Renshaw Andrew A, Haja Jennifer, Lozano Richard L, Wilbur David C
Department of Pathology, Baptist Hospital of Miami, Miami, Fla, USA.
Arch Pathol Lab Med. 2005 May;129(5):614-8. doi: 10.5858/2005-129-0614-DCTFSC.
The cytologic features of carcinoid tumor of the lung are well described. Nevertheless, some carcinoids may be difficult to distinguish from small cell carcinomas.
To correlate the cytologic features of individual cases of carcinoid tumor of the lung in fine-needle aspiration specimens in the College of American Pathologists Non-Gynecologic Cytology Program with the frequency of misclassification as small cell carcinoma.
We reviewed 1100 interpretations from 26 different cases of carcinoid tumor in lung fine-needle aspiration specimens in the College of American Pathologists Non-Gynecologic Cytology Program and correlated the cytologic features with the performance in the program.
Cases were divided into those that were frequently misclassified as small cell carcinoma (at least 20% of the responses, 19 cases) and those that were infrequently misclassified as small cell carcinoma (<10% of all responses, 7 cases). All cases had areas with classic features of carcinoid tumor. Cases were reviewed independently by 3 cytopathologists specifically looking for cytologic features that might be responsible for misclassification as small cell carcinoma. All 7 cases that were infrequently misclassified consisted of numerous monotonous well-preserved tumor cells that were either entirely round or were a mixture of round and spindle-shaped cells. Six of 7 cases showed a prominent streaming vascular pattern with tumor cells attached to the endothelial cell core. In contrast, cases that were frequently misclassified had 1 of 6 patterns that were not seen in cases that were rarely misclassified. These 6 patterns were: (1) poorly preserved and pale-staining cells with fine chromatin and a suggestion of molding (5 cases); (2) numerous large, well-preserved, spindle-shaped cells (2 cases); (3) numerous cells varying markedly in both size and shape (both round and spindle-shaped cells), with a common finding of degenerated, smudgy, small round and spindle-shaped cells (9 cases); (4) hypocellular specimens (8 cases); (5) obscuration of cells by blood (2 cases); and (6) tumor cells present predominantly in groups, with few isolated cells (8 cases). In none of these cases were mitoses or true necrosis identified.
Frequent misclassification of carcinoid tumor as small cell carcinoma in lung fine-needle aspiration specimens in this program correlates strongly with specific cytologic features, some of which are common in small cell carcinoma (fine chromatin, molding, smudgy chromatin) and others that are not (spindle-shaped cells). In addition, hypocellular specimens or specimens with cellular obscuration performed poorly, along with specimens exhibiting absence of the commonly described carcinoid feature of streaming vascularity. Awareness of these patterns may aid in avoiding misdiagnosis.
肺类癌肿瘤的细胞学特征已有详尽描述。然而，某些类癌可能难以与小细胞癌区分开来。
将美国病理学家学会非妇科细胞学项目中肺细针穿刺标本中肺类癌肿瘤个体病例的细胞学特征与被误分类为小细胞癌的频率相关联。
我们回顾了美国病理学家学会非妇科细胞学项目中26例肺细针穿刺标本中类癌肿瘤的1100份诊断结果，并将细胞学特征与该项目中的表现相关联。
病例被分为经常被误分类为小细胞癌的病例（至少20%的诊断结果，共19例）和很少被误分类为小细胞癌的病例（<10%的所有诊断结果，共7例）。所有病例均有类癌肿瘤的典型特征区域。由3位细胞病理学家独立复查病例，专门寻找可能导致被误分类为小细胞癌的细胞学特征。所有7例很少被误分类的病例均由大量形态单一、保存良好的肿瘤细胞组成，这些细胞要么完全呈圆形，要么是圆形和梭形细胞的混合。7例中的6例显示出明显的血流样血管模式，肿瘤细胞附着在内皮细胞核心上。相比之下，经常被误分类的病例具有6种模式中的1种，而很少被误分类的病例中未见到这些模式。这6种模式为：（1）保存不佳、淡染的细胞，染色质细腻，有核膜内陷迹象（5例）；（2）大量大的、保存良好的梭形细胞（2例）；（3）大量大小和形状差异明显的细胞（圆形和梭形细胞均有），常见退变、模糊的小圆形和梭形细胞（9例）；（4）细胞少的标本（8例）；（5）血液遮盖细胞（2例）；（6）肿瘤细胞主要成簇存在，单个细胞很少（8例）。在这些病例中均未发现有丝分裂或真正的坏死。
在该项目中，肺细针穿刺标本中类癌肿瘤经常被误分类为小细胞癌与特定的细胞学特征密切相关，其中一些特征在小细胞癌中常见（细腻的染色质、核膜内陷、模糊的染色质），而另一些则不然（梭形细胞）。此外，细胞少的标本或有细胞遮盖的标本表现不佳，以及缺乏通常描述的类癌血流样血管特征的标本也是如此。了解这些模式可能有助于避免误诊。
