Idiopathic multicentric Castleman disease (iMCD)-idiopathic plasmacytic lymphadenopathy: A distinct subtype of iMCD-not otherwise specified with different clinical features and better survival.

Idiopathic multicentric Castleman disease (iMCD) is subclassified into iMCD-thrombocytopenia, anasarca, reticulin fibrosis, renal dysfunction, organomegaly (TAFRO) and iMCD-not otherwise specified (NOS) according to the Castleman Disease Collaborative Network (CDCN) consensus criteria. With a deeper understanding of iMCD, a group of patients with iMCD-NOS characterised by polyclonal hypergammaglobulinaemia, plasmacytic/mixed-type lymph node histopathology and thrombocytosis has attracted attention. This group of patients has been previously described as having idiopathic plasmacytic lymphadenopathy (IPL). Whether these patients should be excluded from the current classification system lacks sufficient evidence. This retrospective analysis of 228 patients with iMCD-NOS identified 103 (45.2%) patients with iMCD-IPL. The clinical features and outcomes of patients with iMCD-IPL and iMCD-NOS without IPL were compared. Patients with iMCD-IPL showed a significantly higher inflammatory state but longer overall survival. No significant difference in overall survival was observed between severe and non-severe patients in the iMCD-IPL group according to the CDCN severity classification. Compared with lymphoma-like treatments, multiple myeloma-like and IL-6-blocking treatment approaches in the iMCD-IPL group resulted in significantly higher response rates and longer time to the next treatment. These findings highlight the particularities of iMCD-IPL and suggest that it should be considered a new subtype of iMCD-NOS.

Insufficient evidence exists to use histopathologic subtype to guide treatment of idiopathic multicentric Castleman disease.

Idiopathic multicentric Castleman disease (iMCD) is a rare immunologic disorder characterized by systemic inflammation, multicentric lymphadenopathy, and organ dysfunction. Enlarged lymph nodes demonstrate a spectrum of characteristic but variable histopathologic features historically categorized into hyaline vascular (HV) (or hypervascular [HyperV] more recently), plasmacytic, or "mixed." Though the etiology is unknown, a pro-inflammatory cytokine storm, often involving interleukin-6 (IL-6), contributes to pathogenesis. Anti-IL-6 therapy with siltuximab is the only FDA- or EMA-approved treatment based on efficacy and safety in multiple studies. Importantly, no patients considered to have HV histopathology achieved the primary endpoint in the Phase II study. NCCN currently recommends siltuximab first-line for iMCD, except for patients considered to have HV histopathology. We investigated whether histopathologic subtype should guide siltuximab treatment decisions. Secondary analyses of clinical trial and real-world data revealed similar clinical benefit across histopathologic subtypes. Notably, only 18 of 79 patients in the Phase II study were consistently classified into histopathologic subtype by three independent review panels, demonstrating limited reliability to guide treatment decisions. Real-world data further demonstrate siltuximab's effectiveness in patients considered to have HV (or HyperV). Though histopathology is a critical component for diagnosis, there is insufficient evidence to guide treatment based solely on lymph node histopathologic subtype.

Epidemiological analysis of multicentric and unicentric Castleman disease and TAFRO syndrome in Japan.

Castleman disease is a polyclonal lymphoproliferative disease which is clinically classified into unicentric (UCD) and multicentric (MCD). TAFRO syndrome is a relatively new concept that partly overlaps with MCD. Due to their rarity, their incidence remains unknown. This study investigated the incidence and prevalence of UCD, MCD, and TAFRO syndrome in Japan using a fixed-point observation method based on their incidence in Ishikawa prefecture. The annual incidences of MCD, UCD, and TAFRO syndrome in Japan were 309-731, 71-542, and 110-502, respectively, yielding annual incidence rates per million individuals of 2.4-5.8, 0.6-4.3, and 0.9-4.9, respectively, and nationwide prevalence of 4,180-14,900, 1,350-10,300, and 860-7,240, respectively. In conclusion, MCD, UCD and TAFRO syndrome may not be as rare as previously estimated in Japan.

Is TAFRO syndrome a subtype of idiopathic multicentric Castleman disease?

