Search Results (63)

Background: Visceral Leishmaniasis (VL), a severe systemic parasitic disease caused by Leishmania species, can be complicated by secondary Hemophagocytic Lymphohistiocytosis (HLH). HLH is a life-threatening hyperinflammatory syndrome characterized by excessive immune activation that results in multiorgan dysfunction. The co-occurrence of VL and HLH in adults is a rare but critical diagnostic and therapeutic challenge, often leading to fatal outcomes if treatment is delayed. Case Presentation: We present two cases of adult males (60 and 72 years old) from Greece, an endemic area for L. infantum, who presented with prolonged fever, pancytopenia, hepatosplenomegaly, and impaired liver function. Both patients exhibited extremely elevated ferritin (all > 2000 ng/mL and one > 20,000 ng/mL) and hypertriglyceridemia, fulfilling key laboratory criteria for HLH. Diagnosis was confirmed by the visualization of Leishmania amastigotes in bone marrow aspirates, which also demonstrated features of hemophagocytosis. Case 1, critically ill with acute kidney injury and coagulopathy, required combined treatment with liposomal Amphotericin B and immunoglobulin therapy for HLH. Case 2, who showed rapid and “spectacular improvement” solely after receiving liposomal Amphotericin B, did not require HLH-specific immunosuppression. Conclusions: VL-associated HLH should be considered in adult patients presenting with complex systemic inflammation, fever, and cytopenias, particularly in endemic settings. Our cases illustrate that the prompt initiation of anti-leishmanial therapy with liposomal Amphotericin B can be sufficient to reverse the HLH syndrome by eliminating the infectious trigger. However, intensive immunomodulation may be necessary in patients presenting with critical multi-organ failure. Full article

Background and Clinical Significance: Immune checkpoint inhibitors (ICIs) have transformed the management of advanced solid tumors but can trigger severe immune-related adverse events (irAEs). Among the rarest and most life-threatening is hemophagocytic lymphohistiocytosis (HLH), a hyperinflammatory syndrome driven by uncontrolled immune activation. Case Presentation: We report the case of an 80-year-old man with clear cell renal carcinoma with sarcomatoid features who developed secondary hemophagocytic lymphohistiocytosis (HLH) after receiving four cycles of adjuvant pembrolizumab therapy. Following four cycles of immunotherapy, he presented with persistent fever, pancytopenia, hyperferritinemia (>49,000 ng/mL), hypofibrinogenemia, and elevated soluble IL-2 receptor (>7500 U/mL), fulfilling at least five HLH-2004 diagnostic criteria. Despite treatment with high-dose corticosteroids and intravenous anakinra (100 mg every 6 h), his condition rapidly deteriorated, leading to multiorgan failure and death. Discussion: ICI-induced HLH is an exceptional but increasingly recognized irAE, with fewer than 30 pembrolizumab-related cases reported to date. Diagnosis is challenging due to its nonspecific presentation, which can mimic infection, hepatic toxicity, or disease progression. The pathogenesis is believed to involve excessive activation of cytotoxic T cells and cytokine storm. While established pediatric protocols (HLH-94, HLH-2004) guide management, adult cases often require individualized approaches using corticosteroids and cytokine-targeted therapies such as IL-1 or IL-6 blockade. Conclusions: HLH secondary to ICIs should be considered in the differential diagnosis of patients receiving immunotherapy who develop unexplained fever and cytopenia. Early recognition and prompt initiation of immunosuppressive therapy are critical to improving outcomes in this potentially fatal complication. Full article

