Primary Follicular Large Cell Lymphoma of the Testis in a Child

Primary follicular lymphoma of the testis in childhood is extremely rare. To our knowledge, only 5 cases have been reported to date. We report a case in a 6-year-old boy who presented with painless right scrotal enlargement. Right radical orchiectomy revealed a follicular large cell lymphoma with diffuse areas confined to the testis and epididymis, clinical stage IE. Immunohistochemical stains demonstrated that the neoplastic cells were of B-cell lineage, positive for CD10, CD20, CD79a, and BCL-6. Staining for CD21 accentuated networks of dendritic reticulum cells within the nodules. The cells were negative for BCL-2, p53, and T-cell antigens. There was no evidence of the t(14;18) detected by polymerase chain reaction. The data suggest that follicular lymphoma of the testis in children has a different pathogenesis than follicular lymphoma in adults.

S-100 Protein Detection in “Follicular Macrophages” of Mouse Lymphoid Organs by ABC Immunoperoxidase Method

The distribution of S-100 protein was investigated in normal or reactive lymphoid organs from adult mice, rats and humans by the avidin-biotin complex ABC) immunoperoxidase method. In mouse lymph nodes and spleen the protein appeared to be confined to the “tingible-body macrophages” and occasionally in sinus histiocytes in the lymph nodes. No immunoreaction product was detected in the other cell types present inside or outside the follicles. In the thymus the immunostained cells were located in the medullary area and corresponded morphologically to mononuclear PAS-positive cells with histiocytic appearance. By contrast, in rat and human organs S-100 protein was detected in interdigitating reticulum cells and dendritic reticulum cells. The present findings indicate that S-100 protein is located differently in mouse lymphoid organs and in other mammalian dspecies.

Ki-M7 monoclonal antibody specific for myelomonocytic cell lineage and macrophages in human.

We describe a new monoclonal antibody, termed Ki-M7, which is specific to human myelomonocytic cell lineage and macrophages, as tested by immunohistochemical methods. Ki-M7 recognizes an intracytoplasmic antigen of molecular weight 29,000. Ultrastructurally, the antigen is localized in the lysosome and phagosome compartments and seems to be involved in generation of oxygen radicals during the respiratory burst. Dendritic cells, such as dendritic reticulum cells of lymphoid follicles and interdigitating reticulum cells of lymphoid T-zones, considered as accessory cells of the B- and T-cell immune response, respectively, do not show any reactivity with monoclonal antibody Ki-M7. Ki-M7 seems to be an appropriate reagent to clearly differentiate between the phagocytosing and the immune accessory population of the human monocyte/macrophage system.