Castleman's disease is a rare cause of strikingly uniform enhancing lymph nodes. Castleman's disease (also referred to as angiofollicular lymph node hyperplasia) is a specific type of lymph node hyperplasia of uncertain aetiology which can cause substantial lymph node enlargement in many sites in the body. The lymph node mass is often localised to one area, can be huge and may be very vascular. The nodes may calcify and may show striking contrast media enhancement on both CT and MRI (Fig. 1). Histologically, there are two types: the hyaline vascular type and the plasma cell type.

In addition to Castleman's disease, marked lymph node enhancement may occur in hypervascular metastases from melanoma, renal cell carcinoma, carcinoid tumours, papillary thyroid cancer and Kaposi's sarcoma.

Contrast media enhancement of enlarged nodes, when moderate in degree, is non-specific, being seen with inflammatory disorders, particularly tuberculosis, fungal disease, sarcoidosis and neoplasm. A low-density centre with rim enhancement of the enlarged node is a useful pointer towards the diagnosis of tuberculous or other granulomatous infections.

FIGURE 1 ■ Castleman's disease. A 33-year-old woman with shortness of breath was further evaluated by contrast mediumenhanced CT. Transaxial CT images show a normal thyroid (A), but narrowing and displacement of the trachea by a heterogeneously enhancing mediastinal mass located more inferiorly (B). The mass was surgically excised and pathological examination revealed hyaline vascular type of Castleman's disease.

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