Dissolution of the lymphoid follicle is a feature of the HHV8+ variant of plasma cell Castleman's disease

From the archives of MD Anderson Cancer Center Castleman disease involving the thymus gland: Case report and literature review

Castleman disease is a nodal based disease and very rarely involves the thymus gland. We report a 52-year-old man who was found incidentally to have a single thymic mass by computerized tomography scan. Thymectomy was performed, and the gross specimen showed a well-circumscribed, multi-loculated cystic mass. Histologic examination showed thymus involved by Castleman disease, hyaline-vascular variant. The lesion was characterized by lymphoid follicles with wide mantle zones, variably lymphocyte-depleted germinal centers with sclerotic radial blood vessels, and prominent interfollicular/stromal changes including numerous endothelial venules with sclerotic walls and hyaline sclerosis, scattered and frequent dysplastic follicular dendritic cells and foci of dystrophic calcification. Immunohistochemical analysis showed that the follicle mantle zones were composed of numerous B-cells positive for CD20, PAX5, and IgD. Antibodies specific for CD21 and CD23 highlighted prominent follicular dendritic cell networks within follicles. There was no evidence of human herpes virus 8. We searched the literature and could identify only 10 additional cases of thymic CD. Previously reported cases included 8 unicentric and 2 multicentric, classified pathologically as plasma cell variant (n = 4), hyaline vascular variant (n = 3), and mixed (n = 3). Thymectomy, as was done in the currently reported case, most often leads to the diagnosis of Castleman disease and was a mainstay of treatment in other reported cases.

Clinical and histopathology characteristics of Castleman disease: a multicenter study of 51 Brazilian patients

Castleman's disease (CD) is a rare and heterogeneous lymphoproliferative disorder, with limited available clinical information in Brazil. A retrospective study was carried out through information contained in the medical records of 51 patients, between July 1999 and June 2020. Seven patients were excluded, and 44 were analyzed in total. The average age of unicentric CD (UCD) patients was 35 years old and of multicentric CD (MCD) patients was 49 years old (p = 0.013). Regarding gender, there was a predominance of females among patients with UCD (68.4%) and males in patients with MCD (57.9%) (p = 0.103). The most common site of involvement in UCD was the cervical region (36.8%). A total of 73.7% of patients with UCD and 68.4% of patients with MCD presented the histological form hialyne-vascular (HV) (p = 0.499). Most patients with laboratory abnormalities had MCD. A total of 78% of the patients were asymptomatic, with the majority of symptomatic patients with MCD (p = 0.042). Only two of the 27 patients evaluated for the presence of human immunodeficiency virus (HIV) had positive serology. HHV-8 was evaluated in 14 cases, being positive in two. Of the patients with UCD, 94.7% underwent excisional biopsy, against only 41.2% of patients with MCD (p = 0.01). The mean follow-up was 61 months. We observed similarities in the clinical profile between patients in our study and patients described in the literature, such as gender, mean age, B symptoms, visceromegaly, fluid accumulation, and treatment. Unlike the literature, the cervical region was the most affected site, besides the greater association of the HV histological subtype among patients with MCD.

[Castleman disease]

The term "Castleman disease" covers a variety of entities that have very different clinical, biological, pathological and physiopathological features. In this issue, we review the characteristics of the unicentric Castleman disease, of the HHV8 associated multicentric Castleman disease and the idiopathic multicentric Castleman disease associated or not with TAFRO syndrome ("thrombocytopenia, anasarca, fever, reticulin myelofibrosis and/or renal insufficiency, organomegaly"). We detail the differential diagnostics of these entities.

Follicular dendritic cell sarcoma

Follicular dendritic cells (FDC) are mesenchymal-derived dendritic cells located in B-follicles where they play a pivotal role in triggering and maintaining B-cell adaptive immune response. In 1986 Dr. Juan Rosai first reported a series of neoplasms showing features of FDC and defined it as Follicular Dendritic Cell Tumor, subsequently renamed as "sarcoma" (FDCS). In its seminal and subsequent articles Rosai and colleagues highlighted the heterogeneous microscopic appearance of FDCS and its immunohistochemical and ultrastructural features.

