浆细胞样树突状细胞肿瘤是起源于浆细胞样树突状细胞（pDC）的罕见肿瘤。它们分为两种类型：母细胞性浆细胞样树突状细胞肿瘤和成熟浆细胞样树突状细胞增殖。还发现 pDC 的肿瘤性扩张与骨髓瘤形成有关。我们介绍了一名 62 岁女性的诊断具有挑战性的病例，她因面部和肘部附近的伸肌表面出现大量出血性结节和丘疹以及中性粒细胞减少性发热而到急诊科就诊。该患者有明显的红斑狼疮病史，并且最近进行了涉及“浆细胞样树突状细胞增殖”的淋巴结切除活检。进行了打孔活检，结果显示非典型中等大小的单核细胞强烈的真皮浸润。浸润液 CD4、CD43 和 CD123 呈阳性。 CD3 和 CD8 突出显示背景 T 细胞。浸润液 CD10、CD34、CD56、CD68、CD117、髓过氧化物酶、溶菌酶、TdT 和 TCL-1 呈阴性。这些发现有利于浆细胞样树突状细胞增殖累及皮肤的诊断。鉴于与急性白血病的关联，建议随后进行骨髓活检。进行了骨髓活检，结果显示原始细胞增加（500 个差异细胞计数为 68%）。此外，还进行了免疫组织化学染色，结果显示母细胞 CD34 和 BEST（α-萘基丁酸酯酶）细胞化学染色呈阳性。该诊断与急性粒单核细胞白血病的骨髓受累一致。鉴于 pDC 肿瘤和髓系肿瘤的重叠症状（皮肤病变、腺病、骨髓受累）以及同时出现的可能性，提高认识对于帮助防止潜在的误诊、漏诊和及时调查可能的相关肿瘤至关重要。版权所有 © 2024 Wolters Kluwer Health, Inc. 保留所有权利。

Plasmacytoid dendritic cell neoplasms are rare neoplasms originating from plasmacytoid dendritic cells (pDCs). They are subclassified into 2 types: blastic plasmacytoid dendritic cell neoplasm and mature plasmacytoid dendritic cell proliferation. Neoplastic expansion of pDCs has also been found to be associated with myeloid neoplasia. We present the diagnostically challenging case of a 62-year-old woman who presented to the emergency department with numerous hemorrhagic nodules and papules on the face and extensor surfaces near the elbows and neutropenic fevers. The patient had a history notable for lupus erythematosus and a recently performed excisional lymph node biopsy involved by a "plasmacytoid dendritic cell proliferation." A punch biopsy was performed, which showed a robust dermal infiltrate of atypical intermediate-sized mononuclear cells. The infiltrate was positive for CD4, CD43, and CD123. CD3 and CD8 highlighted background T cells. The infiltrate was negative for CD10, CD34, CD56, CD68, CD117, myeloperoxidase, lysozyme, TdT, and TCL-1. The findings favored a diagnosis of cutaneous involvement of the plasmacytoid dendritic cell proliferation. Given the association with acute leukemias, a subsequent bone marrow biopsy was recommended. The bone marrow biopsy was performed, which showed increased blasts (68% on a 500 differential cell count). Furthermore, immunohistochemical stains were performed, which highlighted the blasts to be positive for CD34 and BEST (alpha-naphthyl butyrate esterase) cytochemical stain. This diagnosis was consistent with bone marrow involvement of acute myelomonocytic leukemia. Given the overlapping presenting symptoms (skin lesions, adenopathy, marrow involvement) of pDC neoplasms and myeloid neoplasia and the possibility of presenting concurrently, increased awareness is of pivotal importance to help prevent potential misdiagnosis, missed diagnosis, and prompt investigation of possible associated neoplasms.Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.