JC EH lin xp ematopathol Original article INTRODUCTIONBlastic plasmacytoid dendritic cell neoplasm (BPDCN) is a relatively rare hematological malignancy, 1 accounting for 0.44% of all hematological malignancies and 0.7% of all cutaneous lymphomas.2 BPDCN is a clinically aggressive tumor derived from the precursors of plasmacytoid dendritic cells (pDC).1 It usually occurs at the age of 50-70 and is rare in pediatric patients; the ratio of male to female patients is 2.5-2.7:1, and the median survival is 12-14 months. 1-4The clinical features and evolution of BPDCN are rather homogenous and categorized into dermatopathic (>90% of cases) and leukemic patterns. 5 The dermatopathic pattern is characterized by a deceptive indolent onset dominated by skin lesions, which is the prominent and only detectable clinical feature in nearly 50% of patients, followed by tumor dissemination. Conversely, the leukemic variant is characterized by an elevated white blood cell count, circulating neoplastic cells, and massive bone marrow (BM) infiltration. Pure leukemic presentation is very rare (7% of 756 cases) and is mostly associated with multiple skin lesions. Other manifestations are related with tumor infiltration into the lymph nodes (localized and generalized lymphadenopathy), spleen, and liver. Notably, BPDCN can be precisely diagnosed by the immunohistochemical scoring system using CD4, CD56, and Blastic plasmacytoid dendritic cell (pDC) neoplasm (BPDCN) is a relatively rare hematological malignancy with significantly complex clinicopathological features that are still unclear. This study aimed to analyze the clinicopathological data of BPDCN and evaluate immunohistochemical detection of minimal bone marrow (BM) involvement. In this study, we examined skin and BM lesions from 6 patients with BPDCN. Neoplastic cells tested positive for CD303 (polyclonal, 100%; monoclonal, 40%) in the skin lesions and for CD303 (polyclonal, 100%; monoclonal, 67%) in the BM clots. Although immunostaining of CD4, CD56, CD123, CD303, and TCLl detected minimal BM involvement in 3 patients, morphological identification was challenging in the BM clots stained with hematoxylin-eosin. In conclusion, our results demonstrate the significance of observing BM smears to detect neoplastic cells and that immunohistochemical examination, including CD303 antibodies, is useful to detect minimal BM involvement. This study is the first to report the expression of thymic stromal lymphopoietin (TSLP) and its receptor in BPDCN cells. Therefore, the TSLP/TSLP receptor axis may be associated with the proliferation of BPDCN, and consequently, the survival of patients.

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+)ALL) is one of the highest-risk ALL groups. Whenever possible, patients with Ph(+)ALL should undergo allogeneic hematopoietic stem cell transplantation (HSCT) after induction of remission. Although unrelated cord blood transplantation (CBT) has become a common treatment in adult patients who lack a sibling donor, data on the efficacy of CBT for Ph(+)ALL are limited. We analyzed the clinical outcomes of 20 Ph(+)ALL patients who underwent CBT (n = 8) or unrelated bone marrow transplantation (BMT) (n = 12). The median age was 41 years (range, 17-55 years). All but one of the patients were treated with an imatinib-based regimen before HSCT, and 19 patients were in first complete remission (CR) and 1 patient was in second CR at the time of HSCT. Seventeen patients received a myeloablative conditioning regimen containing 12 Gy of total-body irradiation, and 3 received a reduced-intensity conditioning regimen. After a median of 26 months of follow-up, estimated 3-year overall and leukemia-free survival rates were 100% and 85%, respectively, after CBT, and 49% and 38%, respectively, after unrelated BMT. The CBT group had significantly better overall survival than the BMT group (P = .02). Although BCR-ABL transcript was detected in 4 of 8 CBT patients at transplantation, 7 patients remained in molecular CR. Our findings suggest that CBT may be a viable option as postinduction therapy for Ph(+)ALL in patients lacking a sibling donor.

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A 16-year-old boy, who had been initially examined for bilateral blepharedema and slight eruption, presented with rapidly deteriorating symptoms in associating with headache and consciousness disturbance. He was diagnosed to have primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (PCAE-CTL) by a biopsy of the skin and brain. After whole-brain radiation and some courses of chemotherapy, cord blood transplantation was performed with myeloablative conditioning. After transplantation, the cerebral dysfunction gradually improved. Disease remission was confirmed by the disappearance of any abnormal findings on electroencephalogram and magnetic resonance imaging. PCAE-CTL is reported to be an extremely aggressive disease with a poor prognosis, but the timely performance of cord blood transplantation is considered to be a promising treatment strategy.

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia accompanied by an aggressive clinical course and dismal prognosis. We herein report a case of AMKL preceded by mediastinal germ cell tumor that relapsed early after allogeneic hematopoietic stem cell transplantation with myeloablative conditioning but was successfully treated using salvage cord blood transplantation (CBT) with reduced-intensity conditioning. Although several serious complications developed, sustained remission with a favorable general condition was ultimately achieved. Although an optimal therapeutic strategy remains to be established, the graft-versus-leukemia effect of CBT may be promising, even for the treatment of refractory AMKL.