FDCS mostly occurs in extranodal sites (79.4% of cases) and lymph nodes (15.1%); in about 7%-10% of cases it is associated with hyaline-vascular Castleman disease. Given its significant growth pattern and cytological variability, FDCS can be confused with various neoplasms and even inflammatory processes. The diagnosis requires the use of a broad spectrum of FDC markers (e.g. CD21, CD23, CD35, clusterin, CXCL13, podoplanin), particularly considering that tumor antigen-loss is frequent. The inflammatory-pseudotumor-like (IPT-like) variant of FDCS, in addition to its peculiar histopathological and clinical features, is characterized by positivity of tumor cells for Epstein-Barr virus, representing a diagnostic requisite.

No distinctive genetic and molecular anomalies have been identified in FDCS. It often carries an aberrant clonal karyotype and chromosomal structural alterations, frequently involving onco-suppressor genes. Direct or next generation sequencing showed alterations on genes belonging to the NF-κB regulatory pathway and cell-cycle regulators. In contrast to hematopoietic-derived histiocytic and dendritic cells tumors, FDCS typically lacks mutations in genes related to the MAPK pathway.

FDCS recurs locally in 28% and metastasizes in 27% of cases. Extent of the disease, surgical resectability and histopathological features are significantly associated with the outcome. IPT-like FDCS behaves as an indolent tumor, even if it often recurs locally over years.

Complete surgical excision is the gold standard of treatment. Data on targeted therapies (e.g.: tyrosine kinase inhibitors) or immune checkpoint inhibitors are very limited and responses are variable. A better understanding of the molecular drivers of this tumor may lead to potential new therapeutic strategies.

Overview of Castleman disease

Castleman disease (CD) describes a group of at least 4 disorders that share a spectrum of characteristic histopathological features but have a wide range of etiologies, presentations, treatments, and outcomes. CD includes unicentric CD (UCD) and multicentric CD (MCD), the latter of which is divided into idiopathic MCD (iMCD), human herpes virus-8 (HHV8)-associated MCD (HHV8-MCD), and polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS)-associated MCD (POEMS-MCD). iMCD can be further subclassified into iMCD-thrombocytopenia, ascites, reticulin fibrosis, renal dysfunction, organomegaly (iMCD-TAFRO) or iMCD-not otherwise specified (iMCD-NOS). Advances in diagnosis, classification, pathogenesis, and therapy are substantial since the original description of UCD by Benjamin Castleman in 1954. The advent of effective retroviral therapy and use of rituximab in HHV8-MCD have improved outcomes in HHV8-MCD. Anti-interleukin-6-directed therapies are highly effective in many iMCD patients, but additional therapies are required for refractory cases. Much of the recent progress has been coordinated by the Castleman Disease Collaborative Network (CDCN), and further progress will be made by continued engagement of physicians, scientists, and patients. Progress can also be facilitated by encouraging patients to self-enroll in the CDCN's ACCELERATE natural history registry (#NCT02817997; www.CDCN.org/ACCELERATE).

Castleman Disease

Castleman disease (CD) is divided clinically into unicentric or multicentric type. Pathologically, CD is divided into hyaline-vascular and plasma cell variants. Unicentric CD is most common, about 75% of these cases are hyaline-vascular variant, and surgical excision is often curative. In contrast, there are a number of types of multicentric CD including HHV8-associated, idiopathic, and a subset of cases that arise in association with POEMS syndrome. Therapy is required for most patients with multicentric CD, but there is no consensus approach currently. As is evidence, the designation Castleman disease encompasses a heterogeneous group of diseases of varied pathogenesis and which require different therapies.

The Peripheral Neuropathies of POEMS Syndrome and Castleman Disease

Polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS) syndrome is a rare paraneoplastic disorder. The polyneuropathy can be the presenting symptom and is typically a painful, motor-predominant polyradiculoneuropathy often mimicking chronic inflammatory demyelinating polyradiculoneuropathy. The presence of a lambda monoclonal protein, elevated vascular endothelial growth factor, systemic features, and treatment resistance are clues to the diagnosis. Castleman disease (CD) is seen in a subset of these patients, and when present the neuropathy is similar but less severe. In contrast, in those patients with purely CD, the neuropathy is often a mild, painless distal sensory neuropathy.

