Development of vascular neoplasia in Castleman's disease. Report of seven cases.

Seven cases of vascular neoplasia arising within lesions of hypervascular follicular hyperplasia (HFH) fulfilling the criteria of Castleman's disease are described. The patients did not have evidence of acquired immunodeficiency syndrome or other immunologic disorders. The masses were solitary and located in the retroperitoneum (five cases), mediastinum (one case), and axilla (one case). Grossly, they measured up to 20 cm and had a variegated appearance. In each case two morphologically distinct processes were present: a mesenchymal spindle-cell neoplasm with evidence of vascular differentiation and Castleman's disease of hyaline vascular type. The two processes blended with each other, with the neoplasm appearing to be continuous with the interfollicular proliferation of small vessels that is typical of Castleman's disease. The lesions behaved aggressively in two cases, both patients having died with metastatic disease. This remarkable association may be viewed as a pathologic manifestation of the intimate functional relationship that exists between the immune and the vascular systems. Other probable examples of this relationship are systemic Castleman's disease associated with Kaposi's sarcoma, localized Castleman's disease associated with vascular hamartoma, histiocytoid hemangioma/angiolymphoid hyperplasia with eosinophilia, and (possibly) angiomatoid malignant fibrous histiocytoma. Perhaps these associations are mediated by the production of angiogenic factors by the activated lymphoid cells.