[2] While commonly presenting with these clinical features, BPDCN, particularly in its more advanced stages, may also involve malignant plasmacytoid dendritic cell infiltrations in and thereby injury to the liver, spleen, lymph nodes, central nervous system, or other tissues.
[5] Blastic plasmacytoid dendritic cell neoplasm typically responds to chemotherapy regimens used to treat hematological malignancies.
[5] Current translational research studies on treating BPDCN have therefore focused on non-chemotherapeutic regimens that target the molecular pathways which may promote the disease.
[6] Blastic plasmacytoid dendritic cell neoplasm occurs in children,[5] including neonates,[7] but is more common in adults, particularly those between the ages 60–80.
[5] BPDCN usually (i.e. 61%[5] to 90%[8] of cases) presents with skin lesions, i.e. nodules, tumors, red or purple papules, bruise-like patches, and/or ulcers that most often occur on the head, face, and upper torso.
[5] More advanced or severe cases may present with extreme organ and/or lymph node enlargements, skin lesions in virtually any site, and clinical evidence of malignant pDC infiltrations in the breasts, eyes, kidneys, lungs, gastrointestinal tract, bone, sinuses, ears, or testes.
They are distinguished from other dendritic, myeloid, lymphoid and NK cell types by exhibiting at least several of the following properties: 1) plasmacytoid morphology; 2) production of large amounts of type I interferons when properly stimulated; 3) ability to differentiate into conventional dendritic cells when properly stimulated; 4) the expression of key marker proteins such as granzyme B,[10] TCF4,[11] interleukin-3 receptor (i.e. CD123), CLEC4C, and Neuropilin,[9] and 5) failure to express certain marker proteins that are commonly expressed by myeloid, lymphoid, and NK cell lineages.
[4] Laboratory studies indicate that malignant pDC have a pathologically overactive NF-κB pathway that promotes their survival and production of various cytokines) that stimulate their own proliferation.
[12] BPDCN is suggested by a biopsy of skin lesions which reveals the infiltration by medium-sized blast (i.e. immature) cells into the dermis while sparing the epidermis.
All studies agree that pDC should have a typical plasmacytoid morphology and express a particular profile of marker proteins as detected by immunoassay and/or flow cytometry.
[8] A phase I clinical research study to test the safety and efficacy of a combination chemotherapy regimen consisting of methotrexate, L-asparaginase, idarubicin, and dexamethasone followed by allogenic or autologous bone marrow transplantation in 26 participants newly diagnosed with BPDCN is planned but not yet in its recruiting phase.
[15] Due to the high rates of recurrence following initial therapy and the short overall survival times of individuals with BPDCN, prognosis of the disease is poor.
Venetoclax inhibits the apoptosis-inhibiting action of BCL-2 and proved active in treating two patients with relapsed or refractory BPDCN.