Molecular approaches towards characterization, monitoring and targeting of viral-associated hematological malignancies

Viral-associated malignancies usually arise in the setting of altered immunity or with declines in immune function associated with aging. The main culprits are the lymphotropic herpesvirus, including Epstein-Barr virus (EBV) and human herpesvirus-8, which are the focus of this review. Chronic persistent infection and viral reactivation are the main risk factors for development of herpesvirus-associated malignancies and have provided the rationale for intensive monitoring of viral loads in some clinical contexts. Quantitative detection of EBV levels in the post-transplant period and following treatment of EBV-associated malignancies now have a proven role in outcome prediction. Both T-cell immunotherapy and humoral immunotherapies directed against latent viral antigens represent promising interventional approaches to treatment of viral-associated malignancies.

The clinical spectrum of Castleman's disease

Castleman's disease (CD) is a rare, poorly understood lymphoproliferative disease. The spectrum of symptoms and course of disease are broad, but there is no large study describing the natural history of this disease. Basic clinic and laboratory data from the records of 113 patients with CD evaluated at the Mayo Clinic and University of Nebraska were abstracted. The impact of these variables on overall survival (OS) from time of diagnosis was evaluated. Sixty patients had multicentric disease. Of the patients with multicentric CD, 32% had criteria sufficient for a diagnosis of POEMS syndrome. For all patients, 2, 5, and 10-year OS was 92%, 76%, 59%, respectively. Most of the factors identified as risk factors for death on univariate analysis cosegregated with diagnostic criteria for POEMS syndrome, which supported the concept of four categories of CD, which are (along with their 5-year OS): (1) unicentric CD (91%); (2) multicentric CD associated with the osteosclerotic variant of POEMS syndrome (90%); (3); multicentric CD without POEMS syndrome (65%); and (4) multicentric CD with POEMS syndrome without osteosclerotic lesions (27%). We have demonstrated that CD represents a spectrum of disease that can be differentiated by simple prognostic factors that provide a framework for further study.

Castleman's disease in childhood: report of three cases and review of the literature

Castleman's disease (CD) is a rare, localized or generalized, lymphoproliferative disorder with a frequent mediastinal location, but possible in any lymph node or extra nodal site. It usually appears in young adults whilst it rarely occurs in childhood. There are only about 100 pediatric cases published, five of them in Italy. We report 3 cases of localized Castleman's disease, investigated in our Department in a 3 years period and reviewed the literature.

Three patients with both Hodgkin's lymphoma and Castleman's disease: Clinicopathologic correlations and lack of association with HHV-8

Background:

The relationship between Hodgkin's lymphoma (HL) and plasma cell-type Castleman's disease (PCD) has been well documented. There have been over 20 cases reported in the literature and nearly all of them were either diagnosed concurrently, or were initially diagnosed as PCD and upon review were found to have interfollicular HL. Human herpes virus type 8 (HHV-8) is present in about 40% of cases with PCD. It predisposes patients to a much higher risk of other malignancies, including Kaposi's sarcoma and non-Hodgkin's lymphoma. Cases linked to HHV-8 are associated with a different morphology than cases that are not linked to HHV-8. It has been proposed that patients with both HL and CD will have lymph nodes with HHV-8-negative morphology.

Materials and Methods:

We present a series of three cases in a retrospective study where patients had both HL and PCD. Surgical pathology reports, clinical histories, and H and E and various immunohistochemical stains on initial work-up were examined and subsequent immunohistochemical stains for HHV-8 were obtained from the Methodist Hospital.

Results:

Patient 1 was diagnosed with PCD and interfollicular HL in the same lymph node. Patient 2 was first diagnosed with classic HL and 2 years later returned with enlarged lymph nodes clinically suspected to be recurrent HL. Histology showed angiofollicular hyperplasia and interfollicular plasmacytosis without Reed-Sternberg cells and a diagnosis of PCD was rendered. Patient 3, a male in his third decade, was diagnosed with nodular sclerosing HL in the thymus, and concurrently PCD in the mediastinal lymph nodes. All three cases had architectural features consistent with an HHV-8-negative morphology. Immunohistochemical stains for HHV-8 were done retrospectively and were negative.