Castleman disease (CD) is a rare lymphoproliferative disorder that can be unicentric or multicentric. Multicentric CD (MCD) is further subdivided into human herpesvirus type-8-associated, POEMS syndrome-associated, and idiopathic (iMCD). TAFRO syndrome is a newly identified disorder of unknown etiology characterized by thrombocytopenia, anasarca, fever, reticulin myelofibrosis, renal dysfunction, and organomegaly. The TAFRO syndrome is sometimes regarded as a subtype of iMCD (TAFRO-iMCD), whereas iMCD without TAFRO syndrome is considered "not otherwise specified" (iMCD-NOS). However, a proportion of patients with TAFRO syndrome have been diagnosed without lymph node biopsies (TAFRO syndrome without proven iMCD; TAFRO-w/op-iMCD). To clarify the clinical features of iMCD-NOS, TAFRO-iMCD, and TAFRO-w/op-iMCD, we retrospectively analyzed 220 patients extracted from the database of the Multicenter Collaborative Retrospective Study for Establishing the Concept of TAFRO Syndrome. The patients included 87 with iMCD-NOS, 63 with TAFRO-iMCD, and 19 with TAFRO-w/op-iMCD. Patients in all three groups exhibited anemia, hypoalbuminemia, and elevated serum C-reactive protein and interleukin-6 levels. No significant differences in clinical, laboratory, and prognostic features were noted between the TAFRO-iMCD, and TAFRO-w/op-iMCD groups. However, the iMCD-NOS group exhibited polyclonal hyper-γ-globulinemia. The five-year survival rates of patients in the iMCD-NOS and TAFRO-involved groups were 100% and 66.5%, respectively (dropping markedly during the first few months in the latter). The iMCD-NOS and the TAFRO-iMCD samples typically showed plasma cell and mixed-type histologies, respectively. Thus, iMCD can be classified into two distinct subtypes, iMCD-NOS and TAFRO-iMCD. As such, TAFRO-iMCD and TAFRO-w/op-iMCD may be considered the same entity, requiring prompt diagnosis and intensive care.

Thrombotic microangiopathy on kidney biopsy in a patient with TAFRO syndrome.

TAFRO syndrome represents a characteristic constellation of symptoms comprising Thrombocytopenia, Anasarca, myeloFibrosis, Renal dysfunction, and Organomegaly, and is considered to be a clinicopathologic variant of idiopathic multicentric Castleman disease. A 51-year-old woman was admitted to the hospital complaining of abdominal distension. Findings on physical examination were indicative of anasarca. Computed tomography revealed mild splenomegaly, pericardial effusion, pleural effusion, ascites, and paraaortic lymphadenopathy. Blood tests showed thrombocytopenia, and urinalysis demonstrated hematuria, proteinuria, and worsening renal function. Kidney biopsy was performed and revealed thrombotic microangiopathy-like lesions with global sclerosis of 1 of the 16 glomeruli on light microscopy. The remaining glomeruli had a distinct lobular pattern, with mesangiolysis, double contours of the glomerular basement membranes, and marked endothelial swelling. Immunofluorescence studies for IgG, IgM, IgA, C1q, C3, C4, κ-light chains, and λ-light chains were indeterminate. Electron microscopy showed marked endothelial swelling. We made a diagnosis of TAFRO syndrome and started steroid treatment, following which her symptoms gradually improved. There are few reports describing renal pathology in a patient with TAFRO syndrome.

Tentative diagnostic criteria and disease severity classification for Castleman disease: A report of the research group on Castleman disease in Japan.

OBJECTIVES: To determine the tentative diagnostic criteria and disease severity classification for Castleman disease (CD) and describe the clinical and pathologic features among human herpesvirus 8 (HHV-8) negative idiopathic multicentric CD (iMCD) in the Japanese population. METHODS: We established the working groups for the research of CD in Japan and had meetings to discuss and define the tentative diagnostic criteria and disease severity classification for CD. We subsequently analyzed 142 patients classified into iMCD by using the nationwide Japanese patient registry. RESULTS: We proposed the preliminary diagnostic criteria and disease severity classification for CD based on our discussion. In addition, we made a proposal for the disease activity score. We identified clinical and pathological features of patients with iMCD diagnosed by these diagnostic criteria. In the disease severity classification, 37, 33 and 30% patients were categorized into mild, moderate and severe diseases, respectively. CONCLUSION: This is the first proposal for diagnosis and classification of CD by the Japanese group. Further studies are required to validate whether they can distinguish CD from other inflammatory diseases and to determine their sensitivity and specificity.

