Castleman disease lymphadenopathy in the Era of HIV. Pitfalls in diagnosis and their avoidance

Castleman disease and HIV-lymphadenitis share similar morphologies, but they can be identified separately. We retrospectively studied 16 cases diagnosed as Castleman disease over a seven-year-period. Four HIV-infected patients (two men and women) with lymphadenitis and 10 Castleman disease cases were obtained. All patients with Castleman disease had unicentric disease except one with multicentric variety. All had characteristic follicular morphologies and four of them also had interfollicular changes. The HIV-lymphadenites showed similar follicular morphologies except for conspicuous concentric ringing in the broadened mantle zone. Additionally, in the interfollicular region, plasmacytoid cells were found. None of the Castleman disease recurred after surgery, except the multicentric case who continue to suffer and is currently being treated with chemotherapy. The remaining two cases were one each of follicular lymphoma and follicular hyperplasia. Castleman disease is a well-defined lymphadenopathy characterized by small follicles, diminished sinuses, broadened mantle zones with concentric ringing of lymphocytes around hyalinized germinal centers composed of follilcular dendritic cells. HIV-lymphadenitis progresses from follicular hyperplasia to a hyalinized, fibrotic node with sclerotic germinal centers, plasma cells and marked angiogenesis. In spite of numerous similarities, pathologists should not confuse one with the other because treatment implications are grave. A thorough clinical history aids in diagnosis.