-to-day practice. Our differential diagnoses were broad, including infection, such as visceral leishmaniasis, atypical/tuberculous mycobacteria, histoplasmosis, Ehrlichia, Bartonella, Brucella, Adenovirus, disseminated herpes simplex virus (HSV), hematological-like Langerhans cell histiocytosis, or multicentric Castleman disease; drug reaction, such as drug rash with eosinophilia and systemic symptoms (DRESS); and metabolic disorder, including Wolman's disease (infantile lysosomal acid lipase deficiency) or Gaucher's disease. Based on our investigations as described in our case report, it was narrowed down to hemophagocytic lymphohistiocytosis and COVID-19. Two COVID-19 tests were negative. His lab abnormalities and diagnostic testing revealed hemophagocytic lymphohistiocytosis. He was empirically started on antibiotics and dexamethasone, to be continued for 2 weeks then tapered if the patient showed continued improvement. Dexamethasone was tapered over 8 weeks. He improved on just one of the Food and Drug Administration (FDA)-approved medications, proving that treatment should be tailored to the patient. In addition, in this case study, we included the background, etiology, pathogenesis, diagnosis, management, and prognosis of HLH.

Haemophagocytic lymphocytic histiocytosis/macrophage activation syndrome with acute inflammatory gastroenteritis.

Haemophagocytic lymphocytic histiocytosis (HLH) is a rare, life-threatening condition caused by abnormal activation of cytotoxic T lymphocytes, natural killer cells and macrophages resulting in hypercytokinaemia and immune-mediated injury of multiple organ systems. Secondary HLH occurs in the setting of a malignant, infectious or autoimmune stimulus. Macrophage activation syndrome (MAS) is the term used to describe HLH that develops secondary to rheumatological diseases such as lupus and juvenile idiopathic arthritis, among others. Commonly observed and documented symptoms include fever, organomegaly and lymphadenopathy. Given the potential for multiorgan failure in HLH/MAS, early identification, diagnosis and initiation of treatment is essential. We present a case of secondary HLH/MAS with acute inflammatory gastroenteritis in a middle-aged woman with a history of systemic lupus erythematosus.

Hemophagocytic lymphohistiocytosis diagnosed by bone marrow trephine biopsy in living post-COVID-19 patients: case report and mini-review.

Hemophagocytic lymphohistiocytosis (HLH) constitutes a life-threatening inflammatory syndrome. Postmortem histological findings of bone marrow (BM) from COVID-19 patients showed histiocytosis and hemophagocytosis and supported the hypothesis that secondary HLH (sHLH) may be triggered by SARS-CoV-2 infection. However, there are a limited number of sHLH cases in which trephine has been performed in living post-COVID-19 patients. Here we present a recent case and a mini-review of sHLH diagnosed by trephine biopsy in living patients after COVID-19. An 81-year-old man with a past medical history of hypertension, diabetes, ischemic stroke, was referred to the hospital to evaluate leukocytosis, pyuria, and elevation of inflammatory markers four weeks after recovering from COVID-19. Computed tomography of the abdomen did not reveal focal signs of infection or hepatosplenomegaly. The patient received intravenous meropenem and two packed red blood cell units. Leukocytes and C-reactive protein were gradually decreased. A BM biopsy was performed and the patient was discharged on cefixime. BM smear revealed severe anemia, lymphopenia, and dysplastic morphologic findings of erythroblasts, neutrophils, and megakaryocytes. Trephine biopsy revealed hypercellular marrow dyserythropoiesis, plasmacytosis, lymphocytosis, histiocytosis, hemophagocytosis, and the absence of granulomas or carcinoma. Immunohistochemistry documented a mixed population of T lymphocytes (CD3+) and B lymphocytes (CD20+). Strong positivity for CD68 confirmed histiocytosis. CD138 κ, λ staining proved polyclonal plasmacytosis. Perl's staining showed excess hemosiderin deposits. Based on our findings, we document sHLH in trephine BM biopsy of a living post-COVID-19 patient and persistent leukocytosis, underscoring the diagnostic value of trephine biopsy in preventing life-threatening conditions such as COVID-19.

