Cytophagic histiocytic panniculitis and hemophagocytic lymphohistiocytosis: an overview

Corticosteroid-triggered acute skeletal muscle loss in lipodystrophy: A case report

The potential liability to hypercatabolism in lipodystrophy remains to be fully elucidated. Here we report a 28-year-old Japanese woman with acquired generalized lipodystrophy, who presented with recurrence of panniculitis and anemia. After corticosteroid treatment was started, she showed rapid reductions in body weight and lean mass by 15% at maximum, accompanied by an elevated urea nitrogen/creatinine ratio, which recovered almost fully as the corticosteroid treatment was tapered and discontinued. She had multiple risk factors for hypercatabolism: lack of metabolic reserves, insulin resistance, and hyperglycemia due to lipodystrophy, lowered daily activity due to anemia, persistent inflammation, and wasting associated with panniculitis, and relatively insufficient energy and protein intake during hospitalization. More attention should be paid to the potential liability to hypercatabolism in patients with lipodystrophy, and to skeletal muscle loss as an adverse effect of corticosteroid treatment in patients at high risk, such as those with diabetes or decreased metabolic reserves.

Clinicopathological Characteristics and Outcome of Cytophagic Histiocytic Panniculitis: A Single-Center, Retrospective Study

Background

Cytophagic histiocytic panniculitis (CHP) is a rare panniculitis associated with systemic features characterized by the infiltration of subcutaneous adipose tissue by benign-appearing T lymphocytes and phagocytic histiocytes, mimicking hemophagocytic lymphohistiocytosis (HLH) and subcutaneous panniculitis-like T-cell lymphoma (SPTCL).

Purpose

To establish the clinicopathological features and response to treatment of CHP and evaluate the prognosis of patients and guide therapy based on the current state of knowledge.

Material and Methods

Clinical, laboratory, histopathological, and outcome data of 12 patients with CHP were retrospectively collected between 2009 and 2022.

Results

All the patients presented with plaques or nodules, mostly located in the lower extremities (11/12). Fewer cases involved systemic symptoms (9/12) and laboratory abnormalities (6/12), and none were positive for serum Epstein-Barr virus (EBV)-DNA. Histopathological examination revealed mixed septal and lobular inflammatory infiltration of histiocytes and lymphocytes. Large or atypical lymphocytes were rarely present (2/12). In some patients, varying proportions of plasma cells, neutrophils, and eosinophils were observed. The extent of histocytophagy was mild (9/12), moderate (2/12), and severe (1/12). HLH was not observed in any of our cases, none of which were fatal.

Conclusion

The uniqueness of our study lies in the presence of neutrophil-rich dermal and subcutaneous infiltrates, associated with connective tissue disorders (CTD) and streptococcal infections. Our study reveals that EBV-negative CHP tends to a better prognosis than previously research, filling the gap in the much-needed details of CHP in the Chinese population. Moreover, CHP may present as a reactive process in combined primary diseases; further studies are required to validate these findings.

Panniculitis: A Cardinal Sign of Autoinflammation

Panniculitis was first described in the nineteenth century and is characterized by inflammation of the subcutaneous fat. It may be categorized in septal or lobular subtypes, but other histopathological features (e.g., presence of vasculitis, nature of inflammatory infiltrates, characteristics of fat necrosis) are also important for diagnostic purposes. Clinically, panniculitis is characterized by the presence of subcutaneous nodules, and both ulcerative and nonulcerative clinical subtypes have been proposed. In this review, we aimed to describe the occurrence of panniculitis in autoinflammatory disorders (AIDs) and related diseases. Among monogenic AIDs, panniculitis is common in IFN-mediated disorders. Panniculitis is a distinctive feature in proteasome-associated autoinflammatory syndromes (PRAAS), including chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome and Nakajo-Nishimura syndrome. On the other hand, erythema nodosum corresponds to the most common clinical form of panniculitis and is common in polygenic AIDs, such as Behçet's syndrome, inflammatory bowel disease, and sarcoidosis. Cytophagic histiocytic panniculitis, lipoatrophic panniculitis of children, and otulipenia are rare disorders that may also present with inflammation of the subcutaneous fat. Therefore, panniculitis can identify a specific subgroup of patients with AIDs and may potentially be regarded as a cardinal sign of autoinflammation.

