Castleman disease is a rare disorder of the lymphoid system characterized by noncancerous growths that may develop in lymph node tissues throughout the body. Most often this occurs in the neck, mediastinum, and abdomen where lymph nodes aggregate. Here we describe a case of asymptomatic intrapulmonary Castleman disease adjacent to the left pulmonary hilum that mimicked central pulmonary malignancy in a 27-year-old man who underwent curative surgical removal of the mass.
A 27-year-old man was referred to our department for a mass in his left lung revealed by routine X-ray examination. He did not have any symptoms. His cigarette index was 200 (10 years, 20 cigarettes/day). On admission to the hospital, physical examination revealed nothing abnormal, and his laboratory data were within normal limits. Chest computed tomography showed a 7.5-cm × 5.5-cm, irregular, well defined, contrastenhanced mass with central necrosis in the left pulmonary hilar region (Figure 1). Fiberoptic bronchoscopy showed nothing abnorma l, but pulmonary malignancy could not be ruled out. The tumor screening examinations, including abdominal sonography, technetium-99m whole-body bone scan, and cranial computed tomography were performed with negative results. A left thoracotomy was performed, and the tumor lesion was located in the oblique fissure adjacent to the left pulmonary hilum. The lesion was highly vascularized, and it adhered closely to the pulmonary artery supplying the left lower lobe and the left lower lobe bronchus. Fortunately, the lesion had an almost intact capsule. Given the patient's age, great efforts were made to divide the adhesion between the lesion and the surrounding structure in order to avoid a pneumectomy. The lesion was finally cored out, while the lung tissue was reserved, although blood loss was significant, and blood infusion was required.
Pathologic examination showed hyaline follicles with interfollicular capillary proliferation (Figure 2). On immunohistochemical staining, the hyperplastic cells were positive for CD3, CD5, L26, CD79, UCHL-1, and Vimentin and negative for cytokeratin (CK). The result was compatible with the diagnosis of Castleman disease (hyaline vascular type). The postoperative course was uneventful, and the patient was discharged at postoperative day 8 with the anemia improved.
Castleman first reported the appearance of giant lymph node hyperplasia in the mediastinum in 1954. Since then, many synonyms have been linked to Castleman disease, including angiofollicular lymph node hyperplasia, giant lymph node hyperplasia, lymph node hamartoma, angiomatous lymphoid hyperplasia, and benign giant lymphoma. The disease can be found in the neck (42%), mediastinum (31%) and abdomen (23%).1 The exact etiology remains unclear, but theories include reactive lymphoid hyperplasia, hamartomatous change, benign lymphoid tumor, and inflammatory or infectious reactions of the lymph nodes.
Now Castleman disease is classified histologically as two types: the hyaline vascular type and the plasma-cell type. Most (90%) cases of Castleman disease are of the hyaline vascular type, which are characterized by the presence of small hyaline follicles with interfollicular capillary proliferation. The hyaline vascular type of disease is typically asymptomatic, clinically manifests as a slow-growth mass, and presents as isolated lesions found on routine chest radiographs, just as in this case. The plasma-cell type is characterized by the presence of large follicles with interposed sheets of plasma cells. These tumors, in contrast to the hyaline vascular type, typically present with systemic symptoms of fever and night sweats. The consensus opinion is that the plasma-cell variety represents a more aggressive form of the disease. It was reported that the plasma-cell type is frequently accompanied by immunodeficiency, infection, Kaposi's sarcoma (13%), non-Hodgkin lymphoma (18%), glomeruloid hemangioma, plasmacytoma, carcinomas of the colon, kidney, and thyroid, mixed connective tissue disease, polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes, with the latter five items also known as POEMS syndrome.2 In recent years a multicentric (generalized) type has been shown to exist as generalized lymphadenopathy with the morphologic features of giant lymph node hyperplasia. This type affects many areas of the body. The symptoms may be similar to those of the plasma-cell type and may include hepatosplenomegaly. Individuals with multicentric Castleman disease tend to be older (50 to 70 years of age). Considerable interest is currently being focused on the role of human herpesvirus-8 in this lesion.3 The multicentric form of the disease is quite virulent compared with the typically benign course of classic Castleman disease. Mortality has been reported to be as high as 50%, most commonly due to overwhelming sepsis.
Diagnosis of Castleman disease is difficult because of its rare incidence and nonspecific clinical features and results of radiological examination, and definite diagnosis depends on tissue histology. To avoid misdiagnosis, Castleman disease should be included in the preoperative differential diagnosis. The computed tomography may reveal a well-defined, localized mass with striking contrast enhancement that is usually not seen in lymphoma or thymoma. Preoperative angiographic embolization can reduce intraoperative bleeding significantly and make surgery much easier. Scintigraphy may not be able to differentiate Castleman disease from malignant tumors, but it is important in excluding the presence of multicentric disease.
Localized Castleman disease requires surgery, and complete surgical excision allows full recovery in almost all cases.4 When resecting a Castleman tumor of the hyaline vascular type, great care must be taken because of its extreme vascularity. Resection of this variety is often associated with significant intraoperative blood loss. Adjunctive radiotherapy could be an option in patients at high risk of recurrence or unsuitable for surgery.5 Corticosteroid and anti-neoplastic chemotherapy are suitable for the multicentric type, although research has not identified a standard or best treatment because of its extremely rare incidence.
In this case, Castleman disease presented as a well defined mass, located adjacent to the hilum in a young man. All preoperative data and analysis of risk factors, including the CT imaging, indicated a low probability of malignancy, except for the diameter of the lesion (>4 cm); but it is difficult to make a definite diagnosis before surgical biopsy. To avoid misdiagnosis, Castleman disease should be included in the differential diagnosis of a lung mass with striking contrast enhancement and well defined margin near the pulmonary hilum in a young adult presenting as isolated lesions found on routine chest radiographs.
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