Moon Matthew J, Milhem Mohammed M, Rieth John M
Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
Department of Internal Medicine, Division of Hematology, Oncology and Blood and Marrow Transplantation, University of Iowa, Iowa City, IA, USA.
Case Rep Oncol. 2025 Jul 3;18(1):1050-1056. doi: 10.1159/000546447. eCollection 2025 Jan-Dec.
Histiocytic sarcoma (HS) and interdigitating dendritic cell sarcoma (IDCS) are both extremely rare and aggressive histiocytic neoplasms that are most often treated with lymphoma-based chemotherapy; however, there is growing use of immune checkpoint inhibitors (ICI) in the second- or further-line settings as prognosis is typically poor in these neoplasms.
We describe two cases: first, HS in a 60-year-old man with primary tumor in the right anterior lower limb, and second, IDCS in an 82-year-old man in the right para-parotid region after initial wide local excision of a right postauricular mass suggestive of a pleomorphic undifferentiated sarcoma. Systemic imaging showed retroperitoneal, inguinal, and pelvic adenopathy in the first case and no distant metastases in the second case. Both were diagnosed via biopsy with extensive immunohistochemistry and were also found to be strongly positive on PDL1 testing. Treatment was initiated with ICIs in both patients, which was paired with palliative radiotherapy for the HS patient. Both cases exhibited a durable response to treatment upon repeated systemic imaging.
To our knowledge, these are the first-reported cases of the use of ICIs in the first-line setting in these histiocytic neoplasms and highlight their efficacy. The significant elevation in PDL1 expression seen in both cases may serve as a potential biomarker of excellent response in these neoplasms.
组织细胞肉瘤（HS）和交错突细胞肉瘤（IDCS）均为极其罕见且侵袭性强的组织细胞肿瘤，通常采用基于淋巴瘤的化疗进行治疗；然而，由于这些肿瘤的预后通常较差，免疫检查点抑制剂（ICI）在二线或后续治疗中的应用越来越多。
我们描述了两例病例：第一例是一名60岁男性，右下肢前下部有原发性肿瘤，诊断为HS；第二例是一名82岁男性，右侧耳后肿块最初被提示为多形性未分化肉瘤，在进行广泛局部切除后，右腮腺旁区域诊断为IDCS。全身影像学检查显示，第一例患者有腹膜后、腹股沟和盆腔淋巴结肿大，第二例患者无远处转移。两例均通过活检及广泛免疫组化确诊，且PDL1检测均呈强阳性。两名患者均开始使用ICI治疗，HS患者同时接受了姑息性放疗。经反复全身影像学检查，两例患者对治疗均表现出持久反应。
据我们所知，这些是首次报道的在这些组织细胞肿瘤一线治疗中使用ICI的病例，并突出了其疗效。两例患者中观察到的PDL1表达显著升高可能是这些肿瘤对治疗反应良好的潜在生物标志物。
