Multicentric Castleman's disease treated with antivirals and immunosuppressants

Human Herpesvirus-8 (HHV-8)-Positive Human Immunodeficiency Virus (HIV)-Negative Multicentric Castleman Disease With a Fulminant Course

Multicentric Castleman disease (MCD) is a poorly understood, heterogeneous lymphoproliferative disorder with benign hyperplastic lymph nodes and systemic inflammatory symptoms. Human herpesvirus-8 (HHV-8) may be associated with MCD, whether or not the patient is infected with the human immunodeficiency virus (HIV). A 74-year-old man presented with anaemia, thrombocytopenia and bilateral axillary adenomegaly of unknown origin. The patient was admitted to the hospital two years ago with clinical signs of weight loss, asthenia, anorexia and a maculopapular rash on the trunk and back. Blood analysis showed pancytopenia (haemoglobin 7.7 g/dL, leucocytes 2.55 x 109/L and platelets 41 x 109/L), elevated acute phase reactants (such as C-reactive protein, erythrocyte sedimentation rate, ferritin and fibrinogen), hypoalbuminemia and hypergammaglobulinemia, and HIV serology was negative. Thoracic, abdominal and pelvic axial tomography showed generalised lymphadenopathy. The bone marrow biopsy showed only reactive changes, and the histology of an excisional biopsy of the adenopathy was consistent with the plasmablastic variant of MCD associated with HHV-8. The HHV-8 viral load was 3.8 x 104 copies/mL (4.5 log). He was started on prednisolone 60 mg/day and rituximab. He had a poor response to therapy, despite a reduction in the HHV-8 viral load, with clinical deterioration, transfusion-dependent anaemia and progression to multi-organ dysfunction leading to death three weeks after starting treatment. Our patient had a fulminant course of MCD despite treatment with rituximab. Further studies are needed to validate the different treatment modalities and to better understand the prognosis of this disease.

Human herpesvirus 8-associated multicentric Castleman disease in a patient with advanced HIV infection: A case report

RATIONAL

Multicentric Castleman disease (MCD) is a nonclonal lymphoproliferative disorder that is rarely reported from Southeast Asian countries. Here, we report a case of human herpesvirus 8 (HHV-8)-associated MCD in a patient with advanced human immunodeficiency virus (HIV) infection who presented with prolonged intermittent fever, urticarial rash, hepatosplenomegaly, and generalized lymphadenopathy.

PATIENT CONCERNS

A 34-year-old man with advanced HIV infection who was in good compliance with his antiretroviral treatment regimen presented with intermittent fever, weight loss, marked hepatosplenomegaly, and generalized lymphadenopathy. Recurrent symptoms of high-grade fever, abdominal discomfort, pancytopenia, and high C-reactive protein level occurred for 16 months.

DIAGNOSES

Histopathological findings of left inguinal lymph node revealed diffuse effacement of lymph node architecture with coexpression of HHV-8 latency-associated nuclear antigen 1 from immunohistochemical staining. The HHV-8 viral load was 335,391 copies/mL.

INTERVENTIONS

The patient was treated initially with one dose of intravenous rituximab (375 mg/m2) followed by subcutaneous rituximab (1400 mg) weekly for 5 weeks.

OUTCOMES

The patient's recurrent systemic symptoms subsided dramatically, and he has now been in remission for almost two years.

LESSONS

HHV8-associated MCD remains a diagnostic challenge in advanced HIV disease and should be suspected in those with recurrent flares of systemic inflammatory symptoms. Lymph node histopathology is essential for diagnosis and for excluding clonal malignancy. HHV-8 viral load is also useful for diagnosis and for monitoring disease activity.

