Hupp Meghan, Najmuddin Mufaddal, Dincer Huseyin Erhan, Mallery James Shawn, Amin Khalid, Stewart Jimmie
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota.
Department of Pulmonary, Critical Care and Sleep Medicine, University of Minnesota, Minneapolis, Minnesota.
Diagn Cytopathol. 2019 Aug;47(8):821-827. doi: 10.1002/dc.24192. Epub 2019 Apr 24.
Solitary fibrous tumor (SFT) is an uncommon fibroblastic neoplasm with considerable risk of local recurrence. SFT is histologically characterized by bland spindled-to-epithelioid cells in alternating hyper- and hypocellular zones, a "patternless pattern," ectatic "staghorn" vessels with variable edematous perivascular stroma, and thick ropey collagen. Cytologically, smears are variably cellular with spindled-to-epithelioid cells with oval nuclei, wispy cytoplasm, multiple inconspicuous nucleoli, and occasional nuclear pseudoinclusions. Small vessels and bare/stripped nuclei are generally present while mild atypia is not uncommon. STAT6 nuclear expression is the most useful immunohistochemical stain and is the product of a NAB2-STAT6 gene fusion. SFTs with mediastinal involvement may be diagnostically challenging due to proximity to vital structures and anticipated patient risks. Endobronchial and endoscopic ultrasound-guided fine-needle aspiration (EBUS/EUS-FNA) are minimally-invasive tissue sampling methods that provide diagnostic material while minimizing patient risk, and the mediastinum is accessible by both procedures. Small aspirate samples and SFT nonspecific features can compound the diagnostic difficulty, although familiarity with the cytologic, morphologic, immunophenotypic, and genetic features of SFTs assist the pathologist in confirming the diagnosis. Pathologists must also be aware of high-risk SFT features to ensure appropriate therapy and management. Case #1 describes a recurrent mediastinal SFT with high-risk features sampled by EUS-FNA. Case #2 describes a primary diagnosis of mediastinal SFT with malignant behavior made on an EBUS-FNA specimen.
孤立性纤维瘤（SFT）是一种罕见的成纤维细胞肿瘤，具有较高的局部复发风险。SFT的组织学特征为：在细胞丰富区和细胞稀少区交替出现的温和梭形至上皮样细胞，呈“无模式的模式”，扩张的“鹿角状”血管伴有不同程度的血管周围水肿性间质，以及粗大的绳索状胶原纤维。在细胞学上，涂片细胞量不一，有梭形至上皮样细胞，核呈椭圆形，胞质纤细，有多个不明显的核仁，偶尔可见核假包涵体。通常可见小血管和裸核/核仁裸露，轻度异型性并不少见。STAT6核表达是最有用的免疫组化染色，是NAB2 - STAT6基因融合的产物。由于靠近重要结构以及预期的患者风险，累及纵隔的SFT在诊断上可能具有挑战性。支气管内和内镜超声引导下细针穿刺活检（EBUS/EUS - FNA）是微创组织采样方法，可提供诊断材料，同时将患者风险降至最低，并且两种方法均可到达纵隔。尽管熟悉SFT的细胞学、形态学、免疫表型和遗传学特征有助于病理学家确诊，但小的穿刺样本和SFT的非特异性特征会增加诊断难度。病理学家还必须了解SFT的高危特征，以确保进行适当的治疗和管理。病例1描述了通过EUS - FNA采样的具有高危特征的复发性纵隔SFT。病例2描述了根据EBUS - FNA标本做出的具有恶性行为的纵隔SFT的初步诊断。