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening hyperinflammatory syndrome characterized by uncontrolled macrophage activation. Secondary HLH is more common in adults and may be triggered by infection, malignancy, or autoimmune disease. Dyslipidemia, particularly hypolipoproteinemia, has been described but remains underexplored. Methods: We retrospectively reviewed 18 adult HLH cases diagnosed between 2012 and 2020 at two institutions where complete lipid profiles were obtained at or near diagnosis. HLH was defined according to HLH-2004 criteria. Results: Among 18 patients, 17 (94%) had secondary HLH, most commonly idiopathic (n = 5, 28%) or Epstein–Barr virus-associated (n = 3, 17%). Hypolipidemia was nearly universal: all (18/18) had HDL-C < 30 mg/dL, 15/18 (83%) had HDL-C < 20 mg/dL, and 12/18 (67%) had HDL-C < 10 mg/dL. LDL-C was <100 mg/dL in 12/18 (67%), with 6/18 (33%) undetectable. Triglycerides were variably elevated (median 279 mg/dL, range 96–1658 mg/dL). Three representative cases with profound hypolipoproteinemia demonstrated lipid normalization after HLH-directed therapy. Conclusions: Severe reductions in HDL-C and LDL-C appear to accompany HLH and may contribute to its pathophysiology by impairing antioxidant defenses, destabilizing membranes, and potentiating macrophage activation. This case series highlights a consistent association between hypolipoproteinemia and HLH, suggesting potential diagnostic value. However, the observational design and small cohort limit generalizability. Larger prospective studies are needed to clarify mechanisms and evaluate whether full lipid profiling should be incorporated into diagnostic algorithms. Full article

Macrophage activation syndrome (MAS), a hyperinflammatory condition driven by uncontrolled immune activation, is widely recognized as a critical complication in pediatric septic shock. This syndrome shares pathophysiological features with hemophagocytic lymphohistiocytosis (HLH) and other cytokine storm syndromes, and it contributes to significant morbidity and mortality in pediatric and adult patients. Hyperferritinemia—a hallmark of MAS—is not only a diagnostic clue but also a prognostic marker for poor outcomes in sepsis. High ferritin levels are strongly suggestive of MAS, yet even moderate elevations in combination with the trend of ferritin levels can be indicative of heightened mortality risk. Distinguishing MAS from severe sepsis or other hyperinflammatory syndromes in children (such as multisystem inflammatory syndrome in children (MIS-C)) can be challenging, as clinical features often overlap. However, early recognition and timely immunomodulatory therapy, particularly corticosteroids and targeted biologic agents, can be life-saving. Recent advances emphasize a syndromic approach to diagnosing MAS within the spectrum of hyperferritinemic sepsis, using scoring tools or MAS-specific criteria adapted to sepsis or MIS-C contexts. Ongoing studies aim to refine biomarker-based stratification and therapeutic algorithms. This review synthesizes current knowledge on MAS as a complication of sepsis, including the diagnostic importance of ferritin levels, differential diagnosis with other cytokine storm syndromes, and the latest therapeutic approaches. It underscores the importance of early suspicion and intervention to reverse immune dysregulation and improve outcomes in critically ill pediatric patients. Full article

At onset, myelodysplastic syndrome (MDS) may be complicated by coagulation and fibrinolytic abnormalities, such as disseminated intravascular coagulation (DIC), tumor lysis syndrome (TLS), infection, thromboembolism, hemophagocytic syndrome/hemophagocytic lymphohistiocytosis (HPS/HLH), hemorrhage, and hematoma formation. In these cases, the cause may be secondary. On the other hand, it is known that platelet clotting dysfunction and fibrinolysis abnormalities are seen in the background of MDS, and primary fibrinolysis abnormalities may be complicated by adverse events associated with paraneoplastic syndrome (PNS). Coagulation fibrinolysis, as a PNS associated with MDS, is known to take the pattern of either consumptive coagulation abnormality or fibrinolytic coagulation abnormality. One mechanism of coagulation and fibrinolytic abnormalities has been shown to be the immunophenotypical pathway, and aberrant cytokine production is also associated with coagulopathy in MDS. We focused on how to differentiate an MDS-associated bleeding tendency resulting from either secondary or primary causes. In order to make this differentiation, we proposed a useful flowchart for the differentiation of solidified fibrinolysis seen at the initial MDS diagnosis. Additionally, we compared and summarized the molecular pathways of the secondary and primary causes of coagulopathy. Addressing coagulation and fibrinolytic abnormalities in MDS is required to differentiate the complexity and heterogeneity of bleeding and coagulation abnormalities. This review highlights the need to distinguish between the primary (disease-intrinsic) and secondary (reactive or complication-related) causes of coagulopathy. By proposing a diagnostic flowchart tailored to evaluate these causes at initial diagnosis, this study supports individualized risk stratification and management strategies. By comparing the molecular pathways of the two causes of coagulopathy, we provide a clinical discussion of the underlying pathologies. This aligns with the principles of personalized medicine by ensuring that treatment decisions (e.g., supportive care, anticoagulation, and antifibrinolytics) are based on the patient’s specific pathophysiological profile, rather than a one-size-fits-all approach. Full article