Castleman disease

Castleman disease (CD), a heterogeneous group of disorders that share morphological features, is divided into unicentric CD and multicentric CD (MCD) according to the clinical presentation and disease course. Unicentric CD involves a solitary enlarged lymph node and mild symptoms and excision surgery is often curative. MCD includes a form associated with Kaposi sarcoma herpesvirus (KSHV) (also known as human herpesvirus 8) and a KSHV-negative idiopathic form (iMCD). iMCD can present in association with severe syndromes such as TAFRO (thrombocytopenia, ascites, fever, reticulin fibrosis and organomegaly) or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes). KSHV-MCD often occurs in the setting of HIV infection or another cause of immune deficiency. The interplay between KSHV and HIV elevates the risk for the development of KSHV-induced disorders, including KSHV-MCD, KSHV-lymphoproliferation, KSHV inflammatory cytokine syndrome, primary effusion lymphoma and Kaposi sarcoma. A CD diagnosis requires a multidimensional approach, including clinical presentation and imaging, pathological features, and molecular virology. B cell-directed monoclonal antibody therapy is the standard of care in KSHV-MCD, and anti-IL-6 therapy is the recommended first-line therapy and only treatment of iMCD approved by the US FDA and EMA.

KSHV/HHV8-Associated Lymphoproliferative Disorders: Lessons Learnt from People Living with HIV

In 1992, Kaposi sarcoma herpesvirus (KSHV/HHV8) was discovered and identified as the causative agent for Kaposi sarcoma. Subsequently, the presence of this virus has been detected in a number of lymphoproliferative disorders in people living with HIV (PLWH), including: KSHV-associated multicentric Castleman disease, primary effusion lymphoma, KSHV-positive diffuse large B-cell lymphoma, and germinotropic lymphoproliferative disorder. Each of these rare entities has subsequently been diagnosed in HIV-negative individuals. The recognition of some of these KSHV/HHV8-associated lymphoproliferative disorders has led to their inclusion in the WHO classification of lymphomas in 2008 and the revision of 2016; however, further revision is under way to update the classification. The relatively recent recognition of these lymphoproliferative disorders and their low incidence, particularly in the HIV-negative population, means that there is little published evidence and consensus on their clinical features and management. The publication of a new WHO classification of lymphomas should yield diagnostic clarity, providing an impetus for retrospective case series and prospective clinical trials in these KSHV/HHV8-associated lymphoproliferative disorders.

Kaposi's sarcoma-associated herpesvirus: the role of lytic replication in targeted therapy

PURPOSE OF REVIEW

To discuss the role of Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in viral-associated diseases and assess the progress on targeting KSHV lytic replication as a strategy to prevent KSHV-related malignancies.

RECENT FINDINGS

New inhibitors of viral lytic replication are being developed as well as novel modalities are being investigated to target cellular processes that the virus hijacks during its life cycle. Research has also focused on reactivating viral lytic replication in latently infected tumour cells (lytic induction therapy) to promote death of tumour cells.

SUMMARY

KSHV is linked to three malignancies: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Despite significant progress in understanding KSHV pathobiology, no therapeutic guidelines for the management of KSHV-related diseases exist, and current treatments are suboptimal and associated with toxicity. Antiherpesvirus drugs have shown inconsistent results in KSHV-associated malignancies that harbour the virus in a latent state. However, lytic replication plays a crucial role in the process of tumorigenesis. Therefore, not only antiviral agents directed against the virus replicative cycle but also agents that target cellular processes that are activated by the virus are being investigated. Antivirals may also be used in combination with inducers of the viral lytic stage.

Practical Management of Castleman's Disease

Castleman's disease (CD) is a rare lymphoproliferative disorder that is most commonly present in multicentric (MCD) form in association with HIV infection. Interleukin-6 (IL-6) and human herpesvirus-8 (HHV-8) play major roles in MCD pathogenesis. Important treatment options have recently become available, particularly with the introduction of IL-6 and IL-6 receptor inhibitors for the treatment of HIV-negative patients with MCD. Though advances in therapy may improve outcomes in some patients, the prognosis remains guarded, and a stratified approach to the management of MCD is needed.

