[High-degree malignancy non-Hodgkin's lymphoma simulating a disseminated carcinoma. Presentation of 2 cases]

Highly malignant non-Hodgkin lymphomas (HM-NHL) may sometimes develop clinical features simulating an epithelial carcinoma with metastatic dissemination. Conventional histopathological study may be insufficient to differentiate between both conditions. Two patients with HM-NHL are reported with a rapid general deterioration; one of them had osteolysis and hypercalcemia. In both cases a diffuse bone marrow infiltration by large sized cells with blastic appearance was found. The initial suspected diagnosis was occult epithelial neoplasia with metastatic dissemination. The morphological study with optic microscopy and the ultrastructural analysis did not establish the origin of these cells. The definitive diagnosis was obtained by immunohistochemical techniques. In both cases, the cells were positive for the CD 45 (common leukocyte antigen) monoclonal antibody (MoAb), and for several MoAbs of lymphoid B differentiation. In one of them, the B lymphoid lineage was confirmed by monoclonal reordering of the gene that synthetises the immunoglobulin heavy chain.