Laboratory Features and Pathology of Cytokine Storm Syndromes

The laboratory diagnosis of cytokine storm syndromes (CSSs), i.e., hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS), is often challenging. The laboratory features using routinely available tests lack specificity, whereas confirmatory testing is available in only few laboratories in the United States. The disease mechanisms are still largely unclear, particularly in adults. In this chapter, the pathogenesis of CSSs, their associated laboratory findings, and recommended diagnostic strategies are reviewed.

Hemophagocytic Lymphohistiocytosis in the Context of Hematological Malignancies and Solid Tumors

Hemophagocytic lymphohistiocytosis (HLH) has been described for decades in association with malignancies (M-HLH). While its mechanism is unknown, M-HLH has a poor prognosis, ranging from 10% to 30% overall survival. Mature T-cell lymphomas, diffuse large B-cell lymphoma, and Hodgkin lymphoma, with or without viral co-triggers such as Epstein-Barr virus, are among the most frequent underlying entities. Most M-HLH cases occur at the presentation of malignancy, but they may also occur during therapy as a result of immune compromise from chemotherapy (HLH in the context of immune compromise, IC-HLH) and (typically) disordered response to infection or after immune-activating therapies (Rx-HLH, also known as cytokine release syndrome, CRS). IC-HLH typically occurs months after diagnosis in the context of fungal, bacterial, or viral infection, though it may occur without an apparent trigger. Rx-HLH can be associated with checkpoint blockade, chimeric antigen receptor T-cell therapy, or bispecific T-cell engaging therapy. Until recently, M-HLH diagnosis and treatment strategies were extrapolated from familial HLH (F-HLH), though optimized diagnostic and therapeutic treatment strategies are emerging.

Cytophagic Histiocytic Panniculitis Presenting as Subcutaneous Nodules and Generalized Edema - A Case Report

Background

Cytophagic histiocytic panniculitis (CHP) is a rare form of nodular panniculitis characterized by clinical manifestations such as skin erythema, nodules, fever, pancytopenia, liver failure, plasmacytosis, and hepatosplenomegaly. We report a case of CHP that was initially misdiagnosed as subcutaneous panniculitis-like T-cell lymphoma (SPTCL) but achieved complete remission with a favorable prognosis.

Methods

A 38-year-old female presented to the dermatology department with a 15-day history of subcutaneous nodules, generalized edema, and continuous fever.

Results

The patient was diagnosed as CHP combined with hemophagocytic syndrome by typical clinical manifestations, low value of SUVmax in positron emission tomography/computed tomography (PET/CT), benign differentiated T cells, negative TCR gene rearrangement, pancytopenia, abnormal coagulation, hypertriglyceridemia, decreased NK cell count, impaired liver function, and the presence of hemophagocytic cells observed in bone biopsy smears.

Conclusion

In our case, the patient presented with hemophagocytic syndrome with hemodynamic instability, indicating an intensive treatment is needed. The diagnosis of SPTCL necessitates a meticulous process of differential diagnosis, along with the cautious administration of an aggressive chemotherapy regimen. Extended follow-up is imperative to ascertain the long-term outcomes.

The pathophysiology and current treatments for the subcutaneous panniculitis-like T cell lymphoma: An updated review

Subcutaneous panniculitis-like T cell lymphoma (SPTCL) is a rare cutaneous T cell lymphoma, which is indolent in nature but could claim life if not correctly diagnosed and promptly treated. SPTCL is usually presented clinically as painless subcutaneous and erythematous nodules over the trunk or extremities. Active clinical vigilance for these subcutaneous nodules or panniculitis-like lesions is warranted. A biopsy must be performed in order to make a correct diagnosis. Positron emission tomography scan is utilized for disease staging and treatment follow-up. Due to the rarity of this lymphoma, a standard treatment protocol is not established yet. However, most cases of SPTCL could be treated well under immunosuppressive or polychemotherapeutic drugs except in cases with hemophagocytic syndrome. Hematopoietic stem cell transplantation may be used in refractory or relapse cases. In this review, we presented a case of SPTCL with long-term complete remission. Meanwhile, since most clinical evidences and experiences of SPTCL are based mostly on case reports or small case series, and the understanding of the SPTCL pathophysiology is limited, we reviewed and updated the pathophysiology and treatments of SPTCL.