Diagnosis and management of Castleman disease

BACKGROUND

Castleman disease is an uncommon lymphoproliferative disorder characterized as either unicentric or multicentric. Unicentric Castleman disease (UCD) is localized and carries an excellent prognosis, whereas multicentric Castleman disease (MCD) is a systemic disease occurring most commonly in the setting of HIV infection and is associated with human herpesvirus 8. MCD has been associated with considerable morbidity and mortality, and the therapeutic landscape for its management continues to evolve.

METHODS

The available medical literature on UCD and MCD was reviewed. The clinical presentation and pathological diagnosis of Castleman disease was reviewed, along with associated disorders such as certain malignancies and autoimmune complications.

RESULTS

Surgical resection remains the standard therapy for UCD, while systemic therapies are required for the management of MCD. Rituximab monotherapy is the mainstay of therapy; however, novel therapies targeting interleukin 6 may represent a treatment option in the near future. Antiviral strategies as well as single-agent and combination chemotherapy with glucocorticoids are established systemic therapies. The management of Castleman disease also requires careful attention to potential concomitant infections, malignancies, and associated syndromes.

CONCLUSIONS

UCD and MCD constitute uncommon but well-defined clinicopathologic entities. Although UCD is typically well controlled with local therapy, MCD continues to pose formidable challenges in management. We address historical chemotherapy-based approaches to this disease as well as recently developed targeted therapies, including rituximab and siltuximab, that have improved the outcome for newly diagnosed patients. Ongoing research into the management of MCD is needed.

Human immunodeficiency virus-associated multicentric Castleman disease refractory to antiretroviral therapy: clinical features, treatment and outcome

Human immunodeficiency virus (HIV)-associated multicentric Castleman disease (MCD) is a lymphoproliferation associated with human herpes virus-8 (HHV-8). Optimal treatment in patients not responding to antiretroviral therapy (ART) is undefined. We report 12 patients with ART refractory HIV-MCD. Patients with HIV-MCD were identified and baseline characteristics, treatment and outcome considered. Median CD4 count at HIV-MCD diagnosis was 295 (60-950) cells/mL. All patients had waxing and waning systemic symptoms, lymphadenopathy and/or splenomegaly, with non-Hodgkin lymphoma (NHL) in three. Treatment included: anti-HHV-8 therapy, n = 8; alone, n = 4; with systemic chemotherapy (CT) ± immunotherapy (IT), n = 4; CT ± IT only, n = 2. Initial median HHV-8 viral load (VL) was 7 × 10(4) copies/mL and at follow-up < 40 in 6/7 survivors; and 403-7.2 × 10(6) in 4/5 who died. One patient developed NHL despite an HHV-8 VL < 40. HIV-MCD is challenging to treat. Suppression of plasma HHV-8 VL did not prevent development of NHL. Anti-HHV-8 therapy should probably be considered adjunctive to cytotoxic therapies.

Successful treatment of iatrogenic multicentric Castleman's disease arising due to recrudescence of HHV-8 in a liver transplant patient

We describe the case of a 59-year-old HIV-negative male who developed multicentric Castleman's disease (MCD) 1 year postliver transplantation due to recrudescence of a pretransplant human herpesvirus-8 (HHV-8) infection. He presented with fevers, dry cough, weight loss and drenching night sweats. Routine investigations were all unremarkable. Computerized axial tomography (CT) scans showed splenomegaly and intra-abdominal lymphadenopathy, confirmed by positron emission tomography. Cervical lymph node biopsies were consistent with MCD. The presence of HHV-8 was confirmed on immunohistochemistry. Peripheral blood HHV-8 quantitative polymerase chain reaction (qPCR) monitoring showed a threefold decrease in viremia in the first week of treatment with ganciclovir but had little impact on clinical symptoms. Reducing immunosuppression and switching to rituximab resolved clinical symptoms and produced a negative HHV-8 qPCR result. Retrospective molecular testing of sera collected pre- and immediately posttransplantation confirmed preexisting HHV-8 in the host. This is the first reported case of an HIV-negative postliver transplant patient developing MCD that manifested as posttransplant lymphoproliferative disorder due to recrudescence of HHV-8. We propose (1) the introduction of the term iatrogenic Castleman's disease (CD) for this and similar cases, (2) rituximab should be considered as a treatment option for CD and (3) consideration be given to a change to the World Health Organization classification of CD to incorporate such cases.

