Novel treatment of blastic plasmacytoid dendritic cell neoplasm: A case report

RATIONALE: Blastic plasmacytoid dendritic cell neoplasm (BPDCN), derived from precursors of plasmacytoid dendritic cells, is a rare and aggressive malignancy with frequent cutaneous involvement. Although cutaneous lesions are often chemosensitive, BPDCN portends a poor prognosis as most patients relapse after developing drug resistance. PATIENT CONCERNS: We report a case of a 65-year-old man who presented with a rapidly enlarging hyperpigmented plaque on his shoulder with subsequent similarly appearing macules and plaques on his chest, back, and neck. DIAGNOSIS: Skin biopsy revealed a dense adnexocentric dermal infiltrate of immature blastoid cells without epidermal involvement. The infiltrate was immunoreactive for CD4, CD56, CD123, and Bcl-2, but negative for CD3, CD8, CD30, MPO, EBER, and ISH. The patient was diagnosed with BPDCN based on these cell markers. INTERVENTION: Bone marrow biopsy and radiologic work-up showed no evidence of extracutaneous involvement. The patient attained partial remission after undergoing 2 rounds of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP regimen) before autologous stem cell transplantation, however, he quickly relapsed and developed new cutaneous lesions. OUTCOMES: The patient was treated with venetoclax, a Bcl-2 inhibitor, and exhibits complete resolution of prior skin findings and continues to remain free of new cutaneous lesions 10 months posttreatment initiation with venetoclax. LESSONS: Herein, we present a case that supports the use of venetoclax, a Bcl-2 inhibitor, in the off-label treatment of BPDCN with Bcl-2 overexpression. Only 1 prior case has reported the off-label use of venetoclax for the treatment of BPDCN. This case highlights a novel therapeutic option for BPDCN patients unresponsive to traditional treatment.