Severe Pediatric COVID-19 Pneumonia Treated With Adjuvant Anakinra.

BACKGROUND AND OBJECTIVES: To compare previous hemophagocytic lymphohistiocytosis criteria with adult coronavirus disease 2019 (COVID-19)-associated hyperinflammatory syndrome (cHIS) criteria for the diagnosis of hyperinflammation in pediatric patients with COVID-19. The secondary objective was to assess treatment response to intravenous (IV) anakinra in these patients. METHODS: This case series included children admitted to the PICU for COVID-19 pneumonia with hyperinflammation and treated with IV anakinra between July 2020 to April 2021. Hyperinflammatory criteria were determined for each patient. Clinical course, chest imaging, and inflammatory marker trends were assessed pre- and post-anakinra treatment. RESULTS: All patients had a cHIS criteria score of ≥5. Two patients met 2004-hemophagocytic lymphohistiocytosis criteria. Only the patient that required extracorporeal membrane oxygenation met the H-Score cut-off value. All but one patient had a decrease in their inflammatory markers and improvement in clinical status with early initiation of adjunctive IV anakinra. CONCLUSIONS: In this case series, adult cHIS criteria were successfully used to identify pediatric COVID-19 patients with hyperinflammation. Ferritin levels decreased after the early initiation of IV anakinra.

Severe COVID-19 Shares a Common Neutrophil Activation Signature with Other Acute Inflammatory States.

Severe COVID-19 patients present a clinical and laboratory overlap with other hyperinflammatory conditions such as hemophagocytic lymphohistiocytosis (HLH). However, the underlying mechanisms of these conditions remain to be explored. Here, we investigated the transcriptome of 1596 individuals, including patients with COVID-19 in comparison to healthy controls, other acute inflammatory states (HLH, multisystem inflammatory syndrome in children [MIS-C], Kawasaki disease [KD]), and different respiratory infections (seasonal coronavirus, influenza, bacterial pneumonia). We observed that COVID-19 and HLH share immunological pathways (cytokine/chemokine signaling and neutrophil-mediated immune responses), including gene signatures that stratify COVID-19 patients admitted to the intensive care unit (ICU) and COVID-19_nonICU patients. Of note, among the common differentially expressed genes (DEG), there is a cluster of neutrophil-associated genes that reflects a generalized hyperinflammatory state since it is also dysregulated in patients with KD and bacterial pneumonia. These genes are dysregulated at the protein level across several COVID-19 studies and form an interconnected network with differentially expressed plasma proteins that point to neutrophil hyperactivation in COVID-19 patients admitted to the intensive care unit. scRNAseq analysis indicated that these genes are specifically upregulated across different leukocyte populations, including lymphocyte subsets and immature neutrophils. Artificial intelligence modeling confirmed the strong association of these genes with COVID-19 severity. Thus, our work indicates putative therapeutic pathways for intervention.

Haemophagocytic lymphohistiocytosis (HLH)-associated stress cardiomyopathy secondary to autoimmune conditions successfully treated with anakinra.

We describe two young cases of reactive haemophagocytic lymphohistiocytosis (HLH) with the resultant stress cardiomyopathy in the setting of underlying autoimmune diseases, systemic lupus erythematosus (SLE) and Still's disease. The initial presentation was similar in both cases with fever, hyperinflammatory response, hypotension (vasoplegia), bicytopenia and hyperferritinemia. Despite standard of care and multiple broad-spectrum antibiotics, both cases remained pyrexic and were ultimately admitted to the intensive therapy unit to treat cardiogenic shock. Echocardiogram of both cases showed low ejection fraction, the cause for which was not found until the final diagnosis of HLH was made. Both cases made a complete clinical and cardiac recovery following the initiation of high-dose glucocorticoids and anakinra.

