Primary cutaneous blastic plasmacytoid dendritic cell neoplasm without extracutaneous manifestation: case report and review of the literature.

Blastic plasmacytoid dendritic cell (BPDC) neoplasm is a rare, highly aggressive hematopoietic malignancy with involvement of bone marrow and peripheral blood. We present 2 cases of primary cutaneous BPDC neoplasm without extracutaneous manifestation during the course of disease. A 36-year-old and a 51-year-old male presented with erythematous patches, purple plaques, and nodules on the head, trunk, and extremities. Skin biopsies revealed that the lesions of both cases were composed of diffusely medium-sized monomorphic blastoid cells infiltrating into the dermis and subcutis. The neoplastic cells were strongly positive for CD4, CD56, CD123, and TdT, whereas other T-cell markers and EBV markers were not expressed. The patients underwent polychemotherapy with hyper-CVAD regimen and obtained a remarkable clinical response with regression of skin lesions. No sign of recurrence and extracutaneous manifestation was found during the period of follow-up. We presume that the favorable prognosis of our cases might result from the presentation only with a skin lesion, diffuse TdT expression in tumor cells, and aggressive chemotherapy with hyper-CVAD regimens. Laboratory examination for blood and bone marrow should be performed every 3-6 months during the first period of follow-up to monitor the progression of disease even if the patients had complete remission at initial chemotherapy.