Department of Pathology, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, China.
Department of Pathology, The Fifth Division Hospital of Xinjiang Production and Construction Corps, Xinjiang Uygur Autonomous Region, Bole, 833400, China.
Diagn Pathol. 2024 Oct 25;19(1):140. doi: 10.1186/s13000-024-01564-4.
Solitary fibroous tumors (SFTs) are distinctive soft tissue tumors characterized by rearrangements of NAB2-STAT6 gene, which are associated with thin-walled, branching, "staghorn"-shaped vessels. SFTs are originally classified as a type of hemangiopericytoma (HPC). Classical SFTs are composed of spindle to ovoid cells arranged haphazardly or in fascicles. Rarely, SFTs exhibit unusual morphological variants such as fat formation, giant cells, dedifferentiation, or epithelioid variant. The epithelioid cell variant, which is composed almost entirely of epithelioid cells and arranged in solid or nest patterns, is extremely rare and frequently malignant.
In this study, we reported three cases of epithelioid SFTs (ESFTs) located in extrathoracic sites (right lateral ventricle, right lumbar, left pelvis). All the subjects in this study were elderly, with a predominance of female patients, accounting for two out of the three cases, and only one case involved a male patient. The tumor cells were entirely composed of epithelioid cells and exhibited positive for CD34 and STAT-6 markers. Ultimately, the majority of cases (two out of three) were diagnosed as malignant SFTs.
This study aims to enhance the awareness of ESFTs. In these cases, irrespective of the onset location, the arrangement patterns of tumor cells, such as papillary structures and the morphology of epithelial-like cells, conspicuously lack the hallmark histological characteristics of Solitary Fibrous Tumors (SFTs). Consequently, it requires differential diagnosis from a plethora of malignant neoplasms. Moreover, the elevated malignancy level of this cohort of cases poses substantial diagnostic challenges to pathologists, compounding the complexity of accurate interpretation.
孤立性纤维性肿瘤（SFT）是一种独特的软组织肿瘤，其特征在于 NAB2-STAT6 基因的重排，与薄壁、分支、“鹿角”状血管有关。SFT 最初被归类为一种血管外皮细胞瘤（HPC）。经典的 SFT 由纺锤形到卵圆形细胞杂乱排列或呈束状排列。罕见情况下，SFT 表现出不常见的形态变体，如脂肪形成、巨细胞、去分化或上皮样变体。上皮样细胞变体几乎完全由上皮样细胞组成，呈实性或巢状排列，极为罕见且常为恶性。
本研究报告了三例位于胸外部位（右侧侧脑室、右侧腰椎、左侧骨盆）的上皮样 SFT（ESFT）。本研究中的所有受试者均为老年人，女性患者居多，占三例中的两例，仅一例为男性患者。肿瘤细胞完全由上皮样细胞组成，CD34 和 STAT-6 标志物均呈阳性。最终，大多数病例（三例中的两例）被诊断为恶性 SFT。
本研究旨在提高对 ESFT 的认识。在这些病例中，无论肿瘤细胞的起始位置、排列方式如何，如乳头状结构和上皮样细胞的形态，均明显缺乏孤立性纤维性肿瘤（SFT）的标志性组织学特征。因此，需要与众多恶性肿瘤进行鉴别诊断。此外，该组病例的恶性程度升高给病理学家带来了实质性的诊断挑战，增加了准确解读的复杂性。