[Ruxolitinib as an effective treatment for panniculitis associated hemophagocytic syndrome: A report of 2 cases and literature review]

Hemophagocytic syndrome (HPS) is a severe disease characterized by excessive release of inflammatory cytokines caused by abnormal activation of lymphocytes and macrophages, which can cause multiple organ damage and even death. Panniculitis is a disease characterized by inflammation of subcutaneous adipose tissue. We effectively treated 2 patients with panniculitis-associated HPS with ruxolitinib. Case 1: A 70-year-old male started with intermittent plantar swelling and pain, and then developed leukocytosis, mild anemia, multiple red maculopapules with painless subcutaneous nodules on the forehead, neck and bilateral lower legs. The patient was treated with prednisone and leflunomide for improvement. After that, repeated fever and rash occurred again. After admission to our hospital, we found his leukocyte and hemoglobin decreased, ferritin raised, fibrinogen and natural killer (NK) cell activity decreased, and hemophagocytic cells were found in bone marrow aspiration. The skin pathology was consistent with non-suppurative nodular panniculitis. He was diagnosed with nodular panniculitis associa-ted HPS. He was treated with glucocorticoid, cyclosporine, etoposide and gamma globule, but the disease was not completely controlled. After adjusting etoposide to ruxolitinib, his symptoms and abnormal laboratory findings returned to normal. After 2 months he stopped using ruxolitinib due to repeated infections. During the follow-up, though the prednisone dose was tapered, his condition was stable. Case 2: A 46-year-old female patient developed from intermittent fever, erythematous nodular rash with tenderness, leukopenia, and abnormal liver function. antibiotic therapy was ineffective. She improved after glucocorticoid treatment, and relapsed after glucocorticoid reduction. There were fever, limb nodules, erythema with ulcerative necrosis, intermittent abdominal pain when she came to our hospital. Blood examination showed that her white blood cells, red blood cells and platelets were decreased, fibrinogen was decreased, triglyceride was increased, ferritin and soluble interleukin-2 receptor(SIL-2R/sCD25) were significantly raised, and hemophagocytic cells were found in bone marrow aspiration. It was found that Epstein-Barr virus DNA was transiently positive, skin Staphylococcus aureus infection, and pulmonary Aspergillus flavus infection, but C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were normal, and no evidence of tumor and other infection was found. Skin pathology was considered panniculitis. The diagnosis was panniculitis, HPS and complicated infection. Antibiotic therapy and symptomatic blood transfusion were given first, but the disease was not controlled. Later, dexamethasone was given, and the condition improved, but the disease recurred after reducing the dose of dexamethasone. Due to the combination of multiple infections, the application of etoposide had a high risk of infection spread. Ruxolitinib, dexamethasone, and anti-infective therapy were given, and her condition remained stable after dexamethasone withdrawal. After 2 months of medication, she stopped using ruxolitinib. One week after stopping using ruxolitinib, she developed fever and died after 2 weeks of antibiotic therapy treatment in a local hospital. In conclusion, panniculitis and HPS are related in etiology, pathogenic mechanism and clinical manifestations. Abnormal activation of Janus-kinase and signal transduction activator of transcription pathway and abnormal release of inflammatory factors play an important role in the pathogenesis of the two diseases. The report suggests that ruxolitinib is effective and has broad prospects in the treatment of panniculitis associated HPS.

Cytophagic Histiocytic Panniculitis and Kikuchi-Fujimoto-Like Lymphadenitis in a Patient With Systemic Lupus Erythematosus

A 54-year-old African American male with systemic lupus erythematosus and chronic alcoholic hepatitis presented with recurrent fever, pancytopenia, transaminitis, weight loss, and widespread violaceous tender plaques. Skin biopsy revealed hemophagocytic histiocytes leading to a diagnosis of cytophagic histiocytic panniculitis in the setting of lupus panniculitis. During workup, an axillary lymph node biopsy mimicked Kikuchi-Fujimoto's disease. Treatment with tapering high-dose glucocorticoids, mycophenolate mofetil, and hydroxychloroquine induced remission of the disease. We believe the comorbid conditions of Kikuchi-Fujimoto-like pathology and cytophagic histiocytic panniculitis have not been documented in the literature to date in a patient with systemic lupus erythematosus.