Epidemiology of Castleman Disease.

Castleman disease is a rare entity, including unicentric Castleman disease (UCD), human herpesvirus-8 plus Castleman disease (HHV-8+MCD), and idiopathic multicentric Castleman disease (iMCD). UCD is the most common at 16 per million person years and occurs at every age. HHV-8+MCD incidence varies widely, mostly affecting human immunodeficiency virus-positive men. iMCD is likely a more heterogeneous disease with an estimated incidence of 5 per million person years. Improved definitions should improve understanding of the epidemiology of Castleman disease and its subtypes.

Pathology of Castleman Disease.

The term Castleman disease encompasses several distinct lymphoproliferative disorders with different underlying disease pathogenesis, and clinical outcomes. It includes unicentric and multicentric diseases with limited versus significant systemic symptoms, respectively. Importantly, the histopathologic features encountered in the various forms of Castleman disease are diverse, and for the most part, lack specificity, because they are seen to varying degrees in different clinical variants of Castleman disease, and in reactive (autoimmune/infectious) and malignant (lymphoma) contexts. Accordingly, accurate clinical diagnosis of Castleman disease requires careful and thorough clinicopathologic correlation. An overview of the key histopathologic features of Castleman disease is presented.

TAFRO syndrome: New subtype of idiopathic multicentric Castleman disease.

Castleman disease (CD) describes a group of three rare and poorly understood lymphoproliferative disorders that have heterogeneous clinical symptoms and common lymph node histopathological features. Unicentric CD (UCD) involves a single region of enlarged nodes. Multicentric CD (MCD) involves multiple regions of enlarged lymph nodes, constitutional symptoms, and organ dysfunction due to a cytokine storm often including interleukin 6. MCD is further divided into Human Herpes Virus-8 (HHV-8)-associated MCD, which occurs in immunocompromised individuals, and HHV-8-negative/idiopathic MCD (iMCD). Recently, iMCD has been further sub-divided into patients with TAFRO syndrome, which involves thrombocytopenia (T), anasarca (A), fevers (F), reticulin myelofibrosis (R), organomegaly (O), and normal or only slightly elevated immunoglobulin levels, and those who do not have TAFRO syndrome. Non-TAFRO iMCD patients typically have thrombocytosis, less severe fluid accumulation, and hypergammaglobulinemia. iMCD patients with TAFRO syndrome may have a worse prognosis, but more research is needed.

Diagnostic Utility of Interleukin-6 Expression by Immunohistochemistry in Differentiating Castleman Disease Subtypes and Reactive Lymphadenopathies.

The objective of the study was to evaluate the expression pattern of interleukin-6 (IL-6) to determine its utility in differentiating Castleman Disease subtypes and reactive lymphadenopathies. Paraffin-embedded tissue blocks from 20 cases referred for assessment of Castleman Disease (CD) and 4 cases of reactive hyperplasia were selected for immunohistochemical staining with an IL-6 antibody. Six pathologists evaluated the hematoxylin and eosin stained tissue sections and IL-6 expression pattern. Of 20 CD referral cases, the pathologic diagnosis was CD in 14 cases and included 6 hyaline-vascular (HV-CD), 6 plasma cell (PC-CD) and 2 "mixed type"-CD cases. The remaining 6 referral cases showed morphologic features consistent with reactive lymphadenopathy. Patients with non-CD, reactive lymphadenopathies had clinical and/or laboratory features of systemic lupus erythematosus, Hashimoto's disease, viral infection or chronic cellulitis. The pattern of IL-6 expression differed between CD subtypes and non-CD cases. In PC-CD, IL-6 expression was detected in plasma cells and vascular endothelial cells; whereas IL-6 immunoreactivity was detected primarily in vascular endothelial cells in HV-CD. Interfollicular plasma cells were prominent in PC-CD and reactive lymphadenopathies; however, IL-6 expression was significantly increased in PC-CD compared to reactive lymph nodes. Together with morphologic features, the expression pattern of IL-6 detected by immunohistochemistry is helpful to distinguish CD subtypes and reactive mimics.

Clinical spectrum and survival analysis of 145 cases of HIV-negative Castleman's disease: renal function is an important prognostic factor.

