Blastic plasmacytoid dendritic cell neoplasia - a rare type of acute leukemia

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), recently classified among the acute myeloid leukemia and related precursor neoplasms, is a rare hematological malignancy with highly aggressive clinical course. We report a case of a 55 year-old female patient who presented spontaneous rupture of the spleen. The histopathological diagnosis without immunohistochemistry was splenic marginal zone non-Hodgkin lymphoma (NHL). The patient received 4 courses of polychemotherapy. Due to the unfavorable evolution the spleen was histopathologically reexamined and immunohistochemistry was performed in another laboratory. The diagnosis of NHL was excluded. Undifferentiated malignant cell proliferation, possible myeloid was suspected. Due to the discrepancy between diagnoses, a third immunohistological examination was performed in a third laboratory. NHL was excluded and myeloid, NK-cell or plasmacytoid dendritic cell leukemia was suspected. The patient was admitted to our clinic after 8 months from the initial diagnosis. Immunophenotyping by flowcytometry from the bone marrow showed 23% blasts positive for CD4, CD56, CD123, HLA-DR, CD38, CD11b, CD2, and negative for lineage specific markers of B-, T-lymphoid, NK- or myelomonocytic cells. The final diagnosis was BPDCN in leukemic phase. Due to the diversity of the clinical presentation, morphology and immunophenotype of BPDCN the diagnosis of this rare malignancy remains challenging. Immunophenotyping by flowcytometry is superior to immunohistochemistry because of the availability of a larger panel of antibodies and the possibility to identify the intensity of antigen expression. The atypical forms of BPDCN should be recognized early in order to manage properly the patients with this aggressive disease