Hemophagocytic Lymphohistiocytosis

CONTEXT.—

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder of immune regulation that can eventually result in end-organ damage and death. HLH is characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages that can lead to a cytokine storm. The diagnosis of HLH is often challenging due to the diverse clinical manifestations and the presence of several diagnostic mimics. The prognosis is generally poor, warranting rapid diagnosis and aggressive management.

OBJECTIVE.—

To provide a comprehensive review of the pathogenesis, clinical features, diagnosis, and management of HLH.

DATA SOURCES.—

Peer-reviewed literature.

CONCLUSIONS.—

HLH is a condition where a complete understanding of the pathogenesis, early diagnosis, and proper management has an important role in determining patient outcome. Genetic mutations causing impairment in the function of cytotoxic T lymphocytes and natural killer cells have been identified as the root cause of familial HLH; however, the specific pathogenesis of acquired HLH is unclear. The HLH-2004 protocol used in the diagnosis of HLH was originally developed for the pediatric population. The HLH-2004 protocol still forms the basis of the diagnosis of HLH in adults, although its use in adults has not been formally validated yet. Treatment of HLH is primarily based on the HLH-94 protocol, which involves suppressing the inflammatory response, but the treatment needs to be modified in adults depending on the underlying cause and comorbidities.

Ulcerative versus non-ulcerative panniculitis: is it time for a novel clinical approach to panniculitis?

Panniculitis, or inflammation of the fatty tissue, is an ongoing diagnostic challenge to both dermatologists and pathologists. The basis of the current panniculitis classification is histology, whether the inflammation is mainly located in the fibrovascular septa or in the adipose lobules thereafter with or without vasculitis. However, overall, the difficulty rises due to various terminologies and lack of clinical relevance with this classification. In addition to that, the majority of panniculitides have mixed infiltration of both lobular and septal and not a clear-cut distinction. The aim of this article is to provide a novel clinical algorithm to the diagnosis of panniculitis and thus to provide guidelines for all clinicians who may encounter this challenging condition in their clinical practice.

Anakinra Therapy for Non-cancer Inflammatory Diseases

Interleukin-1 (IL-1) is the prototypical inflammatory cytokine: two distinct ligands (IL-1α and IL-1β) bind the IL-1 type 1 receptor (IL-1R1) and induce a myriad of secondary inflammatory mediators, including prostaglandins, cytokines, and chemokines. IL-1α is constitutively present in endothelial and epithelial cells, whereas IL-1β is inducible in myeloid cells and released following cleavage by caspase-1. Over the past 30 years, IL-1-mediated inflammation has been established in a broad spectrum of diseases, ranging from rare autoinflammatory diseases to common conditions such as gout and rheumatoid arthritis (RA), type 2 diabetes, atherosclerosis, and acute myocardial infarction. Blocking IL-1 entered the clinical arena with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist (IL-1Ra); IL-1Ra prevents the binding of IL-1α as well as IL-1β to IL-1R1. Quenching IL-1-mediated inflammation prevents the detrimental consequences of tissue damage and organ dysfunction. Although anakinra is presently approved for the treatment of RA and cryopyrin-associated periodic syndromes, off-label use of anakinra far exceeds its approved indications. Dosing of 100 mg of anakinra subcutaneously provides clinically evident benefits within days and for some diseases, anakinra has been used daily for over 12 years. Compared to other biologics, anakinra has an unparalleled record of safety: opportunistic infections, particularly Mycobacterium tuberculosis, are rare even in populations at risk for reactivation of latent infections. Because of this excellent safety profile and relative short duration of action, anakinra can also be used as a diagnostic tool for undefined diseases mediated by IL-1. Although anakinra is presently in clinical trials to treat cancer, this review focuses on anakinra treatment of acute as well as chronic inflammatory diseases.

