Rapidly fatal leukemia comprising pleomorphic large granular lymphocytes: a report of 2 cases

Large granular lymphocytes (LGLs) are either cytotoxic T or natural killer (NK) cells exhibiting round nuclei and azurophilic cytoplasmic granules. Morphologically, neoplastic LGLs of T cell lineage (T-LGLLs) are usually indistinguishable from normal LGLs, while there is a wide morphological range of aggressive NK cell leukemia (ANKL).

We present 2 consecutive cases of leukemia comprising pleomorphic LGLs. One patient presented with drowsy consciousness and unstable hemodynamics. Her peripheral blood smear disclosed a significant number of LGLs with pleomorphic nuclei expressing CD2, CD56 and HLA-DR but not surface or cytoplasmic CD3 (cCD3). The second patient, previously healthy, presented with a sudden death. Her peripheral blood revealed LGLs ranging from round to pleomorphic nuclei with a CD2+ cCD3+ surface CD3- CD56+ phenotype and clonally rearranged T cell receptor gene. The findings of the first patient were consistent with ANKL and the second, T-LGLL. Both patients passed away shortly before treatment.

The 2 cases highlight the importance of a multidisciplinary approach in addition to cytological examination to reach accurate diagnoses of such rare leukemia cases.