Castleman's disease (CD) is a rare lymphoproliferative disorder with clinical features and prognostic factors that are incompletely characterized. This retrospective single-center study reviewed the largest HIV-negative CD patient cohort (n = 145) to date. By clinical classification, we identified 69 patients (47.6%) as unicentric CD (UCD) and 76 patients (52.4%) as multicentric CD (MCD). Pathological classification identified 74 patients (51.0%) with the hyaline-vascular variant, 51 patients (35.2%) with the plasma-cell variant, and 20 patients (13.8%) with a mixed variant. After a median follow-up duration of 58 months (range, 1-180 months), the 1-year and 5-year survival rates were 95.1% and 91.0%, respectively. UCD patients exhibited significantly better survival (1-year and 5-year survival rates of 98.5% and 97.1%, respectively) compared with MCD patients (1-year and 5-year survival rates of 92.1% and 85.5%, respectively; p = 0.005). By univariate and multivariate Cox regression analyses, the estimated glomerular filtration rate < 60 ml/min (with the MDRD equation; hazard ratio = 4.60; 95% confidence interval, 1.50-14.12; p = 0.008) was clinically significant and represented an independent predictor for death in MCD patients. In summary, this large-scale study suggests that UCD patients enjoy better survival than MCD patients and that renal function is an important prognostic factor for MCD patients.

Proposed diagnostic criteria, disease severity classification and treatment strategy for TAFRO syndrome, 2015 version.

TAFRO syndrome is a systemic inflammatory disorder characterized by thrombocytopenia, anasarca including pleural effusion and ascites, fever, renal insufficiency, and organomegaly including hepatosplenomegaly and lymphadenopathy. Its onset may be acute or sub-acute, but its etiology is undetermined. Although several clinical and pathological characteristics of TAFRO syndrome resemble those of multicentric Castleman disease (MCD), other specific features can differentiate between them. Some TAFRO syndrome patients have been successfully treated with glucocorticoids and/or immunosuppressants, including cyclosporin A, tocilizumab and rituximab, whereas others are refractory to treatment, and eventually succumb to the disease. Early and reliable diagnoses and early treatments with appropriate agents are essential to enhancing patient survival. The present article reports the 2015 updated diagnostic criteria, disease severity classification and treatment strategy for TAFRO syndrome, as formulated by Japanese research teams. These criteria and classification have been applied and retrospectively validated on clinicopathologic data of 28 patients with this and similar conditions (e.g. MCD with serositis and thrombocytopenia).

Doença de Castleman cervical: relato de três casos / Cervical Castleman's disease: report of three cases

A doença de Castleman (DC) é uma rara e benigna desordem linfoproliferativa descrita por Castleman como "hiperplasia hialinizante linfoide". Sua etiologia e patogênese é desconhecida, porém parece haver hiperestimulação antigênica induzida por vírus de forma crônica e mediada por interleucina 6, com alguns casos ligados ao herpes vírus 8 e vírus da imunodeficiência humana (AU)

Castleman's disease (CD) is a rare and benign lymphoproliferative disorder described by Castleman as "hyelinizing lymphoid hyperplasia". Its etiology and pathogenesis are unknown, but there appears to be antigen hyperstimulation chronically induced by virus and mediated by interleukin 6, with some cases related to herpes virus 8 and human immunodeficiency virus (AU)

[Multicentric hyaline vascular Castleman's disease. A POEMS type variant]. / Enfermedad de Castleman multicéntrica hialina vascular. Una variante de POEMS.

BACKGROUND: Castleman's disease is an atypical lymphoproliferative disorder which may be compatible with paraneoplastic manifestations of POEMS syndrome. CLINICAL CASE: a 53 year old man with a history of type 2 diabetes, hypothyroidism and Addison's disease presented with numbness and weakness in limbs, dyspnea, skin hardening, Raynaud's phenomenon, weight loss and fatigue. A physical exam showed tachypnea, generalized cutaneous hyperpigmentation and skin hardening of extremities, muscle weakness, hypoesthesia and hyporeflexia. Laboratory showed hyperprolactinemia, low testosterone, hypothyroidism and Addison's disease. Electrophoresis of proteins showed polyclonal hypergammaglobulinemia. Somatosensory evoked potentials reported peripheral neuropathy and severe axonal polyneuropathy by electromyography. Chest X-rays showed bilateral reticular infiltrates and mediastinal widening. An echocardiogram displayed moderate pulmonary hypertension. Skin biopsy had no evidence of scleroderma. CT reported axillar, mediastinal and retroperitoneal nodes. The mediastinal lesion biopsy reported hyaline vascular Castleman's disease, multicentric variety. He was treated with rituximab. CONCLUSIONS: the case meet criteria for multicentric hyaline vascular Castleman's disease, POEMS variant, treated with rituximab.