Castleman disease

Castleman and Towne described a disease presenting as a mediastinal mass resembling thymoma. It is also known as "giant lymph node hyperplasia", "lymph node hamartoma", "angiofollicular mediastinal lymph node hyperplasia", and "angiomatous lymphoid hyperplasia". The pathogenesis is unknown, but the bulk of evidence points toward faulty immune regulation, resulting in excessive B-lymphocyte and plasma-cell proliferation in lymphatic tissue. In addition to the mediastinal presentation, extrathoracic involvement in the neck, axilla, mesentery, pelvis, pancreas, adrenal gland, and retroperitoneum also have been described. There are 2 major pathologic variations of Castleman disease: (1) hyaline-vascular variant, the most frequent, characterized by small hyaline-vascular follicles and capillary proliferation; and (2) the plasma-cell variant, in which large lymphoid follicles are separated by sheets of plasma cells. The hyaline-vascular cases usually are largely asymptomatic, whereas the less common plasma-cell variant may present with fever, anemia, weight loss, and night sweats, along with polyclonal hypergamma-globulinemia. Castleman disease is a rare lymphoproliferative disorders. Few cases have been described world widely. In this article we reviewed the classification, pathogenesis, pathology, radiological features and up to date treatment with special emphasis on the role of viral stimulation, recent therapeutic modalities and the HIV-associated disease.

Detection of human herpesvirus 8 by quantitative polymerase chain reaction: development and standardisation of methods

Background

Human herpesvirus 8 (HHV-8), the aetiological agent of Kaposi’s sarcoma (KS), multicentric Castleman’s disease (MCD), and primary effusion lymphoma (PEL) is rare in Australia, but endemic in Sub-Saharan Africa, parts of South-east Asia and Oceania. While the treatment of external KS lesions can be monitored by clinical observation, the internal lesions of KS, MCD and PEL require extensive and expensive internal imaging, or autopsy. In patients with MCD and PEL, if HHV-8 viraemia is not reduced quickly, ~50% die within 24 months. HHV-8 qPCR is a valuable tool for monitoring HHV-8 viraemia, but is not available in many parts of the world, including those with high prevalence of KS and HHV-8.

Methods

A new molecular facility with stringent three-phase workflow was established, adhering to NPAAC and CLSI guidelines. Three fully validated quantitative assays were developed: two for detection and quantification of HHV-8; one for GAPDH, necessary for normalisation of viral loads in tissue and peripheral blood.

Results

The HHV-8 ORF73 and ORF26 qPCR assays were 100% specific. All qPCR assays, displayed a broad dynamic range (10² to 10¹⁰ copies/μL TE Buffer) with a limit of detection of 4.85x10³, 5.61x10², and 2.59x10² copies/μL TE Buffer and a limit of quantification of 4.85x10³, 3.01x10², and 1.38x10² copies/μL TE Buffer for HHV-8 ORF73, HHV-8 ORF26, and GAPDH respectively.

The assays were tested on a panel of 35 KS biopsies from Queensland. All were HHV-8 qPCR positive with average viral load of 2.96x10⁵ HHV-8 copies/μL DNA extract (range: 4.37x10³ to 1.47x10⁶ copies/μL DNA extract): When normalised these equate to an average viral load of 2.44x10⁴ HHV-8 copies/10³ cells (range: 2.20x10² to 7.38x10⁵ HHV-8 copies/10³ cells).

Conclusions

These are the first fully optimised, validated and MIQE compliant HHV-8 qPCR assays established in Australia. They worked well for qualitative detection of HHV-8 in archival tissue, and are well-suited for quantitative detection in whole blood. They are now available for research, for clinical diagnosis of HHV-8 infection, and for monitoring treatment efficacy.