Conclusion:

All three of our patients with both HL and CD had HHV-8-negative lymph node morphology and absence of HHV-8 by immunohistochemistry. These patients, therefore, are not at an increased risk for the development of subsequent malignancies, when compared to HHV-8-positive patients. Included in our series is one unique case where the diagnosis of HL preceded CD by 2 years.

Post-liver transplantation multicentric Castleman disease treated with valganciclovir and weaning of immunosuppression

Multicentric Castleman disease is a lymphoproliferative disorder which when seen in the setting of HIV/AIDS is often associated with human herpes virus 8 (HHV-8) infection. We describe the case of a HIV-negative man who developed HHV-8-associated multicentric Castleman disease 11 years after liver transplantation. The patient presented with fevers and weight loss. Physical examination revealed enlarged cervical, axillary and inguinal lymph nodes. Widespread lymphadenopathy was confirmed on computed tomography (CT) scanning. Histology of an enlarged lymph node showed a polymorphous infiltrate with mature plasma cells, plasmacytoid lymphocytes and occasional blasts within the cortex and paracortex. The diagnosis of Castleman disease was confirmed by the finding of numerous HHV-8-immunopositive cells around the regressed lymph node follicles and the detection of HHV-8 on plasma PCR. Although the conventional treatment for this condition has been combination chemotherapy, in the post-transplant context it was decided to treat the patient with valganciclovir and cessation of immunosuppression. His symptoms resolved rapidly and repeat plasma PCR done 3 months after starting treatment was negative for HHV-8. A follow-up CT scan showed a dramatic reduction in the size and amount of lymphadenopathy. After 15 months of treatment, he remains well with no evidence of graft dysfunction or rejection.

Hyaline-vascular castleman disease: a rare cause of solitary subcutaneous soft tissue mass

Castleman disease (CD) is a rare lymphoproliferative disorder that primarily affects mediastinal, retroperitoneal, and cervical lymph nodes. Clinically, these lesions occur as a localized (unicentric) or less frequently as a systemic (multicentric) disease. Two main distinct histologic variants are recognized, the more common hyaline-vascular (HV) type and the plasma cell (PC) type. Extranodal Castleman disease, HV type (HVCD) is even less common. We describe a case of subcutaneous HVCD in a 57-year-old woman with a palpable chest mass and without systemic symptoms. Although the histologic findings are similar to those of HVCD in lymph nodes and other sites, a plethora of differential diagnosis is raised particularly with the more commonly occurring lymphoproliferative lesions in this location. This is one of the few bona fide cases of HVCD in subcutaneous location published to date. A review of the literature with an emphasis on pathogenesis of the disease subtypes is presented.

Kaposi sarcoma herpes virus-associated hemophagocytic syndrome complicated by multicentric castleman disease and kaposi sarcoma in a HIV-negative immunocompetent patient: an autopsy case

Kaposi sarcoma herpes virus (KSHV), also known as human herpesvirus-8, plays an important role in the pathogenesis of Kaposi sarcoma (KS), multicentric Castleman disease (MCD) of the plasma cell type, and primary effusion lymphoma. KSHV is rarely associated with the hemophagocytic syndrome (HPS), but when it does occur, it most occurs in immunocompromised patients. We report herein an unusual case of KSHV-associated HPS in an immunocompetent patient. A previously healthy 62-yr-old male was referred for evaluation of leukocytopenia and multiple lymphadenopathies. After a lymph node biopsy, he was diagnosed with MCD of the plasma cell type. KSHV DNA was detected in the lymph node tissue by polymerase chain reaction. Following a short-term response of the leukocytopenia to prednisolone, mental change, left side weakness, fever, thrombocytopenia, hemolytic anemia, and renal failure developed. Despite intravenous immunoglobulin therapy and plasmapheresis, he expired. The lymph nodes were infiltrated by hemophagocytic histiocytes in the sinuses. Pulmonary nodules and gastric erosions were shown to be KS. KSHV DNA was detected in the stomach, lung, and liver. This is the first case of multiple KSHV associated diseases including MCD and KS with KSHV-associated hemophagocytic syndrome in an HIV-negative, non-transplant, immunocompetent patient.