Introducción: la enfermedad de Castleman es un trastorno linfoproliferativo atípico en el que pueden existir manifestaciones compatibles con síndrome POEMS. Caso clínico: hombre de 53 años de edad con antecedente de diabetes mellitus tipo 2, hipotiroidismo y enfermedad de Addison. Se iniciaron parestesias y debilidad en las extremidades y, posteriormente, disnea, endurecimiento cutáneo, fenómeno de Raynaud y pérdida de peso. Se identificó taquipnea, hiperpigmentación cutánea generalizada y extremidades con endurecimiento cutáneo, debilidad muscular, hipoestesia e hiporreflexia; así como hiperprolactinemia, testosterona baja, hipotiroidismo y enfermedad de Addison; los anticuerpos antinucleares y antiScl-70 fueron negativos. Los potenciales evocados somatosensoriales indicaron neuropatía periférica y la electromiografía, olineuropatía axonal severa. Radiografía torácica: infiltrado reticular bilateral y ensanchamiento mediastinal. Electrocardiograma: hipertensión arterial pulmonar moderada. Tomografía toracoabdominal: ganglios axilares, mediastinales y retroperitoneales. Con la biopsia se identificó enfermedad de Castleman multicéntrica hialina vascular. El paciente recibió rituximab. Conclusiones: si bien la experiencia con el rituximab aún es limitada, en el caso descrito se observó buena respuesta.

Multicentric Castleman's disease: a challenging diagnosis.

Multicentric Castleman's disease (MCD) is a sytemic disorder with flares of non-specific symptoms suggestive of a chronic inflammatory syndrome. It is typically accompanied by generalized lymphadenopathy and multiorgan involvement. Histologically, two main variants of Castleman's disease exist, the hyalin vascular type and the plasma cell variant. Upon localization unicentric (localized), and multicentric (diffuse, systemic) subtypes can be distinguished with more different disease outcomes. Patients often exhibit acute phase reactions and several autoimmune phenomena, and are at high risk for developing malignancies. Both the idiopathic and the HHV-8-driven infectious forms of MCD represent distinct disease entities with a less favorable prognosis. The induction of human IL-6 excess via yet unknown upstream mechanisms, and overexpression of viral IL-6 by HHV-8 can pivotally influence MCD biology. Based on the role of IL-6 in pathogenesis, MCD is also designated as IL-6 lymphadenopathy. To date there are no direct therapeutic evidences, but having been translated to daily practice the main regulatory factors may serve as promising therapeutic targets.

Castleman disease: the great mimic.

Castleman disease is a nonclonal lymphoproliferative disorder and one of the more common causes of nonneoplastic lymphadenopathy. Because of its diverse manifestations and ability to affect any body region, Castleman disease is a great mimic of both benign and malignant abnormalities in the neck, chest, abdomen, and pelvis. Castleman disease most commonly manifests as unicentric disease (unicentric Castleman disease) with a hyperenhancing lymph nodal mass and should be considered in the differential diagnosis of lymphoma, metastatic adenopathy, and infectious and/or inflammatory diseases that result in adenopathy. Castleman disease includes a spectrum of pathologic variants, including the classic hyaline vascular type, the less common plasma cell variant of Castleman disease, and the more recently described multicentric Castleman disease and Castleman disease associated with human herpesvirus 8. Castleman disease has been associated with the human immunodeficiency virus, lymphoma, POEMS (polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) syndrome, paraneoplastic pemphigus, and plasma cell dyscrasias. Aggressive forms of Castleman disease with systemic manifestations may occur. Unicentric hyaline vascular Castleman disease is often curable with surgery; however, multicentric Castleman disease may require steroid treatment, chemotherapy, antiviral medication, or the use of antiproliferative regimens because a surgical procedure cannot be curative in this setting. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.316115502/-/DC1.

Castleman's disease: systematic analysis of 416 patients from the literature.

