Á¤´ä: Castleman's disease
Solitary mass in the pretracheal region has hypodense centre and enhancing rim. This patient has no malignancy. Differential diagnosis would include primary tumour, metastatic lymph node.
Castleman disease, also known as angiofollicular hyperplasia or giant lymph node hyperplasia, is a rare disorder of lymphoid tissue. This disease may occur anywhere along the lymphatic chain but it is most commonly found as a solitary mass in the mediastinum.
Castleman's disease (CD, angiofollicular lymph node hyperplasia) is a lymphoproliferative disorder associated with infection from the human immunodeficiency virus (HIV) and human herpesvirus 8 (HHV-8). CD comprises at least two distinct diseases (unicentric and multicentric) with very different prognoses. Both conditions can be associated with development of malignancies, such as non-Hodgkin lymphoma.
¡× Unicentric Castleman¡¯s disease ¦¡ Unicentric (localized) CD is most often an isolated asymptomatic lymphoproliferative disorder of young adults. The vast majority of lesions are in the mediastinum and lung. Peripheral lymphadenopathy is unusual and laboratory and clinical abnormalities are seen in less than 25 percent of cases.
¡¤ Complete resection of the involved node should be performed whenever possible, rather than simple biopsy or incomplete resection. Such treatment is universally curative, with no relapses reported to date.
¡¤ If the involved node cannot be completely removed because of its anatomic location, localized radiation therapy can be employed, but is curative in less than 50 percent of cases.
¡× Multicentric Castleman¡¯s disease ¦¡ Patients with multicentric Castleman's disease (MCD) present at a median age between 52 and 65 with fever, night sweats, weight loss, and weakness or fatigue. Peripheral lymphadenopathy is nearly universal, generalized, and often accompanied by hepatosplenomegaly. Laboratory abnormalities include anemia, hypoalbuminemia, hypergammaglobulinemia, and an elevated sedimentation rate.
¡¤ The prognosis of untreated MCD is poor. Median survival was 26 to 30 months and 8 to 14 months in the pre- and post-HIV eras, respectively.
¡¤ Almost all treatments using single agents (eg, anti-viral, anti-cytokine, chemotherapy, corticosteroids) are palliative, with disease recurrence once they are stopped.
¡¤ For most symptomatic patients without evidence for organ failure, we suggest the use of the monoclonal antibody rituximab over single agent therapy or combination chemotherapy such as CHOP or CVAD (Grade 1B). Such treatment has resulted in two-year overall and relapse-free survival rates of 94 to 95 percent and 79 to 85 percent, respectively.
¡¤ For those patients with evidence of organ failure or poor performance status, we suggest the addition of a chemotherapeutic agent to treatment with rituximab (Grade 2C). Experience is greatest with etoposide 100 mg/m2 intravenously for four weeks, although several case reports have described success with CHOP without rituximab. CHOP with rituximab has not yet been studied in MCD.
Two distinct histologic patterns of Castleman disease have been described, including the hyaline-vascular type, accounting for 90% of cases, and the remainder of cases as the plasma cell type, which is often associated with constitutional symptoms.
Three patterns have been reported on CT or MRI, including a solitary noninvasive mass (50%), a dominant infiltrative mass with associated lymphadenopathy (40%), and a matted lymphadenopathy without a dominant mass (10%).
In Castleman disease, CT with contrast material usually shows a dense uniform enhancement. Dynamic CT demonstrates early rapid enhancement and washout in the delayed phase, which are considered as typical imaging characteristics that help to differentiate this disease from other mediastinal tumors, furthermore, peripheral hypervascularity is a characteristic finding on power Doppler ultrasonography. A punctate or arborizing pattern of calcification may be seen.
Some recent studies have reported a considerable number of cases showing heterogeneous attenuation. They reported that tumors greater than 5 cm in diameter generally demonstrate heterogeneous enhancement. In several studies, a focal low attenuation area within the mass showing delayed enhancement on dynamic CT or MRI, was pathologically proven to be central stellate fibrosis interspersed within the mass.
An MRI study has been reported to be useful for the evaluation of peripheral or tumoral hypervascularity and the relationship with adjacent vascular structures, because vascular structures appear signal void with high contrast to the mass. In the present case, double inversion recovery, so called black blood imaging with T1- or T2-weighted images, excellently demonstrated peripheral dilated and tortuous vascular structures.