A case of deadly panniculitis

While the majority of panniculitides are benign in nature, there are rare instances when panniculitis presents as the initial sign of a complex disease state. We describe a case of panniculitis initially diagnosed as lupus profundus that was challenged when features of haemophagocytic lymphohistiocytosis became apparent. We illustrate how some key clinical features and newer investigations can help differentiate between benign and malignant panniculitis.

A systematic review of malignancy-associated hemophagocytic lymphohistiocytosis that needs more attentions

As an infrequent but potentially life-threatening hyperinflammatory syndrome, hemophagocytic lymphohistiocytosis (HLH) is clinically characterized with prolonged fever, hepatosplenomegaly, cytopenia, hypertriglyceridemia, hyperferritinemia and hemophagocytosis in bone marrow, liver, spleen or lymph nodes. Malignancy-associated HLH (M-HLH), one type of acquired HLH, usually presents variable overlaps of symptoms with other types of HLH, thus resulting in higher incidence of misdiagnosis and mortality. In recent years, with the increasing awareness to this disease, the diagnosis and management of HLH have gained more and more attention, and improvements have been made accordingly. As a result, the survival of patients is greatly prolonged. However, there is still no consensus on the diagnostic criteria and treatment strategies due to lack of large samples or prospective clinical trials. In order to improve recognition and diagnosis, and provide guidance regarding the treatment of M-HLH, the Study Group in HLH Subtypes of the Histiocyte Society has developed consensus recommendations for the diagnosis and management of M-HLH in 2015. In the present article, we summarized and discussed some updated understandings in M-HLH.

[Cutaneous panniculitis]

Panniculitis is an inflammation of the subcutaneous fat. Skin biopsy plays a critical role in the differential diagnosis of panniculitis. The most common approach to diagnosis relies on the differentiation between predominantly septal or lobular panniculitis, followed by the distinction between lesions with and without vasculitis. It is also very important to submit a part of the skin biopsy for microbiological analysis and for T-cell clonal expansion if T-cell lymphoma is suspected. Erythema nodosum, the most frequent septal panniculitis, has many causes and in its typical clinical presentation, does not require skin biopsy. In other panniculitis, diagnosis is based on the integration of the clinical and histological data, which renders a deep cutaneous biopsy necessary. Periarteritis nodosa, a septal panniculitis with vasculitis characterized by subcutaneous nodules and livedo racemosa, can be associated with systemic involvement. Nodular thrombophlebitis needs search for associated coagulopathy, Behçet's disease, periarteritis nodosa or Buerger's disease. Lobular panniculitis are classified according to the nature of cells present in the inflammatory infiltrate. If there is a lymphocytic infiltration, lupus panniculitis is difficult to differentiate from subcutaneous panniculitis-like T-cell lymphoma. If there are histiocytes, it can be a sarcoidosis, a cytophagic histiocytic panniculitis or, in newborn, a subcutaneous fat necrosis. Neutrophilic panniculitis needs careful clinic-pathologic correlation. Treatment of panniculitis can be challenging and is based on the histopathological findings. Frequently, the precise cause of panniculitis cannot be established from the outset, so it is important to follow-up patients and not hesitate to repeat the skin biopsy.

Consensus recommendations for the diagnosis and management of hemophagocytic lymphohistiocytosis associated with malignancies

The hyperinflammatory syndrome hemophagocytic lymphohistiocytosis can occur in the context of malignancies. Malignancy-triggered hemophagocytic lymphohistiocytosis should be regarded separately from hemophagocytic lymphohistiocytosis during chemotherapeutic treatment, which is frequently associated with an infectious trigger. The substantial overlap between the features of hemophagocytic lymphohistiocytosis with features of neoplasms makes its identification difficult when it occurs in malignant conditions. To facilitate recognition and diagnostic workup, and provide guidance regarding the treatment of malignancy-associated hemophagocytic lymphohistiocytosis, consensus recommendations were developed by the Study Group on Hemophagocytic Lymphohistiocytosis Subtypes of the Histiocyte Society, an interdisciplinary group consisting of pediatric and adult hemato-oncologists and immunologists.

