Blastic plasmacytoid dendritic cell neoplasm developed on a patient with myeloproliferative neoplasm: A case report
Tzu-Yu Liu, Yu Yu
Department of Dermatology, Cathay General Hospital, Taipei, Taiwan
Correspondence Address:
Dr. Yu Yu
Department of Dermatology, Cathay General Hospital, No. 280, Sec. 4, Renai Road, Taipei 10630
Taiwan
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/ds.ds_16_22
Dear Editor,
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare but aggressive hematologic malignancy featuring unique “bruise-like” cutaneous lesions. Involvement of bone marrow, lymph nodes, or blood may also present. Prior history of other myeloproliferative disorders could be identified in some patients, indicating possible leukemic-transformation-like events of somewhat unknown pathogenesis.
A 67-year-old man with underlying BCR-ABL1 negative unclassifiable myeloproliferative neoplasm with leukocytosis (31.63 K/uL) and thrombocytosis (1073 K/uL) took hydroxyurea for 5 months. His disease was controlled well with normal leukocyte and platelet counts under hydroxyurea. However, he presented rapidly enlarging neck masses and “easy bruising” in the past 1 month. Physical examination revealed several purplish nonblanchable macules and patches on the scalp, chest, and upper back [Figure 1]a and [Figure 1]b. Multiple enlarged lymph nodes were also found at the neck [Figure 1]c. Blood tests showed leukocytosis (52.18 K/uL) with a proportion of blasts up to 74%, anemia (6.0 g/dL), and thrombocytopenia (45 K/uL). Biopsies of bone marrow and a neck lymph node both showed malignant hematopoietic neoplasm. The immunohistochemical stains showed positive for CD4, CD56, and CD123 [Figure 2]g, and negative for myeloperoxidase and Epstein–Barr virus-encoded small RNA (EBER) [Figure 2]f. Subsequent skin biopsy revealed dense infiltrate of monomorphic, poorly-differentiated, medium-sized tumor cells on histopathology investigation [Figure 2]a and [Figure 2]b. The immunohistochemical stains also showed identical results to previous biopsy [Figure 2]c, [Figure 2]d, [Figure 2]e. Differential diagnoses included CD56+ acute myeloid leukemia, nasal-type extranodal NK/T-cell lymphoma, cutaneous T-cell lymphoma, and BPDCN. According to the immunohistochemical stains, CD56+ acute myeloid leukemia and nasal-type extranodal NK/T-cell lymphoma were excluded due to negative results for myeloperoxidase and EBER. Positive results for CD4, CD56, and CD123 disclosed the diagnosis of BPDCN, which may present many superficial cutaneous lesions. He was then received treatment with cyclophosphamide, vincristine, doxorubicin, and dexamethasone. Regretfully, he was expired due to septic shock during the treatment.
Figure 1: Clinical presentation: (a) Bruise-like macules (violaceous macules) at the chest; (b) a purplish nodule at the right chest; (c) multiple palpable neck lymph nodes (white arrows).Figure 2: Histopathological investigation: (a) Histopathology stain of the skin biopsy revealed tumor cell infiltration to the dermis (H and E, ×100); (b) monomorphic, poorly-differentiated, medium-sized tumor cells (H and E, ×400); immunohistochemical stain of skin biopsy revealed (c) positive for CD4 (×100), (d) positive for CD56 (×100), and (e) negative for myeloperoxidase (×100); (f) immunohistochemical stain of neck lymph node biopsy revealed negative for EBER (×200), but (g) positive for CD123 (×200).BPDCN arises from the precursors of myeloid-derived resting plasmacytoid dendritic cells. Clinical manifestations include cutaneous lesions (~90%), involvement of bone marrow, blood, lymph nodes, and central nervous system involvement (~30%).[1],[2] The skin lesions may present as isolated purplish nodules, bruise-like patches, or disseminated purplish plaques.[3] The different skin presentation is not currently a significant prognostic factor. For patients diagnosed with BPDCN, about 10%–20% of patients have prior or concomitant hematologic malignancies. These hematologic malignancies include myelodysplastic syndrome, chronic myelomonocytic leukemia, myelofibrosis, and myeloma. Previous research showed a trend for shorter complete remission 1 in patients with prior or concomitant hematologic malignancies, but with no significant difference for overall survival.[4],[5]
The treatment for the newly diagnosed patients is induction chemotherapy with an acute lymphoblastic leukemia-like regimen that includes the central nervous system prophylaxis or therapy. If the patient achieved complete remission, allogeneic hematopoietic cell transplantation was suggested.[6] New therapeutic approaches were developed recently. Tagraxofusp, a CD123-directed cytotoxin consisting of human interleukin-3 fused to truncated diphtheria toxin, showed clinical response to untreated or relapsed BPDCN. Venetoclax, a B-cell lymphoma-2 (BCL-2) inhibitor, also showed response due to BCL-2 dependence of BPDCN.[7],[8]
BPDCN is a hematologic malignancy mostly manifested as cutaneous lesions. In addition to chemotherapy, new treatment options as targeted therapies were developed recently. In patients with myeloproliferative disorders who develop bruise-like skin lesions, we should take BPDCN into the differential diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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