Chimeric antigen receptor (CAR) T-cell infusion has led to improved outcomes in patients with B-lymphoblastic leukemia, B-cell lymphoma, and multiple myeloma. The spectrum of post-CAR T-cell hematolymphoid abnormalities is expanding, although they remain under-recognized. Pathologists play a key role in characterizing hematolymphoid proliferation after CAR T-cell therapy. This review presents clinical and pathologic findings of common hematolymphoid proliferation after CAR T-cell therapy, illustrated by selected cases. A review of the literature is presented in the context of individual cases, and our current understanding of the pathomechanism is discussed. Infused CAR T-cells undergo a series of four phases: distribution, expansion, contraction, and persistence. In the expansion phase, transient peripheral blood lymphocytosis occurs, reaching a peak two weeks post-infusion. Delayed contraction of CAR T-cells may give rise to hemophagocytic lymphohistiocytosis-like syndrome. Immune effector cell-associated enterocolitis presents in the persistence phase, about 3–6 months after infusion. Pathologic findings include a T-cell infiltrate in the intestinal mucosa and changes resembling graft versus host disease (GVHD). This entity requires differentiation from infections and from T-cell neoplasms, including those derived from CAR T-cells. Secondary myeloid malignancies follow the same pathways as therapy-related myeloid neoplasm but present with a shorter median latency. It is essential for pathologists to recognize post-CAR T-cell hematolymphoid proliferation to support clinical decision making in a high-risk patient population. Full article

Sickle cell disease (SCD) is a hereditary hemoglobin disorder characterized by chronic hemolysis and recurrent vaso-occlusive crises, leading to a wide spectrum of complications. While common SCD manifestations have well-established management protocols, rare and atypical complications pose significant diagnostic and therapeutic challenges. A critical barrier is diagnostic overshadowing, where common SCD symptoms (pain, fever, respiratory distress) mask infrequent but life-threatening conditions, resulting in delayed recognition and suboptimal outcomes. This narrative review synthesizes the literature from 2000–2025 on rare SCD complications, including atypical neurological events (e.g., spontaneous epidural or subdural hematoma, central retinal artery occlusion, cerebral arteriovenous malformations, posterior reversible encephalopathy syndrome), uncommon hematologic syndromes (acute leukemia, extramedullary hematopoiesis in unusual sites, hemophagocytic lymphohistiocytosis), severe cardiopulmonary emergencies (acute multiorgan failure and fat embolism syndromes), unusual hepatic crises (acute hepatic sequestration, intrahepatic cholestasis), and others (e.g., compartment syndrome). Key insights underscore the need for high clinical suspicion and prompt use of advanced diagnostics (e.g., MRI, specialized laboratory tests) when patients present with atypical or disproportionate symptoms. Clinical implications: Heightening clinician awareness of these rare complications and implementing structured diagnostic strategies can facilitate earlier intervention, improving outcomes and reducing the high morbidity and mortality associated with these infrequent but severe events. Full article

