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[Sustained remission of blastic plasmacytoid dendritic cell neoplasm with ABVD chemotherapy].

Blastic plasmacytoid dendritic cell neoplasm is a rare but clinically aggressive tumor known to be derived from the precursors of plasmacytoid dendritic cells with frequent cutaneous involvement. Though the majority of patients initially respond to multi-agent chemotherapy, most cases without hemopoietic stem cell transplantation relapse within a year. We describe a case of a 71-year-old man with a dark-purple subcutaneous nodule (5×3 cm) under his right auricle. Histologic examination of the excisional biopsy specimen revealed a diffuse proliferation of blast cells with irregular nuclei, fine chromatin and one to several small nucleoli in the dermis extending to the subcutaneous soft tissues. The tumor cells expressed CD123, CD56, CD4, CD7, LCA, and TdT but not CD3, CD20, CD79a, CD10, CD68, CD163, myeloperoxidase (MPO), or naphthol-ASD-chloroacetate (ASD-Ch) esterase. A diagnosis of blastic plasmacytoid dendritic cell neoplasm was made. He did not have any other lesions except for the solitary skin nodule. He had refractory cytopenia with multilineage dysplasia (RCMD) and renal dysfunction. It was difficult for him to receive hemopoietic stem cell transplantation because of his advanced age and renal dysfunction. We had previously experienced successful treatment with ABVD chemotherapy for interdigitating dendritic cell sarcoma after ineffective CHOP chemotherapy. The plasmacytoid dendritic cell is one of the precursor cells of the interdigitating dendritic cell. Therefore we tried to apply ABVD therapy to him. The first course of ABVD induced complete remission. Although the therapies were reduced and postponed because of various complications, he is now in complete remission that has lasted for 21 months. Although previously not reported, ABVD therapy is useful for patients with blastic plasmacytoid dendritic cell neoplasm who cannot receive hemopoietic stem cell transplantation.