Body cavity-based presentation of natural killer cell lymphoma.

We describe an unusual case of a 31-year-old Mexican woman who presented with pleural and peritoneal effusions involved by Epstein-Barr virus-positive non-Hodgkin's lymphoma of natural killer (NK)-cell lineage. The patient had no symptoms that could be related to her nasal region, and physical examination and radiologic studies showed no evidence of lymphadenopathy, organomegaly, or other extranodal masses. Thus, this case clinically mimicked body cavity-based lymphoma. Extranodal NK/T-cell lymphoma of nasal type is the current designation for these neoplasms in the recently proposed World Health Organization classification of lymphoid neoplasms. These tumors previously have been referred to many other names, including lethal midline granuloma, midline malignant reticulosis, polymorphic reticulosis, angiocentric immunoproliferative lesion, and angiocentric lymphoma. Nasal-type NK/T-cell lymphomas typically involve the nasal region, but may involve other extranodal sites, such as skin and gastrointestinal tract. The malignant cytologic features and the presence of azurophilic granules within the cell cytoplasm observed in Wright-Giemsa-stained cytocentrifuge preparations led to immunophenotypic and molecular genetic studies that were essential in establishing the correct diagnosis. As demonstrated in the case reported, extranodal NK/T-cell lymphomas of nasal-type can be clinically aggressive and may be associated with paraneoplastic phenomena.