Castleman disease: an update on classification and the spectrum of associated lesions

Since its initial description, researchers have expanded the spectrum of Castleman disease to include not only the classic and well-recognized hyaline-vascular type, but also the plasma cell type and multicentric types of broader histologic range, including human herpes virus-8-associated Castleman disease. These less common subtypes of Castleman disease are less familiar, and may be under-recognized. Also of practical importance, current authors are restructuring the classification of multicentric Castleman disease to accommodate the emerging pathogenic role of human herpes virus-8 and its association with the recently described plasmablastic variant. In addition to an increased risk of lymphoma, patients with Castleman disease also are at increased risk for other related neoplasms, including Kaposi sarcoma and follicular dendritic cell tumors, which are of prognostic and therapeutic relevance. This review focuses on the histologic diagnosis of Castleman disease, current and emerging concepts in its pathogenesis and classification, and associated histopathologic entities.

HIV-associated lymphomas and gamma-herpesviruses

Among the most common HIV-associated lymphomas are Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) with immunoblastic-plasmacytoid differentiation (also involving the central nervous system). Lymphomas occurring specifically in HIV-positive patients include primary effusion lymphoma (PEL) and its solid variants, plasmablastic lymphoma of the oral cavity type and large B-cell lymphoma arising in Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease. These lymphomas together with BL and DLBCL with immunoblastic-plasmacytoid differentiation frequently carry EBV infection and display a phenotype related to plasma cells. EBV infection occurs at different rates in different lymphoma types, whereas KSHV is specifically associated with PEL, which usually occurs in the setting of profound immunosuppression. The current knowledge about HIV-associated lymphomas can be summarized in the following key points: (1) lymphomas specifically occurring in patients with HIV infection are closely linked to other viral diseases; (2) AIDS lymphomas fall in a spectrum of B-cell differentiation where those associated with EBV or KSHV commonly exhibit plasmablastic differentiation; and (3) prognosis for patients with lymphomas and concomitant HIV infection could be improved using better combined chemotherapy protocols incorporating anticancer treatments and antiretroviral drugs.

Plasmablastic microlymphoma occurring in human herpesvirus 8 (HHV-8)-positive multicentric Castleman's disease and featuring a follicular growth pattern

Plasmablastic microlymphoma (PML) is defined as the accumulation of monotypic but polyclonal plasmablasts in lymphoid tissues involved in human herpes virus 8 (HHV-8)-positive multicentric Castleman's disease (MCD). So far, the nature of this very rare condition remains poorly determined. In this study, we describe a human immunodeficiency virus (HIV)-seropositive patient who developed a PML in the setting of HHV-8-positive MCD. In contrast to the cases previously reported, most of the plasmablasts in our patient were localized within the germinal center (GC) of lymphoid follicles. These plasmablasts expressed the multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF4) protein as well as IgMlambda in a monotypic fashion. They did not show any immunoreactivity with antibodies directed against Pax-5, CD20, CD79a, CD10, CD30, CD23, CD138, epithelial membrane antigen (EMA) or BCL-6. These cells exhibited a high proliferation rate, expressed the HHV-8 latent nuclear antigen-1, and secreted the HHV-8 viral homologue of human interleukin-6. Polymerase chain reaction analysis did not demonstrate any clonal rearrangement of the genes coding for the heavy chain of the immunoglobulin. Moreover, no Epstein-Barr virus (EBV) RNA transcript could be found, using in situ hybridization. The present case illustrates that PML may arise within the GC of lymphoid follicles in the absence of EBV coinfection. In our opinion, PML occurring in MCD likely represents a variant of HHV-8-positive MCD in which lytic HHV-8 replication is particularly prominent, due to a local or systemic immune imbalance.