Sweet syndrome (SS) is a rare neutrophilic dermatosis often associated with hematologic malignancies, particularly myelodysplastic syndromes (MDSs). We report a case of SS-like dermatosis in a patient with MDS who subsequently developed peripheral T-cell non-Hodgkin lymphoma (NHL). We review the literature on Sweet syndrome to contextualize this atypical presentation Methods: We present a case report of a 77-year-old male with leukopenia and known MDS, admitted for a persistent, infiltrated erythematous eruption. The patient underwent repeated dermatologic assessments, and serial skin and bone marrow biopsies with histopathologic and immunohistochemical analysis. A literature review was also conducted, focusing on SS in association with hematologic malignancies, including T-cell NHL. Results: Initial skin biopsies were inconclusive, and SS was diagnosed clinically based on lesion morphology and a prompt response to corticosteroids, despite the absence of definitive neutrophilic infiltrates. During follow-up, the patient’s condition progressed with worsening cytopenias and recurrent febrile episodes. Repeat biopsies eventually confirmed the diagnosis of peripheral T-cell NHL with secondary hemophagocytic lymphohistiocytosis (HLH). Conclusions: This case illustrates the diagnostic uncertainty of SS-like eruptions in hematologic patients when histopathological findings are atypical or absent. Corticosteroid responsiveness may guide early diagnosis. Full article

Severe COVID-19 infection resulting in hospitalization shares features with cytokine storm syndromes (CSSs) such as hemophagocytic lymphohistiocytosis (HLH). Various published criteria were explored to define CSS among patients (n = 32) enrolled in a COVID-19 clinical trial. None of the patients met HLH-04 or HScore criteria, but the ferritin to erythrocyte sedimentation rate (ferritin–ESR) ratio and the COVID-19 cytokine storm score (CSs) identified 84% and 81% of patients, respectively. As 30–40% of patients in published secondary HLH cohorts possess rare heterozygous mutations in familial HLH (fHLH) genes, whole genome sequencing was undertaken to explore immunologic gene mutation associations among 20 patients enrolled in the trial. Rare mutations in fHLH genes were identified in 6 patients (30%), and 4 patients (20%) possessed rare mutations in DOCK8 (a novel CSS gene). Foamy viral transduction of the 3 DOCK8 missense mutations into NK-92 natural killer (NK) cells diminished NK cell cytolytic function, a feature of HLH. This severe COVID-19 cohort, like others, shares CSS features but is best identified by the ferritin–ESR ratio. Rare heterozygous CSS gene (fHLH genes and DOCK8) mutations were frequently (45%) identified in this severe COVID-19 cohort, and DOCK8 missense mutations may contribute to CSS via diminished lymphocyte cytolytic activity. Full article

Background and Clinical Significance: Hemophagocytic lymphohistiocytosis (HLH) and autoimmune hemolytic anemia (AIHA) are both life-threatening hematologic syndromes that rarely present together outside of malignancy. Advanced acquired immunodeficiency syndrome (AIDS) creates a milieu of profound immune dysregulation and hyperinflammation, predisposing patients to atypical overlaps of these disorders. Case Presentation: A 30-year-old woman with poorly controlled AIDS presented with three weeks of jaundice, fever, and fatigue. Initial labs revealed pancytopenia, hyperbilirubinemia, and elevated ferritin level. Direct anti-globulin testing confirmed warm AIHA (IgG⁺/C3d⁺) with transient cold agglutinins. Despite intravenous immunoglobulin (IVIG), rituximab, and transfusions, she developed hepatosplenomegaly, extreme hyperferritinemia, and sIL-2R > 10,000 pg/mL, meeting HLH-2004 criteria. Bone marrow biopsy excluded malignancy; further work-up revealed Epstein–Barr virus (EBV) viremia and cytomegalovirus (CMV) reactivation. Dexamethasone plus reduced-dose etoposide transiently reduced soluble interleukin-2 receptor (sIL-2R) but precipitated profound pancytopenia, Acute respiratory distress syndrome (ARDS) from CMV/parainfluenza pneumonia, bilateral deep vein thrombosis (DVT), and an ST-elevation myocardial infarction (STEMI). She ultimately died of hemorrhagic shock after anticoagulation despite maximal supportive measures. Conclusions: This case underscores the diagnostic challenges of HLH-AIHA overlap in AIDS, where cytopenias and hyperferritinemia mask the underlying cytokine storm. Pathogenesis likely involved IL-6/IFN-γ overproduction, impaired cytotoxic T-cell function, and molecular mimicry. While etoposide remains a cornerstone of HLH therapy, its myelotoxicity proved catastrophic in this immunocompromised host, highlighting the urgent need for cytokine-targeted agents to mitigate treatment-related mortality. Full article

