Chhieng D C, Rose D, Ludwig M E, Zakowski M F
Department of Cytology, New York University Medical Center, New York, New York, USA.
Cancer. 2000 Feb 25;90(1):24-32.
Aspirates of thymomas are distinguishable from other lesions and fine-needle aspiration (FNA) is a proven method for investigating mediastinal masses.
Thirty-four cytology specimens of thymomas from 31 patients were examined. Corresponding surgical materials were available in 32 cases. Ten cases were benign and 22 were malignant. Cytologic features of these thymomas were correlated with various histologic classification systems and with biologic behavior. Dual epithelial and lymphoid populations and irregular cohesive tissue fragments of varying proportions of lymphoid and epithelial cells were characteristic of all aspirates.
Using the Lattes-Bernatz classification, 10 cases predominately were lymphocytic, 3 cases predominately were epithelial, 3 cases predominately were spindle, 15 cases predominately were mixed, and 1 case was a thymic carcinoma. In the Muller-Hermelink classification, 3 cases were medullary, 12 were mixed, 8 predominately were cortical, 2 were cortical, 6 were well differentiated thymic carcinoma, and 1 was a poorly differentiated thymic carcinoma. In the majority of the cases the epithelial cells were round to oval. Spindle cells and a mixture of round to oval and spindle cells also were observed. No cytologic feature was found to correlate significantly with any classification scheme. Necrosis was present in 5 of the 32 aspirates, most frequently in malignant tumors. Thymomas showing predominately spindle cells frequently were encapsulated. Tumors with predominantly round to oval cells or a mixed population behaved more aggressively than those with spindle cells. Tumors that were well encapsulated and benign clinically tended to possess benign-appearing nuclei. Among the 22 invasive or malignant lesions, 8 exhibited moderate to marked cytologic atypia and 14 showed little or no atypia. No atypia was observed in benign tumors.
The presence of cytologic atypia of epithelial cells may be helpful in predicting aggressiveness. However, the absence of atypia and necrosis may not imply a benign course. Correlation with clinical and radiographic findings should be sought.
胸腺瘤的穿刺物可与其他病变相区分，细针穿刺（FNA）是一种用于检查纵隔肿块的成熟方法。
对31例患者的34份胸腺瘤细胞学标本进行了检查。32例有相应的手术材料。10例为良性，22例为恶性。这些胸腺瘤的细胞学特征与各种组织学分类系统以及生物学行为相关。所有穿刺物的特征均为双上皮和淋巴细胞群以及不同比例淋巴细胞和上皮细胞的不规则凝聚组织碎片。
采用Lattes-Bernatz分类法，10例主要为淋巴细胞型，3例主要为上皮型，3例主要为梭形细胞型，15例主要为混合型，1例为胸腺癌。在Muller-Hermelink分类法中，3例为髓质型，12例为混合型，8例主要为皮质型，2例为皮质型，6例为高分化胸腺癌，1例为低分化胸腺癌。在大多数病例中，上皮细胞呈圆形至椭圆形。也观察到梭形细胞以及圆形至椭圆形细胞与梭形细胞的混合。未发现任何细胞学特征与任何分类方案有显著相关性。32份穿刺物中有5份存在坏死，最常见于恶性肿瘤。主要为梭形细胞的胸腺瘤通常有包膜。以圆形至椭圆形细胞为主或细胞混合的肿瘤比梭形细胞肿瘤的侵袭性更强。包膜良好且临床为良性的肿瘤往往具有外观良性的细胞核。在22例浸润性或恶性病变中，8例表现为中度至显著的细胞学异型性，14例表现为轻度或无异型性。良性肿瘤未观察到异型性。
上皮细胞的细胞学异型性可能有助于预测侵袭性。然而，无异型性和坏死并不意味着病程为良性。应寻求与临床和影像学检查结果的相关性。