Molecular biology of KSHV in relation to AIDS-associated oncogenesis

KSHV has been established as the causative agent of KS, PEL, and MCD, malignancies occurring more frequently in AIDS patients. The aggressive nature of KSHV in the context of HIV infection suggests that interactions between the two viruses enhance pathogenesis. KSHV latent infection and lytic reactivation are characterized by distinct gene expression profiles, and both latency and lytic reactivation seem to be required for malignant progression. As a sophisticated oncogenic virus, KSHV has evolved to possess a formidable repertoire of potent mechanisms that enable it to target and manipulate host cell pathways, leading to increased cell proliferation, increased cell survival, dysregulated angiogenesis, evasion of immunity, and malignant progression in the immunocompromised host. Worldwide, approximately 40.3 million people are currently living with HIV infection. Of these, a significant number are coinfected with KSHV. The complex interplay between the two viruses dramatically elevates the risk for development of KSHV-induced malignancies, KS, PEL, and MCD. Although HAART significantly reduces HIV viral load, the entire T-cell repertoire and immune function may not be completely restored. In fact, clinically significant immune deficiency is not necessary for the induction of KSHV-related malignancy. Because of variables such as lack of access to therapy noncompliance with prescribed treatment, failure to respond to treatment and the development of drug-resistant strains of HIV, KSHV-induced malignancies will continue to present as major health concerns.

The pleiotropic effects of Kaposi's sarcoma herpesvirus

Kaposi's sarcoma herpesvirus (KSHV), or human herpesvirus 8 (HHV8), is an essential factor in the pathogenesis of Kaposi's sarcoma (KS), multicentric Castleman's disease (MCD), and primary effusion lymphoma (PEL). Case reports suggest an occasional involvement in bone marrow hypoplasia and haemophagocytic syndrome, but other disease associations are unconfirmed or controversial. KSHV-associated disease is of particular importance in immunosuppressed individuals, in particular in patients with HIV infection and transplant recipients. KSHV establishes a latent infection in the majority of infected cells in KS, MCD, and PEL, but lytic replication occurs in a small fraction of infected cells. Viral proteins expressed during both the latent and the lytic phase of the viral life cycle contribute to the pathogenesis of KSHV-associated diseases.

Pulmonary parenchymal involvement of low-grade lymphoproliferative disorders

Lymphoid tissue is a normal component of the lung. The various lymphoproliferative diseases affect the lung parenchyma. The purpose of this article is to classify various lymphoproliferative diseases and to understand their computed tomography features of pulmonary involvement. The examples include follicular bronchiolitis, lymphocytic interstitial pneumonia, plasma cell granuloma, Castleman disease, lymphomatoid granulomatosis, and mucosa-associated lymphoid tissue lymphoma. Pathologic correlation is helpful for understanding imaging findings and their pathophysiology.

[Transitional type of Castleman's disease manifested as the POEMS syndrome]

BACKGROUND

Castleman's disease is an atypical lymphoproliferative disorder characterized by angiofollicular hyperplasia of lymph nodes. Histologically, it can be classified into a hyaline-vascular type, plasma-cell type, and transitional (mixed-cell) type, while clinically localized type has been classified as unicentric, or generalized (multicentric) form of the disease.

CASE REPORT

This paper presents a 21 year old male patient with multicentric Castleman's disease, a transitional (mixed-cell) type. The disease was manifested by fever, generalized enlargement of peripheral lymph nodes, breast glands enlargement, hyperemia of the face, and weakness of the lower extremities. We found mediastinal lymphadenopathy, pleural and pericardial effusions, sensorimotor peripheral neuropathy and polyclonal hypergammaglobulinemia. The simultaneous presence of these manifestations of the disease (sensomotor peripheral neuropathy, lymphadenopathy, effusions, endocrinopathy, polyclonal gammaglobulinemia and skin changes) is indentified as POEMS syndrome. The diagnosis of Castleman's disease was based on the results of histopathologic analysis of mediastinal lymph node biopsies after thoracotomy. The patient was treated with corticosteroids (prednisone 80 mg daily for 2 weeks followed by 60 mg daily). A partial response was achieved after 4 months of treatment.

CONCLUSION

A transitional type of multicentric Castleman's disease may be present itself as POEMS syndrome. The effect of corticosteroid therapy in this form of the disease is unpredictable.

Retrospective, longitudinal analysis of serum human herpesvirus-8 viral DNA load in AIDS-related Kaposi's sarcoma patients before and after diagnosis

Human herpesvirus 8 (HHV-8) is detected more often in patients progressing towards Kaposi's sarcoma (KS) than in patients who do not develop the disease, suggesting that the level of viremia might be associated with Kaposi's sarcoma disease and progression. Longitudinal serum samples from 19 AIDS-Kaposi's sarcoma patients, ranging from 2 years before KS till 2 years after KS diagnosis were tested. No correlation was found between viral load and progression to KS, or disease stage.

