Franssila K O, Ackerman L V, Brown C L, Hedinger C E
Semin Diagn Pathol. 1985 May;2(2):101-22.
The workshop participants agreed on the following points regarding follicular carcinoma: Follicular carcinoma should be divided into two groups according to its degree of invasion: encapsulated and widely invasive. Patients in the first group only occasionally develop distant metastases, whereas in the second group the prognosis is much poorer. In encapsulated follicular tumors, high cellularity and nuclear atypia should not be used as criteria of malignancy; this diagnosis should be based on the presence of vascular or capsular invasion. Only tumor thrombi occurring in vessels in or outside the capsule should be regarded as indicative of vascular invasion. Capsular invasion should be diagnosed only if penetration of the whole capsule is seen. We agree that some tumor islands within the capsule may represent true tumor invasion, but we believe that some others may be due to capsular infoldings or tangential sectioning. Whenever tumor tissue within the capsule is seen, additional tissue blocks from the capsular area should be processed in a search for capsular penetration or vascular invasion. The degree of differentiation in follicular carcinoma does not correlate to the course of disease as clearly as the degree of invasion, although the so-called insular or poorly differentiated, subtype seems to have a poorer prognosis. Thyroid carcinomas composed of large eosinophilic cells (Hürthle cell carcinomas) usually show follicular differentiation and are therefore included in the category of follicular carcinoma. The same diagnostic criteria of malignancy that apply for other follicular tumors should be used when evaluating these tumors. Although follicular carcinomas often show foci of clear cells, tumors composed solely of clear cells are rare. Most pure clear-cell tumors in the thyroid represent metastatic tumors, usually from the kidney. In the distinction of follicular carcinoma from papillary carcinoma, all differential diagnostic criteria should be used. However, in some cases, the diagnosis can be based on one criterion only, mainly the presence of widespread ground-glass nuclei or abundant neoplastic papillae in papillary carcinoma. The presence of occasional papillae in encapsulated tumors composed of large eosinophilic cells is not sufficient for the diagnosis of papillary carcinoma if the other microscopic features of this tumor are lacking.
滤泡状癌应根据其浸润程度分为两组：包膜内型和广泛浸润型。第一组患者仅偶尔发生远处转移，而第二组患者的预后则差得多。在包膜内滤泡状肿瘤中，高细胞密度和核异型性不应作为恶性肿瘤的标准；该诊断应基于血管或包膜侵犯的存在。只有在包膜内或包膜外血管中出现的肿瘤血栓才应被视为血管侵犯的指征。只有在看到整个包膜被穿透时才能诊断为包膜侵犯。我们同意包膜内的一些肿瘤岛可能代表真正的肿瘤浸润，但我们认为其他一些可能是由于包膜折叠或切线切片所致。每当在包膜内看到肿瘤组织时，应处理来自包膜区域的额外组织块，以寻找包膜穿透或血管侵犯。滤泡状癌的分化程度与疾病进程的相关性不如浸润程度明显，尽管所谓的岛状或低分化亚型似乎预后较差。由大嗜酸性细胞组成的甲状腺癌（许特莱细胞癌）通常表现为滤泡状分化，因此归入滤泡状癌类别。评估这些肿瘤时应采用与其他滤泡状肿瘤相同的恶性诊断标准。尽管滤泡状癌常出现透明细胞灶，但仅由透明细胞组成的肿瘤很少见。甲状腺中大多数纯透明细胞肿瘤为转移性肿瘤，通常来自肾脏。在鉴别滤泡状癌与乳头状癌时，应使用所有鉴别诊断标准。然而，在某些情况下，诊断可能仅基于一个标准，主要是乳头状癌中广泛存在的磨砂玻璃样核或丰富的肿瘤乳头。如果由大嗜酸性细胞组成的包膜内肿瘤缺乏乳头状癌的其他微观特征，偶尔出现乳头不足以诊断为乳头状癌。