An expanding role for interleukin-1 blockade from gout to cancer

There is an expanding role for interleukin (IL)-1 in diseases from gout to cancer. More than any other cytokine family, the IL-1 family is closely linked to innate inflammatory and immune responses. This linkage is because the cytoplasmic segment of all members of the IL-1 family of receptors contains a domain, which is highly homologous to the cytoplasmic domains of all toll-like receptors (TLRs). This domain, termed "toll IL-1 receptor (TIR) domain," signals as does the IL-1 receptors; therefore, inflammation due to the TLR and the IL-1 families is nearly the same. Fundamental responses such as the induction of cyclo-oxygenase type 2, increased surface expression of cellular adhesion molecules and increased gene expression of a broad number of inflammatory molecules characterizes IL-1 signal transduction as it does for TLR agonists. IL-1β is the most studied member of the IL-1 family because of its role in mediating autoinflammatory disease. However, a role for IL-1α in disease is being validated because of the availability of a neutralizing monoclonal antibody to human IL-1α. There are presently three approved therapies for blocking IL-1 activity. Anakinra is a recombinant form of the naturally occurring IL-1 receptor antagonist, which binds to the IL-1 receptor and prevents the binding of IL-1β as well as IL-1α. Rilonacept is a soluble decoy receptor that neutralizes primarily IL-1β but also IL-1α. Canakinumab is a human monoclonal antibody that neutralizes only IL-1β. Thus, a causal or significant contributing role can be established for IL-1β and IL-1α in human disease.

Hemophagocytic syndromes--an update

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome and not an independent disease. HLH represents the extreme end of a severe uncontrolled hyperinflammatory reaction that can occur in many underlying conditions. Genetic forms of HLHs are due to defects in transport, processing and function of cytotoxic granules in natural killer cells and cytotoxic T lymphocytes, and are not restricted to manifestation in childhood. Acquired forms of HLH are encountered in infections, autoinflammatory and autoimmune diseases, malignancies, acquired immune deficiency. Functional tests allow for differentiation between genetic and acquired HLH. Treatment aims at suppressing hypercytokinemia and eliminating activated and infected cells. It includes immunomodulatory and immunosuppressive agents, cytostatics, T-cell and cytokine antibodies. In genetic HLH cure can only be achieved with hematopoietic stem cell transplantation. Reduced-intensity conditioning regimens have considerably improved survival.

Cytophagic histiocytic panniculitis, hemophagocytic lymphohistiocytosis and undetermined autoimmune disorder: reconciling the puzzle

Cytophagic histiocytic panniculitis is a rare disease, associated with either nonmalignant conditions or subcutaneous panniculitis-like T-cell lymphoma, and often also associated with hemophagocytic lymphohistiocytosis (HLH). We report the case of a 11-year-old boy with a history of secondary HLH who, after a local trauma, developed a painful, indurated plaque over the right thigh associated with relapsing HLH. Histopathologic findings from skin biopsy specimens revealed significant lobular panniculitis with benign histiocytes showing hemophagocytosis. High-dose intravenous methylprednisolone and cyclosporine A treatment was highly effective. A genetic study after a new, relapsing episode of HLH revealed an heterozygous missense mutation on STX 11 gene inherited from the mother.

Treating inflammation by blocking interleukin-1 in humans

IL-1 is a master cytokine of local and systemic inflammation. With the availability of specific IL-1 targeting therapies, a broadening list of diseases has revealed the pathologic role of IL-1-mediated inflammation. Although IL-1, either IL-1α or IL-1β, was administered to patients in order to improve bone marrow function or increase host immune responses to cancer, these patients experienced unacceptable toxicity with fever, anorexia, myalgias, arthralgias, fatigue, gastrointestinal upset and sleep disturbances; frank hypotension occurred. Thus it was not unexpected that specific pharmacological blockade of IL-1 activity in inflammatory diseases would be beneficial. Monotherapy blocking IL-1 activity in a broad spectrum of inflammatory syndromes results in a rapid and sustained reduction in disease severity. In common conditions such as heart failure and gout arthritis, IL-1 blockade can be effective therapy. Three IL-1blockers have been approved: the IL-1 receptor antagonist, anakinra, blocks the IL-1 receptor and therefore reduces the activity of IL-1α and IL-1β. A soluble decoy receptor, rilonacept, and a neutralizing monoclonal anti-interleukin-1β antibody, canakinumab, are also approved. A monoclonal antibody directed against the IL-1 receptor and a neutralizing anti-IL-1α are in clinical trials. By specifically blocking IL-1, we have learned a great deal about the role of this cytokine in inflammation but equally important, reducing IL-1 activity has lifted the burden of disease for many patients.