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome that may be triggered by infections such as dengue virus. Due to overlapping features with severe dengue and sepsis, diagnosis of HLH in dengue-infected patients remains challenging. Methods: We conducted a narrative review and individual patient data meta-analysis of published cases of dengue-associated HLH. Eligible studies were identified through a search of PubMed and Scopus databases up to 5 March 2025. Clinical, laboratory, microbiological, treatment, and outcome data were extracted and analyzed. Results: A total of 133 patients from 71 studies were included. The median patient age was 18 years, and 56.8% were male. Common clinical features included fever (96.9%), cytopenias, organomegaly, and liver dysfunction. ALT elevation, jaundice, and hypofibrinogenemia were associated with mortality. DENV-1 was the most common serotype (57.4%) and was negatively associated with death. Overall, 19.3% of patients died. Multivariate analysis did not identify independent mortality predictors. Conclusions: Dengue-associated HLH predominantly affects young individuals and carries significant mortality. Key indicators of poor prognosis include hepatic dysfunction and the presence of shock or organ failure. Early recognition and prompt immunomodulatory treatment, particularly corticosteroids, may improve outcomes. Full article

Macrophage activation syndrome (MAS) is a complex, life-threatening, hyperinflammatory condition occurring as a form of hemophagocytic lymphohistiocytosis (HLH), commonly associated with several autoimmune and autoinflammatory diseases, and certain infections such as Parvovirus B19 (P19V). The onset of systemic lupus erythematosus (SLE) presenting as MAS during pregnancy is uncommon, posing significant diagnostic and therapeutic challenges. We present a case of a 30-year-old woman at the 12th gestational week with fever, arthralgia, rash, cervical lymphadenopathy, cytopenia, and elevated liver enzyme. Bone marrow biopsy revealing hemophagocytosis, elevated ferritin and triglycerides, high interleukin-2, fever and cytopenia, confirmed the diagnosis of HLH. Further evaluation revealed the diagnosis of SLE. Treatment was initiated with intravenous immunoglobulin and corticosteroids. Given the deterioration in the patient’s clinical condition, a decision was made to terminate the pregnancy. She continued in the following months to receive SLE treatment with corticosteroids, cyclophosphamide, hydroxychloroquine, and later with mycophenolate mofetil due to the development of Class IV of lupus nephritis. P19V IgM antibodies were initially positive, later seroconverted to IgG, indicating that infection may have acted as a trigger for the onset of SLE and MAS development during pregnancy. The overlapping clinical features of P19V infection, SLE, and MAS pose significant diagnostic and therapeutic challenges. Early recognition and comprehensive diagnostic evaluation are crucial for the management of these conditions, especially during pregnancy, where both maternal outcomes are at risk. Full article