Diffusion-weighted whole-body imaging with background body signal suppression in Castleman disease

Castleman's disease (CD) is a rare lymphoproliferative disease characterized by angiofollicular lymph node hyperplasia. The case of a 74-year-old man with multicentric CD of the plasma cell type is described. The imaging findings on diffusion-weighted whole-body imaging with background body signal suppression at diagnosis and after treatment are reported.

HIV-associated multicentric Castleman disease

PURPOSE OF REVIEW

HIV-associated multicentric Castleman disease (HIV MCD) is a rare lymphoproliferative disorder, the incidence of which appears to be increasing in the highly active antiretroviral therapy era. Current knowledge of the disease is limited and this review will discuss what is known about the pathophysiology, diagnosis, management, and prognosis of HIV MCD.

RECENT FINDINGS

HIV MCD has been shown to be associated with infection with human herpesvirus-8. Vascular endothelial growth factor and the cytokine interleukin-6 (IL-6) are also thought to play a role in the pathogenesis of MCD. Currently, rituximab is often used alone or in combination with chemotherapy for treatment of MCD. Novel monoclonal antibodies targeting IL-6 and the IL-6 receptor are also being studied for the management of this disease.

SUMMARY

Because HIV MCD is an uncommon diagnosis, comprehensive clinical studies have not been done, and understanding of the disease is incomplete. Further studies are needed to make definitive conclusions regarding optimal treatment of HIV MCD.

Improved outcome with rituximab in patients with HIV-associated multicentric Castleman disease

Although HIV-associated multicentric Castleman disease (HIV-MCD) is not classified as an AIDS-defining illness, mortality is high and progression to lymphoma occurs frequently. At present, there is no widely accepted recommendation for the treatment of HIV-MCD. In this retrospective (1998-2010), multicentric analysis of 52 histologically proven cases, outcome was analyzed with respect to the use of different MCD therapies and potential prognostic factors. After a mean follow-up of 2.26 years, 19 of 52 patients died. Median estimated overall survival (OS) was 6.2 years. Potential risk factors, such as older age, previous AIDS, or lower CD4 T cells had no impact on OS. Treatment was heterogeneous, consisting of cytostatic and/or antiviral agents, rituximab, or combinations of these modalities. There were marked differences in the outcome when patients were grouped according to MCD treatment. Patients receiving rituximab-based regimens had higher complete remission rates than patients receiving chemotherapy only. The mean estimated OS in patients receiving rituximab alone or in combination with cytostatic agents was not reached, compared with 5.1 years (P = .03). Clinical outcome and overall survival of HIV-MCD have markedly improved with rituximab-based therapies, considering rituximab-based therapies (with or without cytostatic agents) to be among the preferred first-line options in patients with HIV-MCD.

How I treat HIV-associated multicentric Castleman disease

HIV-associated plasmablastic multicentric Castleman disease is an increasingly frequent diagnosis. Kaposi sarcoma herpesvirus is found in the monotypic polyclonal plasmablasts that characterize this disease. Unlike Kaposi sarcoma, the incidence does not correlate with CD4 cell count or use of highly active antiretroviral therapy. It is a relapsing and remitting illness, and diagnostic criteria are emerging that define disease activity based on the presence of a fever and raised C-reactive protein coupled with a list of clinical features. Treatment protocols increasingly stratify therapy according to performance status and organ involvement. I advocate rituximab monotherapy for good performance status patients without organ involvement and rituximab with chemotherapy for more aggressive disease. The success of antiherpesvirus agents in controlling active disease is limited, but valganciclovir may have a role as maintenance therapy in the future.

Multicentric hyaline-vascular type Castleman disease presenting as an epidural mass causing paraplegia: a case report

A 30-year-old woman presented with a 1-year history of cervical lymph node enlargement and paraparesis of 2 weeks' duration. Magnetic resonance imaging revealed an epidural mass extending from the second to fifth thoracic levels causing compressive myelopathy. The cervical lymph node biopsy revealed hyaline vascular multicentric Castleman disease. She was given dexamethasone and radiation therapy to the involved spine followed by 8 cycles of CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone) chemotherapy. The patient achieved complete remission and is disease free 24 months after treatment. The case is being reported in view of its rarity and achievement of complete remission with chemotherapy and radiation therapy.

