A case of blastic plasmacytoid dendritic cell neoplasm: Cytomorphological findings of the touch imprint specimen of lymph node

The patient is a 75‐year‐old man with axillary lymphadenopathy presenting an indurated papule on his buttock. Touch imprint cytology of the biopsied axillary lymph node revealed the monotonous appearance of medium‐sized tumor cells. The nuclei had a slightly irregular contour, finely dispersed chromatin, and a conspicuous nucleolus. Some tumor cells had intracytoplasmic microvacuoles. Immunohistochemistry of the imprint specimens showed that the tumor cells were positive for CD56 and CD123. Histological diagnosis of the lesion was blastic plasmacytoid dendritic cell neoplasm (BPDCN). Epstein‐Barr virus‐encoded RNAs were not detected in the tumor cells. Neither immunoglobulin heavy chain genes nor T‐ cell receptor genes was clonally rearranged. BPDCN should be strongly considered during the differential diagnosis of CD56‐positive neoplasms of the skin. We demonstrated a possible contribution of the cytomorphological and immunohistochemical findings of the touch imprint specimens to the diagnosis of BPDCN. Diagn. Cytopathol. 2013. © 2012 Wiley Periodicals, Inc.