Cytokine storm after heart transplantation in COVID-19-related haemophagocytic lymphohistiocytosis (HLH).

While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection primarily causes inflammation in the respiratory system, there is growing evidence of extrapulmonary tissue damage mediated by the host innate immune system in children and adults. A cytokine storm can manifest as a viral-induced haemophagocytic lymphohistiocytosis (HLH). Here, we present a previously healthy 8-year-old boy with newly diagnosed cardiac injury and COVID-19-related HLH syndrome with haemophagocytosis in bone marrow biopsy. After remission of inflammation, the patient underwent a heart transplant due to persistent cardiac failure. The histology of the explanted heart showed only a focal subtle subendocardial inflammation. Three days after transplant, he developed progressive acute respiratory distress syndrome (ARDS) with the rise of inflammatory markers. He unfortunately died after 20 days because of disseminated intravascular coagulation (DIC). For the first time, we described a child with COVID-19-related HLH and severe cardiac failure, which had a poor prognosis despite a heart transplant.

Hemophagocytic syndrome secondary to SARS-Cov-2 infection: a case report.

BACKGROUND: Hemophagocytic syndrome (HPS) is a severe hyperinflammatory disease, whose diagnosis is based on the HLH-2004 criteria. In secondary forms of HLH (sHLH), the primary goal is treating the triggering factors such as COVID-19 (Coronavirus disease 2019). The link between the cytokine storm related to COVID-19 and development of sHLH has already been reported since the onset of pandemic, but little is known about clinical manifestations of HLH which develop after the patient's recovery from mild symptomatic or asymptomatic Sars-CoV-2 infection. CASE PRESENTATION: We describe the case of a woman diagnosed with sHLH related to previous Sars-CoV-2 infection and successfully treated with steroids, colchicine, etoposide and ruxolitinib. CONCLUSIONS: Our report suggests that HLH-like syndrome might be secondary to Sars-CoV-2 infection, even if the patient utterly recovered from the mildly symptomatic viral infection. In addition, we underline the treatment with low dose ruxolitinib plus etoposide as a potential choice for Sars-CoV-2 infection related HLH.

Haemophagocytic lymphohistiocytosis in an adult with postacute COVID-19 syndrome.

Haemophagocytic lymphohistiocytosis (HLH) causing multiorgan failure has been reported as an acute clinical presentation of COVID-19. However, the literature surrounding HLH in the context of a postacute COVID-19 syndrome is limited. This report presents a case of a life-threatening HLH occurring 6 weeks after a pauci-symptomatic COVID-19 infection in a previously healthy adult. A bone marrow aspirate confirmed the HLH and the patient was successfully treated with dexamethasone and etoposide. To our knowledge, this is the first case of HLH occurring as a postacute COVID-19 syndrome following a pauci-symptomatic initial infection.

Discrimination of COVID-19 From Inflammation-Induced Cytokine Storm Syndromes Using Disease-Related Blood Biomarkers.

