Granulomatous inflammatory pseudotumor of the spleen: association with Epstein-Barr virus.

A 74-year-old woman with a clinical history of invasive ductal carcinoma of the breast was found to have a splenic mass during a routine radiographic survey. Splenectomy revealed a 3-cm well-demarcated lesion, which on histopathologic examination consisted of heterogeneous inflammatory cells. A striking feature of the lesion was the presence of innumerable well-formed non-necrotizing granulomas. Immunohistochemical studies confirmed the lesion to be composed mainly of mixed T and B lymphocytes, histiocytes, and plasma cells. No spindle cell component was evident on light microscopic examination or by immunohistochemical staining for smooth muscle actin, anaplastic lymphoma kinase, or follicular dendritic cell markers CD21 and CD35. Interestingly, Epstein-Barr virus-encoded RNA and latent membrane protein were detected by in situ hybridization and immunohistochemistry in numerous lymphohistiocytic cells within the lesion, but not in surrounding uninvolved splenic tissue. To our knowledge, this case represents a rare example of splenic inflammatory pseudotumor with exuberant granulomatous reaction in association with Epstein-Barr viral infection.