Brachtel Elena F, Iafrate A John, Mark Eugene J, Deshpande Vikram
Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Diagn Cytopathol. 2007 May;35(5):257-62. doi: 10.1002/dc.20617.
The initial diagnosis of lung carcinoma is frequently made by fine-needle aspiration biopsy. Novel therapeutic strategies of this disease include tyrosine kinase inhibitors (TKI), such as gefitinib (Iressa) or erlotinib (Tarceva), which target the kinase domain of epidermal growth factor receptor (EGFR). Somatic mutations of this region have been shown to predict a therapeutic response of lung carcinomas to TKI. EGFR mutations have been described in adenocarcinomas of the lung, especially the bronchioloalveolar subtype, which has both cytopathologic and histopathologic definitions. This study investigates whether tumors with EGFR mutations display a characteristic phenotype on fine-needle aspiration biopsy. We identified 37 fine-needle aspiration biopsy of lung masses on which molecular analysis for EGFR mutations was available. Molecular analysis was performed on DNA isolated from formalin-fixed, paraffin-embedded, or frozen tissue from the corresponding core biopsies/cell blocks or resection specimens followed by PCR with primers for the tyrosine kinase region exons 18-24 and nucleotide sequence analysis by gel electrophoresis. Two observers who were blinded to the mutational data assessed several cytomorphological parameters. A semiquantitative analysis included predominant tissue pattern (flat or overlapping), nuclear features (nucleoli, intranuclear inclusions, grooves), cytoplasmic qualities, and extracellular material. All cases were adenocarcinomas primary in the lung. Thirteen cases showed EGFR mutations in exons 18, 19, 20, or 21 of the tyrosine kinase domain. The 24 cases negative for the relevant mutation served as the control group. Tumors with EGFR mutations were statistically more likely to demonstrate a predominantly flat, monolayer architecture (P=0.04) with nuclear inclusions (P=0.014) and the absence of macronucleoli (P=0.001). The predominance of flat monolayers in conjunction with the absence of extracellular mucin and macronucleoli indicated the presence of EGFR mutations with a positive predictive value of 69% and a negative predictive value of 92%. All four cases with extracellular mucin were negative for the examined mutations. Some of the traditional cytomorphological features of bronchioloalveolar carcinoma, i.e., flat monolayers, intranuclear inclusions, and the absence of macronucleoli, statistically correlated with the presence of mutations within the tyrosine kinase region of EGFR. Cytomorphological features could serve as an adjunctive predictive marker of response to TKIs and possibly to other new therapies in development.
肺癌的初步诊断通常通过细针穿刺活检来进行。该疾病的新型治疗策略包括酪氨酸激酶抑制剂（TKI），如吉非替尼（易瑞沙）或厄洛替尼（特罗凯），它们靶向表皮生长因子受体（EGFR）的激酶结构域。已证明该区域的体细胞突变可预测肺癌对TKI的治疗反应。EGFR突变已在肺腺癌中被描述，尤其是细支气管肺泡亚型，其具有细胞病理学和组织病理学定义。本研究调查具有EGFR突变的肿瘤在细针穿刺活检时是否表现出特征性表型。我们鉴定了37例肺肿块的细针穿刺活检样本，这些样本可进行EGFR突变的分子分析。分子分析是对从相应的芯针活检/细胞块或切除标本的福尔马林固定、石蜡包埋或冷冻组织中分离的DNA进行的，随后用针对酪氨酸激酶区域外显子18 - 24的引物进行PCR，并通过凝胶电泳进行核苷酸序列分析。两名对突变数据不知情的观察者评估了几个细胞形态学参数。半定量分析包括主要组织模式（扁平或重叠）、核特征（核仁、核内包涵体、沟）、细胞质特征和细胞外物质。所有病例均为原发性肺腺癌。13例病例在酪氨酸激酶结构域的外显子18、19、20或21中显示EGFR突变。24例相关突变阴性的病例作为对照组。具有EGFR突变的肿瘤在统计学上更有可能表现出主要为扁平的单层结构（P = 0.04），伴有核内包涵体（P = 0.014）且无大核仁（P = 0.001）。扁平单层结构占优势，同时缺乏细胞外粘蛋白和大核仁表明存在EGFR突变，其阳性预测值为69%，阴性预测值为92%。所有4例有细胞外粘蛋白的病例所检测的突变均为阴性。细支气管肺泡癌的一些传统细胞形态学特征，即扁平单层结构、核内包涵体和无大核仁，在统计学上与EGFR酪氨酸激酶区域内突变的存在相关。细胞形态学特征可作为对TKI以及可能对其他正在研发的新疗法反应的辅助预测标志物。