OBJECTIVE: Infection with the novel coronavirus SARS-CoV-2 triggers severe illness with high mortality in a subgroup of patients. Such a critical course of COVID-19 is thought to be associated with the development of cytokine storm, a condition seen in macrophage activation syndrome (MAS) and secondary hemophagocytic lymphohistiocytosis (HLH). However, specific data demonstrating a clear association of cytokine storm with severe COVID-19 are still lacking. The aim of this study was to directly address whether immune activation in COVID-19 does indeed mimic the conditions found in these classic cytokine storm syndromes. METHODS: Levels of 22 biomarkers were quantified in serum samples from patients with COVID-19 (n = 30 patients, n = 83 longitudinal samples in total), patients with secondary HLH/MAS (n = 50), and healthy controls (n = 9). Measurements were performed using bead array assays and single-marker enzyme-linked immunosorbent assay. Serum biomarker levels were assessed for correlations with disease outcome. RESULTS: In patients with secondary HLH/MAS, we observed pronounced activation of the interleukin-18 (IL-18)-interferon-γ axis, increased serum levels of IL-1 receptor antagonist, intercellular adhesion molecule 1, and IL-8, and strongly reduced levels of soluble Fas ligand in the course of SARS-CoV-2 infection. These observations appeared to discriminate immune dysregulation in critical COVID-19 from the well-recognized characteristics of other cytokine storm syndromes. CONCLUSION: Serum biomarker profiles clearly separate COVID-19 from MAS or secondary HLH in terms of distinguishing the severe systemic hyperinflammation that occurs following SARS-CoV-2 infection. These findings could be useful in determining the efficacy of drugs targeting key molecules and pathways specifically associated with systemic cytokine storm conditions in the treatment of COVID-19.

Problems of Pathogenesis and Pathogenetic Therapy of COVID-19 from the Perspective of the General Theory of Pathological Systems (General Pathological Processes).

The COVID-19 pandemic examines not only the state of actual health care but also the state of fundamental medicine in various countries. Pro-inflammatory processes extend far beyond the classical concepts of inflammation. They manifest themselves in a variety of ways, beginning with extreme physiology, then allostasis at low-grade inflammation, and finally the shockogenic phenomenon of "inflammatory systemic microcirculation". The pathogenetic core of critical situations, including COVID-19, is this phenomenon. Microcirculatory abnormalities, on the other hand, lie at the heart of a specific type of general pathological process known as systemic inflammation (SI). Systemic inflammatory response, cytokine release, cytokine storm, and thrombo-inflammatory syndrome are all terms that refer to different aspects of SI. As a result, the metabolic syndrome model does not adequately reflect the pathophysiology of persistent low-grade systemic inflammation (ChSLGI). Diseases associated with ChSLGI, on the other hand, are risk factors for a severe COVID-19 course. The review examines the role of hypoxia, metabolic dysfunction, scavenger receptors, and pattern-recognition receptors, as well as the processes of the hemophagocytic syndrome, in the systemic alteration and development of SI in COVID-19.

Complicated case of COVID-19 disease with overlapping features of thrombotic thrombocytopenic purpura and haemophagocytic lymphohistiocytosis.

Haemophagocytic lymphohistiocytosis has been reported as an uncommon complication of severe COVID-19 disease while thrombotic thrombocytopenic purpura has been rarely reported. Here, we are reporting a 21-year-old man who developed a combination of these complications during the hospital stay in the post-COVID-19 recovery period. He presented with fever and bilateral COVID-19-related pneumonia requiring invasive ventilation. His hospital course was complicated by the development of pneumothorax, ventilator-associated pneumonia, thrombotic thrombocytopenic purpura and haemophagocytic lymphohistiocytosis. He received remdesivir, IVIG, steroid, fresh frozen plasma and supportive care but had a fatal outcome.

Case of haemophagocytic lymphohistiocytosis following Epstein-Barr virus infection.