Castleman Disease of the Subcutis and Underlying Skeletal Muscle

Castleman disease of the subcutis and skeletal muscle is rare. We have collected a series of 6 cases of extranodal Castleman disease, located in the subcutis and skeletal muscles of the extremities and trunk. Tumors from mediastinal and retroperitoneal soft tissue and those histologically involving peripheral or truncal lymph nodes were excluded. There were four females and two males; ages ranged from 18 to 37 years (mean, 26 years). Locations included thigh (n = 3), anterior chest (n = 2), and upper arm (n = 1). Sizes ranged from 4.0 to 6.0 cm (mean, 5.2 cm). All patients presented with localized disease. One patient had involvement of the mediastinum 1 year prior to the appearance of his soft tissue lesion. None of the patients demonstrated systemic involvement or signs of the POEMS syndrome. Histopathologically, all cases were classified as hyaline-vascular type (HVCD). In 3 cases, follicular dendritic cell dysplasia was observed. In 1 case, the dysplasia was marked. The subcutaneous lesion of 1 patient revealed a maze of capillaries set in a lipomatous background with occasional lymphoid follicles possessing hyalinized lymphocyte-depleted centers. This lesion probably represented incipient HVCD. Molecular biologic studies did not reveal the presence of Epstein-Barr virus or human herpesvirus-8 DNA in the lesional tissue. There also were no monoclonal rearrangements of IgH. Four patients with follow-up included 2 patients with no evidence of disease at 10 and 13 years, respectively, and 2 patients with local recurrence at 2 and 6 months, respectively. In conclusion, soft tissue Castleman disease is a disease of young patients with a female predominance and a propensity to involve the trunk and limbs. It can be of large size and is generally solitary. There may be mild to marked follicular dendritic cell dysplasia. The HVCD predominates in this location. These lesions are usually unassociated with POEMS, Epstein-Barr virus, human herpesvirus-8, or monoclonal rearrangements of IgH.

Sarcoma of follicular dendritic cells in the dorsal mediastinum

Follicular dendritic cell sarcomas (FDCSs) are very rare and usually originate in lymph nodes. We report an exceedingly rare case with localization in the dorsal mediastinum and, for the first time, provide positron emission tomography (PET) data for this tumor. This report describes the case of a 76-year-old man with a clinically aggressive tumor in the dorsal mediastinum. Computed tomography scan revealed displacement of soft tissue and lymph nodes. PET showed that the tumor had a high proliferation rate. Investigation of the successfully removed tumor mass revealed reactivity of the tumor cells for follicular dendritic cell markers and desmosomes linking adjacent tumor cells at the ultrastructural level. Marked atypia, a high mitotic rate, and areas of coagulative necrosis were found. The tumor in our case revealed the typical features and thus was classified as FDCS. In contrast to previous reports in the literature, preoperative imaging, histology, and immunohistochemistry studies indicated at least an intermediate degree of malignancy. Nevertheless, the patient made a good postoperative recovery and remained apparently disease-free 2 years later.

Multicentric Castleman's disease and Kaposi's sarcoma in a cyclosporin treated, HIV-1 negative patient: case report

Background

Multicentric Castleman's disease (MCD) is a rare disease, but is more frequent in AIDS patients. MCD has only been reported twice before in patients receiving immunosuppressive therapy after renal transplantation, and never in patients receiving immunosuppressive therapy without transplantation. About half of the cases of MCD are human herpesvirus 8 (HHV8) – related, in contrast to Kaposi's sarcoma, a more common complication arising after immunosuppression, where the virus is found in virtually all cases.

Case presentation

We report a HIV-1 negative, non-transplant patient who developed HHV8-associated multicentric Castleman's disease and Kaposi's sarcoma after 17 years of immunosuppressive treatment with cyclosporin A for a minimal change nephropathy. Chemotherapy with liposomal doxorubicin resolved both symptoms of multicentric Castleman's disease and Kaposi's sarcoma in this patient. A concomitant decline in the HHV8 viral load in serum/plasma, as determined by a quantitative real-time PCR assay, was observed.