BACKGROUND: Castleman's disease is a rare primary disease of the lymph nodes with limited available clinical information. METHODS: A systematic literature search identified 416 cases amenable to detailed analysis. RESULTS: In HIV(-) patients, centricity, pathology type, the presence of symptoms, gender, and age all predict outcome in univariate analyses. The 3-year disease-free survival (DFS) rate for patients with unicentric hyaline vascular disease (49.5% of cases, class I) was 92.5%, versus 45.7% for those with multicentric plasma cell disease (20.2% of cases, class III) and 78.0% for those with any other combination (22.6% of cases, class II) (p < .0001). HIV(+) patients (class IV) exclusively presented with multicentric plasma cell disease and had a 3-year DFS rate of only 27.8%. Kaposi's sarcoma and lymphoma were observed in 59.3% and 9.4% of HIV(+) patients and in 2.6% and 3.6% of HIV(-) patients (p < .0001). Paraneoplastic pemphigus and the syndrome of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes were observed exclusively in HIV(-) patients at a rate of 1.3% and 1.8%, respectively. CONCLUSION: Clinical, pathological, and viral markers allow for the classification of Castleman's disease into groups with markedly different outcomes and disease associations.

Comparison of plasma cell type of Castleman's disease and IgG4-related sclerosing disease: a histopathological and immunohistochemical study.

OBJECTIVES: Castleman's disease (CD) is a group of rare atypical lymphoproliferative disorders classified as hyaline vascular (HV) and plasma cell (PC) types. CD may be closely mimicked by IgG4-related sclerosing disease (IgG4-SD) involving the lymph nodes. We retrospectively analyzed findings in patients with CD to elucidate the relationship between CD and IgG4-SD. METHODS: Clinicopathological and immunophenotypical characteristics, including IgG+ and IgG4 expression by plasma cells, were analyzed in 87 consecutive patients diagnosed with CD from 1999 to 2010 at two major Korean hospitals. RESULTS: The numbers of IgG+ (p < 0.001) and IgG4+ (p < 0.001) cells and the IgG4:IgG ratio (p = 0.003) were significantly higher in the PC than in the HV group. The mean IgG4+:IgG+ plasma cell ratio in the PC group was 25.1%, with 10 patients having a ratio >40%, the threshold IgG4:IgG ratio in patients with IgG4-SD. CONCLUSIONS: Patients with the PC form of CD and IgG4-related lymphadenopathy share some features, including the pattern of plasma cell distribution and high-level infiltration of IgG4+ cells. Some patients thought to have the PC form of CD could be reclassified as showing IgG4-related lymphadenopathy.

Doença de Castleman associada a sarcoma de células dendríticas foliculares e miastenia gravis / Castleman's disease associated with follicular dendritic cell sarcoma and myasthenia gravis

A doença de Castleman é um distúrbio linfoproliferativo atípico, de etiologia desconhecida, que pode estar associada a uma série de condições clínicas, inclusive doenças de caráter autoimune e neoplasias malignas. No presente relato, uma paciente de 72 anos foi encaminhada ao serviço de cirurgia torácica do Hospital Universitário Getúlio Vargas, localizado na cidade de Manaus (AM) para a ressecção de um tumor de mediastino posterior. Três meses antes, havia sido internada em UTI com um quadro de dispneia intensa, ocasião na qual foi diagnosticada miastenia gravis. Após a ressecção da massa mediastinal, a análise histopatológica revelou doença de Castleman hialino-vascular complicada por sarcoma de células dendríticas foliculares. Até o momento da redação deste estudo, a paciente utilizava um anticolinesterásico e corticoides para o controle da miastenia gravis.

Castleman's disease is an atypical lymphoproliferative disorder of unknown etiology, which might be associated with various clinical conditions, including autoimmune diseases and malignant neoplasms. We report the case of a 72-year-old female patient who was referred to the thoracic surgery department of Getúlio Vargas University Hospital, in the city of Manaus, Brazil, for the resection of a posterior mediastinal tumor. Three months prior, the patient had been admitted to the ICU with signs of severe dyspnea, at which time she was diagnosed with myasthenia gravis. After the resection of the mediastinal tumor, the histopathological examination revealed hyaline vascular-type Castleman's disease, complicated by follicular dendritic cell sarcoma. At this writing, the patient was being treated with an anticholinesterase agent and corticosteroids for the control of myasthenia gravis.