Castleman disease, also known as angiofollicular lymph node hyperplasia or giant lymph node hyperplasia, is an uncommon benign B-cell lymphoproliferative condition. It can affect several regions of the body but is commonly described as a solitary mediastinal mass.
There are two distinct subtypes of Castleman disease:
-
more common
localized, and locally treated
associated with minimal symptoms
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multicentric Castleman disease
usually in the context of HIV infection
systemic disease characterized by diffuse lymphadenopathy, anemia, splenomegaly, and systemic inflammatory symptoms
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Epidemiology
Unicentric Castleman disease typically occurs in children and young adults (3rd and 4th decades), with a slight female predominance (1.4:1) 15.
Multicentric Castleman disease, on the other hand, occurs in an older population (5th and 6th decades), with a slight male predominance 15. HIV is a relevant risk factor for this condition, and it has been demonstrated that all the HIV patients with multicentric Castleman disease are coinfected with the human herpesvirus 8 (HHV-8).
Associations
AIDS: especially multicentric 9
amyloidosis 10
Clinical presentation
Unicentric Castleman disease is usually asymptomatic and incidentally found on routine exams for other reasons. Depending on the anatomical site, a painless lymphadenopathy may be noted.
Multicentric Castleman disease has an exuberant clinical presentation due to the systemic inflammation, with symptoms such as fevers, night sweats, fatigue, and weight loss, and clinical signs of generalized lymphadenopathy, hepatosplenomegaly, and fluid retention.
Hematological abnormalities such as anemia, elevated inflammatory markers, hypergammaglobulinemia, and hypoalbuminemia are commonly found in patients with multicentric Castleman disease 15.
Pathology
The disease is of unknown etiology, but the most widely accepted theory is that Castleman disease is a chronic low-grade inflammatory process. The interleukin 6 in unicentric Castleman disease and both interleukin-6 and HHV-8 in multicentric Castleman disease are demonstrated to play a critical role in pathogenesis and symptomatology of the disease 15.
The disease is characterized by hypervascular lymphoid hyperplasia. There are also several recognized subtypes based on histopathology 1,2:
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hyaline vascular
most common ~90%, corresponding to most cases of the unicentric Castleman disease
most commonly found in the mediastinum
classically appears as an avidly enhancing mediastinal mass at CT and MRI
increased numbers of small hyalinised blood vessels within and between the lymphoid follicles, which show obliteration of the medullary sinuses
“onion-skinning” arrangement of the small lymphocytes of the mantle zones, forming concentric rings around the germinal center
-
plasma cell
often multicentric
hyperplastic follicles of varying sizes, which show patent medullary sinuses
less enhancing
may be more symptomatic 5
HHV-8–associated Castleman disease 8
multicentric Castleman disease not otherwise specified
Castleman disease is an exclusion diagnosis usually made by excisional biopsy of an affected lymph node. Alternatively, core needle biopsy can be performed when the excision is not possible 15.
Location
The distribution is as follows:
thorax: ~70%
abdomen/pelvis and retroperitoneum: 10-15%
neck: 10-15%
Multicentric Castleman disease may involve all of the above and is associated with a more complicated clinical course with systemic symptoms including fever and organomegaly.
Radiographic features
Plain radiograph
Thoracic lesions may present as mediastinal masses. Additional findings include the following 19:
displacement of adjacent structures due to mass effect
ipsilateral pleural effusion
periosteal reaction
Ultrasound
Both hyaline-vascular and plasma cell types present as hypoechoic masses and nodules 17. The ultrasonographic findings are non-specific and indistinguishable from other causes of lymphadenopathy. Doppler examination of hyaline-vascular type may reveal exuberant vascularity with predominantly peripheral flow, prominent penetrating feeding vessels entering the hilum, and low-resistance arterial wave pattern 18.
CT
For mediastinal lesions: CT chest
commonly seen as a solitary mediastinal mass, infiltrative mass, multiple lymph nodes or rarely as matted lymphadenopathy (with or without a dominant mass) in a single mediastinal compartment
typical arborising calcification may be seen within the mass in 15% of cases
hyaline vascular type typically shows intense homogeneous enhancement following contrast
dynamic CT demonstrates early rapid enhancement with washout in the delayed phase
plasma cell type are multicentric and are less enhancing 8
For abdominal lesions: CT abdomen
most commonly, a single well-defined abdominal mass
location is variable and includes retroperitoneum, mesentery, and porta hepatis 3
enhancement is homogeneous, or in larger lesions (>5 cm) may demonstrate central hypoattenuation consistent with necrosis
variable pattern of calcification, including arborising calcification
For multicentric disease: multi-region CT
bilateral hilar and mediastinal lymphadenopathy
centrilobular nodules
diffuse abdominal lymphadenopathy
hepatosplenomegaly
ascites
MRI
General signal characteristics include the following:
T1: iso to hyperintense relative to skeletal muscle
T1 C+ (Gd): shows enhancement
T2: arborising calcification may be seen as low signal
DWI/ADC: low ADC values may be encountered 13,14
Nuclear medicine
PET-CT
Small studies have shown that active Castleman disease is avid on FDG-PET 12. Discrimination between uni- and multicentric disease, mapping of the extent of disease and monitoring disease progression seems possible, especially if confirmed in larger series 7,12.
Treatment and prognosis
Treatment for unicentric Castleman disease is surgical, with a good prognosis (can be curative).
Multicentric Castleman disease may be treated with any combination of surgery, chemotherapy and prednisolone 6. Available treatments include also antiviral strategies (targeting HHV-8), and monoclonal antibody therapies targeting CD20 or IL-6 15. The prognosis is relatively poorer.
Patients with multicentric Castleman disease and POEMS syndrome are usually treated with high-dose immunosuppressive agents and steroids. If immunosuppression fails, autologous peripheral blood stem cell transplantation is recommended 19.
History and etymology
The condition was first described by an American pathologist, Benjamin Castleman (1906-1982) in 1954 4,20.
Differential diagnosis
For mediastinal lesions, consider the differential by location: