ALL-473 Dilemma of Diagnosing and Treating BPDCN; Case Report With Clinicopathological Correlation

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive hematological malignancy with a rare incidence with poor outcome. Usually, it presents by skin infiltration then dissemination and only 10% may present first by bone marrow (BM) infiltration. It has overlapping features with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) clinically and pathologically, and there are many diseases to be differentially diagnosed from them. There is no consensus for treating BPDCN, but there are some novel therapies that have emerged in the field for treating this group of patients. A case report of 47-year-old diabetic male, presented to the hematology unit of Oncology Center of Mansoura University with a large, elevated scalp mass on the anterior part near the forehead with overlying pressure necrosis of the skin and face edema and with similar lesions on the back. There were enlarged cervical and inguinal lymph nodes. Skin biopsy revealed infiltration by monomorphous medium-sized blastoid cells, with fine chromatin and scanty cytoplasm, pannicular extension, and no detected epidermotropism. Immunohistochemistry revealed diffuse membranous immunoreactivity for CD4, CD56, and BCL2. Ki-67 proliferation index was about 90%. CD117, MPO, CD34, CD20, CD5, CD3, ALK, CD79a, and CD30 showed negative immunoreactivity in the tumor cells. BM examination showed infiltration by 80% large blastoid cells with basophilic cytoplasm and fine chromatin. Multi-color-flowcytometry (MCF) revealed low CD45 expression (located in the blast pocket) and positive CD123, a spectrum of CD56 (moderate to negative), dim CD4, CD43, partial dim CD33, CD38, CD81, and partial CD36 (predominantly negative), and was negative for the rest of the panel. The patient received Hyper-CVAD protocol (cyclophosphamide, vincristine sulfate, doxorubicin hydrochloride, and dexamethasone) and skin lesions showed marvelous response after 1st cycle of chemotherapy. BM and FDG -PET/CT evaluation was free from abnormal cell infiltration. Now he is completing his chemotherapy and planned for allogenic stem cell transplantation (SCT). The diagnosis and management of such cases are challenging at all levels from the beginning of the disease, through the steps of diagnosis and finally in choosing the appropriate treatment protocol. We recommend ALL-based chemotherapy protocols especially Hyper-CVAD then allogenic SCT for better response and overall survival.