Low-Grade Lymphomas in the Background of Numerous Multinucleated Histiocytic Giant Cells Can Be Missed

Epithelioid granulomas, epithelioid histiocytes, and occasional multinucleated giant cells are recognizable pathologic findings in lymphomas, particularly in Hodgkin lymphomas. The giant cells could be neoplastic and nonneoplastic. The nonneoplastic giant cells are of different histogenesis. They include, in the majority of cases, histiocytes. Usually, they are minor easily recognizable components of the nodal lymphomas. To our knowledge, low-grade B-cell non-Hodgkin lymphomas with numerous multinucleated histiocytic giant cells without epithelioid granulomas or crystals formation have not been previously reported. This might present a diagnostic challenge for the unwary pathologists since the diagnostic workout will be focused on the giant cells that might mask the apparently mixed bland-looking neoplastic lymphocytic background. We report a case of a 24-year-old woman who presented with generalized lymphadenopathy, organomegaly, and B-symptoms. The lymph nodes were enlarged and diffusely effaced with a striking feature of numerous multinucleated giant cells with a background of apparently mixed population of small lymphocytes and plasma cells. Initially, the diagnosis of a small low-grade lymphoma was histologically missed and the focus was on the differential diagnoses of the giant cells. Immunohistochemistry and flow cytometry raised the suspicion of masked small lymphocytic lymphoma that was subsequently confirmed by molecular studies. The rarity of small lymphocytic lymphoma and the unusual histologic features in this case confounded the clinical and pathologic diagnosis.