Haemophagocytic lymphohistiocytosis (HLH) is a rare diagnosis that carries a high degree of mortality. We present this case of a previously healthy 22-year-old woman, who was admitted acutely ill to the hospital. One week prior, she had been seen by her primary care physician for fatigue and malaise. At that time, she was noted to have anterior and posterior cervical lymphadenopathy. She was referred to the emergency room and was diagnosed with acute Epstein-Barr virus (EBV) mononucleosis based on her clinical symptoms and positive heterophile antibody test. She was discharged after an uneventful 48-hour stay on the wards. She represented 7 days after discharge with cough, fatigue, nausea, vomiting, epigastric abdominal pain, diarrhoea, weight loss and subjective fevers. She had also reported haematemesis, epistaxis and melaena. Vital signs included temperature 36.9°C, blood pressure 90/50 mm Hg, heart rate 130 beats per minute and respiratory rate 32 breaths per minute. Physical examination was notable for an acutely ill appearing woman with scleral icterus, hepatosplenomegaly and palpable cervical and axillary lymphadenopathy. Complete blood count showed pancytopaenia with haemoglobin 59 g/L (normal 120-160 g/L), white blood cell count 2.7×109/L (normal 4-10.5×109/L) and platelet count 50×109/L (normal 150-450×109/L). The white blood cell count differential included 58% neutrophils (normal 38%-77%) with immature neutrophils in band form elevated at 45% (normal <14%), 16% lymphocytes (normal 20%-48%), 7% monocytes (normal <12%) and no eosinophils (normal <6%). Blood smear revealed anisocytosis, poikilocytosis and hypochromia. Coagulation panel showed elevated levels of d-dimer level at 1.39 µg/mL (normal <0.45 µg/mL), prolonged prothrombin time at 34.4 s (normal 11-15 s), prolonged activated partial thromboplastin time of 55.6 s (normal 25-34 s), prolonged international normalised ratio at 3.31 (normal <1.1) and low fibrinogen 60 mg/dL (normal >200 mg/dL). Lipid panel showed cholesterol at 114 mg/dL (normal 125-200 mg/dL), triglycerides 207 mg/dL (normal 30-150 mg/dL), high-density lipoprotein cholesterol 10 mg/dL (normal 40-60 mg/dL) and low-density lipoprotein cholesterol 63 mg/dL (normal <100 mg/dL). Other lab abnormalities included elevated ferritin of 6513 ng/mL (normal 10-150 ng/mL) and elevated lactate dehydrogenase of 1071 unit/L (normal 95-240 unit/L). Soluble interleukin-2 receptor alpha level was elevated at 60 727 units/mL (normal 223-710 units/mL). Fluorodeoxyglucose-positron emission tomography (FDG-PET) scan showed abnormal tracer localisation within the paratracheal, hilar, pelvic, abdominal and subcarinal lymph nodes, along with FDG-PET positive hepatosplenomegaly. A bone marrow biopsy showed hypercellular marrow (95% cellularity) with trilineage haematopoiesis, haemophagocytic cells, polytypic plasmacytosis and T-cell lymphocytosis, along with positive latent membrane protein-1 immunohistochemical staining for EBV. EBV quantitative DNA PCR showed >1 million copies. These findings were consistent with a diagnosis of HLH secondary to EBV infection. Despite intense therapy with the HLH-94 protocol, the patient expired from her illness after a prolonged hospital course.

A network-informed analysis of SARS-CoV-2 and hemophagocytic lymphohistiocytosis genes' interactions points to Neutrophil extracellular traps as mediators of thrombosis in COVID-19.

Abnormal coagulation and an increased risk of thrombosis are features of severe COVID-19, with parallels proposed with hemophagocytic lymphohistiocytosis (HLH), a life-threating condition associated with hyperinflammation. The presence of HLH was described in severely ill patients during the H1N1 influenza epidemic, presenting with pulmonary vascular thrombosis. We tested the hypothesis that genes causing primary HLH regulate pathways linking pulmonary thromboembolism to the presence of SARS-CoV-2 using novel network-informed computational algorithms. This approach led to the identification of Neutrophils Extracellular Traps (NETs) as plausible mediators of vascular thrombosis in severe COVID-19 in children and adults. Taken together, the network-informed analysis led us to propose the following model: the release of NETs in response to inflammatory signals acting in concert with SARS-CoV-2 damage the endothelium and direct platelet-activation promoting abnormal coagulation leading to serious complications of COVID-19. The underlying hypothesis is that genetic and/or environmental conditions that favor the release of NETs may predispose individuals to thrombotic complications of COVID-19 due to an increase risk of abnormal coagulation. This would be a common pathogenic mechanism in conditions including autoimmune/infectious diseases, hematologic and metabolic disorders.