Primary bone marrow natural killer/T-cell lymphoma/leukemia: a report of the two cases

Abstract

Natural killer (NK) cell neoplasms are aggressive tumors and comprise aggressive NK cell leukemia (ANKL) and extranodal nature killer (NK)/T-cell lymphoma (ENKTL), nasal type. Here we report two cases of NK cell neoplasm localized in the bone marrow without peripheral blood involvement. Both patients presented with prolonged fever, anemia, and thrombocytopenia and were treated initially as infectious disease. Imaging studies revealed splenomegaly without any nodular lesion or lymphadenopathy. Bone marrow examination revealed extensive marrow involvement in both cases. Serum EBV viral loads at diagnosis of these two patients were at 130,000 and 60,000 copies/μL, respectively. Staging workup including nasal examination/biopsy was negative. Both patients passed away in a month. These tumors were diag-nostically challenging due to the unusual clinical presentation and absence of leukemic change, tumor mass or lymphadenopathy. Our cases demonstrate that lymphoma/leukemia should be considered in patients with fever of unknown origin and marrow aspiration/biopsy be performed. Early diagnosis and novel effective therapeutic regimens may benefit these patients. This case may be considered as ANKL in the aleukemic phase or ENKTL with marrow involvement/presentation. A diagnostic labeling of either ANKL or ENKTL might be arbitrary and only of personal preference, although molecular study might help with the differential diagnosis.