[Blastic plasmacytoid dendritic cell neoplasm: A clinico-pathological retrospective analysis of thirteen cases]

To investigate the clinicopathological features of blastic plasmacytoid dendritic cell neoplasm (BPDCN).

A total of 13 cases of BPDCN diagnosed in Peking University First Hospital from January 2013 to March 2022 were collected. The clinical features, histopathological characteristics, immunophenotypes and prognosis of the patients were analyzed retrospectively, and the related literatures was reviewed as well.

Among the 13 patients, 11 were male and 2 were female, with a median age of 62 years (ranging from 5 to 78 years). Among them, single organ involvement occurred in 5 cases, all of which presented with skin lesions. Two or more organs were involved in other 8 cases (single organ with bone marrow involved in 3 cases; skin, bone marrow and lymph node involved simultaneously in 3 cases; skin, bone marrow, lymph node and spleen involved simultaneously in 2 cases). Histopathologically, it was characterized by the proliferation of medium to large atypical blastic cells, which infiltrated the whole thickness of dermis. When involved, the bone marrow lesions mainly appeared in a diffuse pattern, while the lymph node structure was usually destroyed, and the red pulp of the affected spleen was diffusely invaded. Immunohistochemical staining showed that all the 13 cases were positive for CD4, CD56, and CD123 (13/13) in varying degrees. All the 9 cases expressed TCL1 (9/9). Variable expression of CD68 (KP1) (8/13), TdT (7/12), CD117 (2/6), and high Ki-67 proliferation index (40%~80%) were showed. The neoplastic cells lacked expressions of CD20, CD3, MPO, CD34, or CD30; EBER in situ hybridization were negative (0/9). After definite diagnosis, 6 cases received chemotherapy, among which 1 received adjuvant radiotherapy, and 2 received subsequent bone marrow transplantation. Another 2 cases only received maintenance treatment. The median follow-up time was 14 months (ranging from 6 to 36 months), 5 patients died of the disease (6 to 18 months), 3 patients survived (7 to 36 months up to now), and the remaining 5 patients lost follow-up.

BPDCN is a rare type of malignant lymphohematopoietic tumor with aggressive behavior and poor prognosis. The diagnosis should be made combining clinical features, histopathology, and immunohistochemical phenotype. Attention should be paid to differentiating BPDCN from other neoplasms with blastoid morphology or CD4+CD56+ tumors.