Background and Objectives: Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory condition characterized by excessive activation of cytotoxic lymphocytes and macrophages, resulting in a cytokine storm, multiorgan damage, and high mortality. HLH is classified into primary (genetic) and secondary (acquired) forms, with diagnosis often challenging due to nonspecific symptoms. Macrophage activation syndrome (MAS) refers to the secondary HLH triggered by rheumatic diseases. In this study, we retrospectively analyzed the clinical and laboratory features of patients with secondary HLH to enhance understanding of this life-threatening condition and summarize emerging management strategies. Materials and Methods: This single-center retrospective study analyzed medical records of patients hospitalized with HLH at the University Hospital in Kraków, Poland, from 2013 to 2024, based on HLH-2009 criteria and HScore > 169 points. Diagnostic criteria included clinical, laboratory, and histological findings, e.g., hemophagocytosis in bone marrow, circulating cytopenia, and elevated ferritin levels. Results: A total of 21 patients met the criteria for HLH diagnosis, with a median age of 35 (range: 19–67) years, including 12 women (57.1%). The median HScore among the patients was 244 (range: 208–304) points. Fever was the most common presenting symptom, occurring in all cases. High ferritin, hypertriglyceridemia, and hypofibrinogenemia in peripheral blood were also prevalent. Bone marrow hemophagocytosis was confirmed in 66.7% of cases (n = 12/18 of available data). Regarding immunosuppressive therapy, glucocorticosteroids were the most frequently used (used in all cases). Four (19.0%) patients died during HLH (cases triggered by lymphoma [twice], Epstein–Barr virus infection, unknown reason). Compared to survivors, these patients had lower counts of white blood cells, neutrophils, and lymphocytes at diagnosis (p < 0.05 for all). Conclusions: Secondary HLH is a severe syndrome requiring rapid diagnosis and timely intervention to improve patient outcomes. Lower white blood cell, neutrophil, and lymphocyte counts present worse prognostic factors. Full article

Background: Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal syndrome of immune dysregulation with primary (genetic) and secondary (acquired) forms, including malignancy-associated HLH (m-HLH). The condition often presents significant diagnostic and therapeutic challenges due to overlapping symptoms with underlying malignancies and the absence of standardized guidelines for refractory cases. The established standard of care is dexamethasone and etoposide, but no guidelines exist for refractory HLH or cases triggered by malignancy. Case presentations: This case series describes three adolescent patients with m-HLH, focusing on complexities in diagnosis, treatment regimens, and toxicity management. While dexamethasone and etoposide remain a standard of care, their efficacy in refractory cases is limited. We highlight the novel use of targeted therapies, including emapalumab, an interferon-gamma inhibitor, and ruxolitinib, a JAK1/2 inhibitor, which showed potential in modulating immune hyperactivation. Conclusions: Our findings emphasize the need for individualized treatment approaches in adolescent m-HLH and importance of further research to establish evidence-based therapeutic guidelines for refractory cases. Full article

Background: Critically ill patients often display systemic immune dysregulation and increased inflammatory activity. Hemophagocytic lymphohistiocytosis (HLH) represents a rare syndrome defined by the inappropriate survival of cytotoxic T cells and the occurrence of cytokine storms. Although HLH is characterized by relatively high mortality rates, little is known about the predictive value of its diagnostic criteria. Accordingly, our objective was to evaluate these properties within an unselected cohort of critically ill patients admitted to a tertiary intensive care unit (ICU). Methods: This single-center prospective observational study included 176 consecutive patients. Available HLH criteria at admission were assessed, including sCD25 measurements performed using ELISA. Results: Overall, 30-day mortality rates were significantly higher in patients exhibiting two or more criteria of HLH (21.9% vs. 43.3%, p = 0.033). Moreover, sCD25 emerged as an independent risk predictor of 30-day mortality independent of age, sex, the use of vasopressors, and mechanical ventilation (HR 2.72 for the highest tertile vs. lowest tertile, p = 0.012). Additionally, fibrinogen was significantly decreased in non-survivors (p = 0.019), and its addition to the SAPS II score significantly increased its prognostic capability (p = 0.045). In contrast, ferritin and triglyceride levels were not different in survivors versus non-survivors. Conclusions: Critically ill patients displaying two or more HLH criteria exhibit a dramatic increase in 30-day mortality, even in the absence of an established HLH diagnosis. Furthermore, elevated levels of sCD25 and decreased levels of fibrinogen were found to be significant predictors of mortality. Full article