Conclusions

Multicentric Castleman's disease can be a complication of cyclosporin A treatment. Both multicentric Castleman's disease and Kaposi's sarcoma in this patient were responsive to liposomal doxorubicin, the treatment of choice for Kaposi's sarcoma at the moment, again suggesting a common mechanism linking both disorders, at least for HHV8-positive multicentric Castleman's disease and Kaposi's sarcoma.

HHV8 viral load measurements can be used to monitor effectiveness of therapy.

Epidermal growth factor receptor expression in follicular dendritic cells: a shared feature of follicular dendritic cell sarcoma and Castleman's disease

The factors regulating the growth of follicular dendritic cell (FDC) sarcoma are currently unknown. Using cDNA microarray analysis, we found that the epidermal growth factor receptor (EGFR) is expressed in FDC sarcoma. We immunohistochemically examined the expression of EGFR in a larger series of FDC sarcomas and in nonneoplastic FDCs. This included 8 cases of FDC sarcoma, 12 cases of hyaline vascular Castleman's disease (CD), 5 cases of human herpesvirus 8 (HHV8)-positive plasma cell CD, 7 cases of HHV8-negative plasma cell CD, 13 cases of reactive lymph nodes, 3 cases of reactive tonsils, 10 cases of follicular lymphoma, 6 cases of nodular mantle cell lymphoma, and 6 cases of angioimmunoblastic T-cell lymphoma. EGFR was expressed in tumor cells in 7 of 8 cases (88%) of FDC sarcoma (strongly in 4 cases and moderately in 3 cases). The single EGFR-negative case had an anaplastic appearance and a more aggressive clinical behavior. EGFR was also expressed by FDC in all types of CD (strongly in 4 cases, moderately in 16 cases, and weakly in 4 cases). Immunostaining results were negative or only weakly positive for EGFR in FDC of reactive lymph nodes and tonsils, and in the FDC networks of follicular lymphoma, mantle cell lymphoma, and angioimmunoblastic lymphoma. The up-regulation of EGFR in FDC of CD was paralleled by an increase in EGFR expression in the surrounding perifollicular fibroblastic reticulum cells suggesting coordinate regulation. These findings identify a differentially expressed growth regulatory receptor common to both FDC sarcoma and CD, identifying a target for possible therapy in unresectable or refractory cases.

Germinal centre-like versus undifferentiated stromal immunophenotypes in follicular lymphoma

Follicular dendritic cells (FDCs) in reactive germinal centres (GCs) show modulated expression of antigens indicative of step-wise maturation from more undifferentiated stroma. The present study compared the expression of FDC markers CD21, CD23, CD35, and chemokine CXCL13 and the stromal markers low-affinity nerve growth factor receptor (LNGFR) and CNA.42 in 35 follicular lymphoma (FL) cases with reactive lymphoic tissue. CXCL13 was expressed by follicular stroma in all FLs but most cases showed either partial (11/35 cases, 31%) or complete (10/35 cases, 29%) absence of other FDC antigens, most commonly CD23, followed by CD21 and CD35, with variable patterns of LNGFR and CNA.42 immunostaining. Only a minority of FL cases (14/35, 40%) showed stroma that resembled mature FDCs (CD23+, CD21+, CD35+) and these tumours were always associated with numerous intrafollicular T-cells, similar to reactive GCs. In the 25 FL cases that had identifiable extrafollicular tumour cells, the immunophenotype of follicular stroma showed the same variability but the extrafollicular stroma showed an absence of FDC markers, with the exception of frequent strong LNGFR staining. Stromal phenotypic changes in FL were not correlated with mean follicle size, percentage of diffuse growth, tumour mitotic rate or the proliferation index as determined by PCNA immunostaining. Serial biopsy specimens analysed in a subset of 15 patients showed either a stable stromal phenotype (seven cases, 47%) or loss of FDC antigens in tumour-associated stroma over time (seven cases, 47%). The GC-like subset of FLs, having both abundant intrafollicular T-cells and fully differentiated CD23+ FDCs, comprises a minority of FL cases that likely have different growth requirements from FLs that lack these features. The pattern of FDC antigen loss in stroma of FL is a readily assessable biological feature that appears independent of architectural growth pattern and may serve as a useful surrogate marker of tumour progression.