Jabbour Mark N, Fedda Faysal A, Tawil Ayman N, Shabb Nina S, Boulos Fouad I
Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon.
Appl Immunohistochem Mol Morphol. 2014 Oct;22(9):705-12. doi: 10.1097/PAI.0b013e318224a5ce.
Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm of follicular dendritic cells, most commonly affecting the lymph nodes and extranodal soft tissues of the head and neck, but also potentially arising in any visceral organ. FDCS with its diverse morphologies raises an occasionally challenging differential of primary and metastatic tumors with overlapping histologic and immunohistochemical features. When involving the head and neck, FDCS may be confused with squamous cell carcinoma, undifferentiated carcinoma, extracranial meningioma, and variants of papillary thyroid carcinoma. We describe here a case of FDCS showing nuclear grooves, intranuclear pseudoinclusions, diffuse epithelial membrane antigen and focal cytokeratin staining, and the first documented report of positivity for thyroid transcription factor-1. A discussion of the differential diagnosis and potential diagnostic pitfalls in FDCS brought forth by thyroid transcription factor-1 immunoreactivity and a full review of clinicopathologic and immunohistochemical features of head and neck FDCS are presented.
滤泡性树突状细胞肉瘤（FDCS）是一种罕见的滤泡性树突状细胞肿瘤，最常累及头颈部的淋巴结和结外软组织，但也可能发生于任何内脏器官。FDCS形态多样，在鉴别具有重叠组织学和免疫组化特征的原发性和转移性肿瘤时偶尔会带来挑战。当累及头颈部时，FDCS可能会与鳞状细胞癌、未分化癌、颅外脑膜瘤和甲状腺乳头状癌的变体相混淆。我们在此描述一例显示核沟、核内假包涵体、弥漫性上皮膜抗原和局灶性细胞角蛋白染色的FDCS病例，以及甲状腺转录因子-1阳性的首例文献报道。本文还讨论了由甲状腺转录因子-1免疫反应性引发的FDCS鉴别诊断及潜在诊断陷阱，并对头颈部FDCS的临床病理和免疫组化特征进行了全面综述。
