A 19-year-old female presented with a dark erythematous maculopapule measuring 2 cm in diameter on the left lower limb for more than one year.Physical examination revealed an enlarged cherry-like lymph node in the right inguinal region.Histopathology of the lesion revealed that the normal structure of skin disappeared absolutely,and there was a diffuse infiltrate of medium-sized lymphoid tumor cells with unclear nucleoli.Immunohistochemically,the tumor cells strongly expressed CD4,CD56 and CD123,and partially expressed terminal deoxynucleotidyl transferase (TdT).Flow cytometric analysis of bone marrow aspirates showed that abnormal cells amounted to 59.9％,and were positive for CD123st (strong),human leucocyte antigen-DRst (strong),CD56,CD304 (blood dendritic cell antigen-4),CD7,CD11b,CD33,CD36 and chemokine (C-X-C motif) receptor 4,CD13 (dim),CD4 (partial) and CD117 (partial).Transmission electron microscopy of bone marrow cells revealed that there were massive uniformly sized lymphoid cells with thick processes on cell surfaces,a high nucleus/cytoplasm ratio,centrally located round nuclei occasionally with deep gyrus-like notches,clumped marginated heterochromatin and multiple nucleoli.Moreover,a small amount of cytoplasm was observed in the lymphoid cells with the presence of mitochondria and endoplasmic reticulum arranged in concentric circles,which were characteristic of plasma cells.The features of both dendritic cells and plasma cells were found in the tumor cells through transmission electron microscopy.Based on the above findings,a diagnosis of blastic plasmacytoid dendritic cell neoplasm (BPDCN) was made.

BACKGROUND:As tissue engineering brings new hope to the worldwide problem of articular cartilage repair,the construction of light-curing 3D printed hydrogel scaffolds with biomimetic composition is of great significance for cartilage tissue engineering. OBJECTIVE:To construct a biomimetic methacryloylated hyaluronic acid/acellular Wharton's jelly composite hydrogel scaffold by digital light processing 3D printing technology,and to evaluate its biocompatibility. METHODS:Wharton's jelly was isolated and extracted from human umbilical cord,then decellulated,freeze-dried,ground into powder,and dissolved in PBS to prepare 50 g/L acellular Wharton's jelly solution.Methylallylated hyaluronic acid was prepared,lyophilized and dissolved in PBS to prepare 50 g/L methylallylated hyaluronic acid solution.Acellular Wharton's jelly solution was mixed with methacrylyacylated hyaluronic acid solution at a volume ratio of 1:1,and was used as bio-ink after adding photoinitiator.Methylacrylylated hyaluronic acid hydrogel scaffolds(labeled as HAMA hydrogel scaffolds)and methylacrylylated hyaluronic acid/acellular Wharton's jelly gel scaffolds(labeled as HAMA/WJ hydrogel scaffolds)were prepared by digital light processing 3D printing technology,and the microstructure,swelling performance,biocompatibility,and cartilage differentiation performance of the scaffolds were characterized. RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the two groups of scaffolds showed a three-dimensional network structure,and the fiber connection of HAMA/WJ hydrogel scaffold was more uniform.Both groups achieved swelling equilibrium within 10 hours,and the equilibrium swelling ratio of HAMA/WJ hydrogel scaffold was lower than that of HAMA hydrogel scaffold(P＜0.05).(2)CCK-8 assay showed that HAMA/WJ hydrogel scaffold could promote the proliferation of bone marrow mesenchymal stem cells compared with HAMA hydrogel scaffold.Dead/live staining showed that bone marrow mesenchymal stem cells grew well on the two groups of scaffolds,and the cells on the HAMA/WJ hydrogel scaffolds were evenly distributed and more cells were found.Phalloidine staining showed better adhesion and spread of bone marrow mesenchymal stem cells in HAMA/WJ hydrogel scaffold than in HAMA.(3)Bone marrow mesenchymal stem cells were inoculated into the two groups for chondrogenic induction culture.The results of qRT-PCR showed that the mRNA expressions of agglutinoglycan,SOX9 and type Ⅱ collagen in the HAMA/WJ hydrogel scaffold group were higher than those in the HAMA hydrogel scaffold group(P＜0.05,P＜0.01).(4)These findings indicate that the digital light processing 3D bioprinting HAMA/WJ hydrogel scaffold can promote the proliferation,adhesion,and chondrogenic differentiation of bone marrow mesenchymal stem cells.