The great mimickers: Castleman disease.

Castleman disease (CD) was first described and most commonly occurs in the form of classic hyaline-vascular-type CD with hyperenhancing localized (unicentric) nonneoplastic lymphadenopathy. CD may affect any body region including unusual locations for isolated lymph node enlargement. This makes CD a great mimicker of more common benign and malignant masses in the neck, chest, abdomen, and pelvis. CD masses commonly raise the suspicion of lymphoma, paraganglioma, neuroendocrine tumor, metastatic adenopathy, solid parenchymal tumors, and infectious or inflammatory diseases. The less common plasma cell-type CD, mixed CD, and human herpes virus-8-associated CD (HHV8-CD) are more prone to lead to generalized (multicentric) adenopathy without the typical nodal hyperenhancement and are associated with B symptoms and hematologic and immunologic manifestations. The generalized forms of CD have a worse prognosis, which can approach that of malignancies. CD has multiple known associations with neoplasms, skin diseases, blood dyscrasias, and immunodeficiency, which include certain forms of lymphoma; paraneoplastic pemphigus; polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes syndrome; and plasma cell dyscrasias. Cytokine overproduction (IL-6) is an important pathogenetic factor in the development of CD. The treatment is accordingly variable, from curative or diagnostic resection of a solitary lesion to systemic chemotherapy or anti-IL-6 therapy.