HIV-associated multicentric Castleman's disease

Multicentric Castleman's disease (MCD), a relatively rare lymphoproliferative disorder that presents with heterogenous symptoms including fevers, anemia, and multifocal lymphadenopathy, is today most commonly observed in individuals infected with human immunodeficiency virus type-1 (HIV). In such individuals, a lymph node biopsy typically identifies cells that stain for Kaposi's sarcoma-associated herpesvirus proteins, and most HIV-associated MCD features can be attributed to the presence of this gamma-herpesvirus. Surgery and antiviral therapies including highly active antiretroviral therapy, interferon-alpha, foscarnet, ganciclovir, and antibodies to interleukin-6 have proved largely ineffective, and chemotherapy in HIV positive individuals is complicated by limited efficacy and pronounced toxicity. While no randomized trials have been performed, more recently the use of the anti-CD20 monoclonal antibody rituximab in large single center cohorts has been associated with prolonged remissions, radiologic responses, as well as hematologic and serum chemistry normalization of the inflammatory picture observed, at the expense of B cell depletion and flare of Kaposi's sarcoma. MCD represents a model of disease at the interplay between tumor biology, infection, and immunology.

Retinoic Acid Analogues Inhibit Human Herpesvirus 8 Replication

Background

Retinoids have a pronounced antiviral effect against several viruses. In this study we aimed to investigate the effect of retinoids on human herpesvirus 8 (HHV-8).

Methods

A panel of retinoic acid compounds were tested for their antiviral activity against HHV-8 in human umbilical vascular endothelial cells (HUVECs) and in a human epithelial cell line. The presence, transcription and antigen expression of HHV-8 in infected cells – in the presence or absence of retinoic acid compounds – were evaluated by PCR, reverse transcriptase PCR and immunofluorescence assays; HHV-8 viral load was determined by real-time quantitative PCR. Angiogenesis induced by HHV-8 was also assessed using Cultrex® basement membrane extract.

Results

The compounds tested specifically inhibited viral promoters, during the early and late phases of infection in both cell systems tested, and resulted in up to 100fold reduction of viral titre and release of progeny virus. The inhibition of viral replication induced by retinoids in endothelial cells, the primary target of HHV-8-driven transformation in Kaposi's Sarcoma, prevented endothelial cells from developing spindle morphology and in vitro tube formation, characteristic changes associated with HHV-8 infection and transformation.

Conclusions

We show that retinoids inhibit HHV-8 replication and identify new retinoid compounds with a strong antiviral effect. Selective retinoids, particularly those with retinoic acid receptor agonist activity, may be good candidates for the development of antiviral drugs.

AIDS malignancies

Among individuals with HIV-infection, coinfection with oncogenic viruses including EBV, HHV-8, and HPV cause significant cancer-related morbidity and mortality. It is clear that these viruses interact with HIV in unique ways that predispose HIV-infected individuals to malignant diseases. In general, treatment directed specifically against these viruses does not appear to change the natural history of the malignant disease, and once the malignancy develops, if their health permits, HIV-infected patients should be treated using similar treatment protocols to HIV-negative patients. However, for the less frequent HIV-related malignancies, such as PEL, or MCD, optimal treatments are still emerging. For certain AIDS-defining malignancies, it is clear that the widespread access to HAART has significantly decreased the incidence, and improved outcomes. However, for other cancers, such as the HPV-related tumors, the role of HAART is much less clear. Further research into prevention and treatment of these oncogenic virally mediated AIDS-related malignancies is necessary.

[Castleman's disease]

CASE REPORT

A 25-year-old patient with fever, dysphagia, and reduced general condition was referred to our department by his dentist after 1 week of antibiotic therapy. He presented with a painful palpable mass in the right lower jaw that had developed 2 weeks before. The orthopantomogram showed a caries and periapical lesion at the right lower wisdom tooth. During extraction of the tooth and putative intra- and extraoral abscess incision, no pus could be drained and the mass persisted. CT scans then revealed lobulated soft tissue masses on both sides of the neck with the main focus on the right side. In an additional operation with excision of the mass, Castleman's disease of the hyaline vascular type was diagnosed.