Hemophagocytic lymphohistiocytosis: an update on diagnosis and pathogenesis

Hemophagocytic lymphohistiocytosis (HLH) is a frequently fatal and likely underdiagnosed disease involving a final common pathway of hypercytokinemia, which can result in end-organ damage and death. Although an early diagnosis is crucial to decrease mortality, the definitive diagnosis is often challenging because of the lack of specificity of currently accepted diagnostic criteria and the absence of confirmatory gold standards. Because of the wide range of laboratory assays involved in the diagnosis of HLH, practicing pathologists from a broad spectrum of clinical specialties need to be aware of the disease so that they may appropriately flag results and convey them to their clinical counterparts. Our article summarizes these new advances in the diagnosis of HLH and includes a review of clinical findings, updated understanding of the pathogenesis, and promising new testing methods.

Systemic lupus erythematosus with cytophagic histiocytic panniculitis successfully treated with high-dose glucocorticoids and cyclosporine A

A 37-year-old male with systemic lupus erythematosus (SLE) presented with high fever, subcutaneous indurations, anemia, thrombocytopenia, elevated liver enzymes and hyperferritinemia. Skin biopsy revealed hemophagocytic histiocytes in the adipose tissues. The patient was diagnosed with SLE with cytophagic histiocytic panniculitis (CHP). Treatment with high-dose glucocorticoids and cyclosporine A induced remission of SLE and CHP.

CHP is generally a systemic disorder affecting subcutaneous adipose tissues with a high mortality rate. However, based on the present and previously reported cases, we believe that intensive immunosuppression can ameliorate CHP that occurs as a skin manifestation of SLE.

Treating inflammation by blocking interleukin-1 in a broad spectrum of diseases

Interleukin-1 (IL-1) is a highly active pro-inflammatory cytokine that lowers pain thresholds and damages tissues. Monotherapy blocking IL-1 activity in autoinflammatory syndromes results in a rapid and sustained reduction in disease severity, including reversal of inflammation-mediated loss of sight, hearing and organ function. This approach can therefore be effective in treating common conditions such as post-infarction heart failure, and trials targeting a broad spectrum of new indications are underway. So far, three IL-1-targeted agents have been approved: the IL-1 receptor antagonist anakinra, the soluble decoy receptor rilonacept and the neutralizing monoclonal anti-IL-1β antibody canakinumab. In addition, a monoclonal antibody directed against the IL-1 receptor and a neutralizing anti-IL-1α antibody are in clinical trials.

A clinical perspective of IL-1β as the gatekeeper of inflammation

An expanding spectrum of acute and chronic non-infectious inflammatory diseases is uniquely responsive to IL-1β neutralization. IL-1β-mediated diseases are often called "auto-inflammatory" and the dominant finding is the release of the active form of IL-1β driven by endogenous molecules acting on the monocyte/macrophage. IL-1β activity is tightly controlled and requires the conversion of the primary transcript, the inactive IL-1β precursor, to the active cytokine by limited proteolysis. Limited proteolysis can take place extracellularly by serine proteases, released in particular by infiltrating neutrophils or intracellularly by the cysteine protease caspase-1. Therefore, blocking IL-1β resolves inflammation regardless of how the cytokine is released from the cell or how the precursor is cleaved. Endogenous stimulants such as oxidized fatty acids and lipoproteins, high glucose concentrations, uric acid crystals, activated complement, contents of necrotic cells, and cytokines, particularly IL-1 itself, induce the synthesis of the inactive IL-1β precursor, which awaits processing to the active form. Although bursts of IL-1β precipitate acute attacks of systemic or local inflammation, IL-1β also contributes to several chronic diseases. For example, ischemic injury, such as myocardial infarction or stroke, causes acute and extensive damage, and slowly progressive inflammatory processes take place in atherosclerosis, type 2 diabetes, osteoarthritis and smoldering myeloma. Evidence for the involvement of IL-1β and the clinical results of reducing IL-1β activity in this broad spectrum of inflammatory diseases are the focus of this review.