Heterogeneity of systemic extra-nodal Epstein-Barr virus-associated lympho-histiocytic tumor--ten autopsy cases of human immunodeficiency virus-negative Japanese.

Epstein-Barr virus associated T-Cell lymphoma mimicking malignant histiocytosis (MH) has been previously reported. We selected 10 autopsy cases of extranodal lymphoma or histiocytic tumor, which showed an EBV presence in the tumor cells as well as a fulminant clinical course. The detailed clinicopathologic features were thus clarified. A retrospective study was performed on ten adult patients, eight males and two females, and almost all cases presented with a fulminant clinical course, revealing pancytopenia, liver dysfunction and disseminated intravascular coagulopathy. Immunophenotypic and genotypic studies along with in situ hybridization (ISH) were performed. The autopsy findings mainly showed extra nodal involvement in the liver (10 patients), spleen (9 patients), intestinal tract (5 patients), bone marrow (5 patients), nasal cavity, lungs, adrenal glands, kidneys (2 patients) and brain. Histologically atypical pleomorphic lymphoid cells were observed to infiltrate with reactive histiocytes, some of which showed hemophagocytosis. Based on the histological and clinical findings, diagnosis of malignant histiocytosis was made. ISH showed an EBV-presence in almost all the tumor cells. The immunophenotype and/or genotype studies demonstrated T-cell lymphoma (2 patients), Histiocytic tumors (2 patients), B-cell lymphoma (1 patients), natural killer (NK) cell lymphoma (3 patients), and T/NK lymphoma (2 patients), in which T or NK could not be confirmed, due to a lack of fresh materials. Based on the above findings, the histological appearance of EBV-associated MH previously defined was shown to be common to extra-nodal malignant lymphomas having origin in various organs, although the cytological and genetic features were heterogenous.