HISTOPATHOLOGIC FINDINGS

Staging could not detect further pathological findings and the patient's postoperative general condition improved continuously. The histological features of the hayline vascular type of Castleman's disease were characterized by multiple germinal centers surrounded by circumferentially arranged layers of small lymphocytes interconnected by a prominent vascular stroma with occasional plasma cells ("onion skin").

CONCLUSION

Castleman's disease is a rare and yet poorly understood disease, characterized by inhomogeneous growth of lymphoid tissue. Mostly benign it remains a diagnostic challenge before histological investigation. In unclear submandibular swellings and neck lumps assumed to be an abscess, this rare differential diagnosis must be considered. Facing recurrence and potential for malignancy, follow-up of the patients over several years is necessary.

The aetiology and management of Castleman disease at 50 years: translating pathophysiology to patient care

Fifty years ago, Dr Benjamin Castleman first described the unusual lymphoproliferative disorder that now bears his name. Over the subsequent decades, astute clinical and pathologic observations coupled with clever molecular biologic research have increased our understanding of the aetiology of Castleman disease (CD). This article proposes three broad CD variants based on both distinctive histopathology and clinical behaviour. The pivotal roles of infection with human herpesvirus 8 and interleukin-6 production in the development of CD are emphasized. Finally, the natural history of CD and the myriad of therapeutic options are reviewed in the context of a unified model of CD pathophysiology, and continued areas of uncertainty are discussed.

Fifty years of multicentric Castleman's disease

Benjamin Castleman first described multicentric Castleman's disease (MCD) in a series of cases in 1954. Interest in MCD has grown in recent years following an association with human immunodeficiency virus (HIV) infection. Castleman's disease is separated into localized disease and MCD. The latter is characterized by polylymphadenopathy and multiorgan involvement. Histologically, Castleman's disease is divided into the hyalinized vascular form and a plasma cell variant, the former being more common in localized disease and the latter more common in MCD. MCD is associated with Kaposi's sarcoma herpesvirus (KSHV) infection, which is alternatively termed human herpesvirus 8 (HHV8). This virus encodes a homologue of interleukin 6 (vIL 6), which may mediate some systemic features of MCD. The diagnosis of Castleman's disease is established by biopsy and treatment is often based on published case reports only, as there are no randomized trials of therapy. Surgery has less of a role in MCD than in localized disease, but debulking by splenectomy may be useful to alleviate haematological sequelae. Systemic treatments for MCD have included chemotherapy, anti-herpesvirus treatments to reduce the KSHV viral load, highly active antiretroviral therapy (HAART) to reduce HIV viraemia and latterly monoclonal antibodies against both IL 6 and CD20. The introduction of HAART has altered the natural history of HIV infection; however, its impact on MCD is difficult to ascertain. Optimization and consensus in treatment of these patients remains a target for the future.

Therapeutic options for human herpesvirus-8/Kaposi's sarcoma-associated herpesvirus-related disorders

Human herpesvirus-8/Kaposi's sarcoma-associated herpesvirus infection is associated with three proliferative disorders in immunocompromised patients - Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. These disorders often develop in patients with advanced AIDS who present a number of therapeutic challenges, underscoring the importance of continuing efforts dedicated to basic and clinical research in this field. In the era of highly active antiretroviral therapy, the incidence of AIDS and Kaposi's sarcoma has considerably decreased, presumably due to enhanced anti-Kaposi's sarcoma-associated herpesvirus immune responses, whereas the situation with primary effusion lymphoma and multicentric Castleman's disease is more complex. Based on advances in the understanding of Kaposi's sarcoma-associated herpesvirus-related disorders and availability of antiretroviral agents, current and future therapeutic approaches will be discussed.