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Abstract：
OBJECTIVE: Pulmonary papillary adenoma is an extremely rare benign tumor. It is derived from type II lung cells and club cells, suggesting that it may originate from stem cells with two-way differentiation. Only one case has been reported with FGFR2-IIIb overexpression.
METHODS: Two cases of pulmonary papillary adenoma with available data on clinical features, histological morphology, immunophenotype and molecular characteristics were analyzed.
RESULTS: Both tumors were well-circumscribed unencapsulated nodules composed of papillary structures with fibrovascular cores lined by a single layer of cuboidal or columnar epithelium without necrosis, nuclear atypia and mitoses, or invasion. But malignant transformation features include complex branching structures and significantly enlarged, irregular, and crowded malignant cells in one case. Immunohistochemistry showed that the tumor cells were strongly positive for TTF1, NapsinA, EMA and CK7 and negative for CEA and P63, with a low Ki-67 proliferation index. The EGFR somatic mutation exon19:c.2236_2256delinsATC (p.E746_S752delinsI) was found in one case by next-generation sequencing (NGS) technology.
CONCLUSIONS: Pulmonary papillary adenoma is very rare. Virtually all papillary adenomas are clinically silent and discovered incidentally. They are benign tumors, and resection is curative. An EGFR 19 exon deletion mutation in a patient with this tumor type was detected for the first time by NGS, and our results suggest that the malignant transformation of pulmonary papillary adenoma may be mediated by EGFR mutation.
METHODS: Two cases of pulmonary papillary adenoma with available data on clinical features, histological morphology, immunophenotype and molecular characteristics were analyzed.
RESULTS: Both tumors were well-circumscribed unencapsulated nodules composed of papillary structures with fibrovascular cores lined by a single layer of cuboidal or columnar epithelium without necrosis, nuclear atypia and mitoses, or invasion. But malignant transformation features include complex branching structures and significantly enlarged, irregular, and crowded malignant cells in one case. Immunohistochemistry showed that the tumor cells were strongly positive for TTF1, NapsinA, EMA and CK7 and negative for CEA and P63, with a low Ki-67 proliferation index. The EGFR somatic mutation exon19:c.2236_2256delinsATC (p.E746_S752delinsI) was found in one case by next-generation sequencing (NGS) technology.
CONCLUSIONS: Pulmonary papillary adenoma is very rare. Virtually all papillary adenomas are clinically silent and discovered incidentally. They are benign tumors, and resection is curative. An EGFR 19 exon deletion mutation in a patient with this tumor type was detected for the first time by NGS, and our results suggest that the malignant transformation of pulmonary papillary adenoma may be mediated by EGFR mutation.
摘要：
目的：肺乳头状腺瘤是一种极其罕见的良性肿瘤。它来自II型肺细胞和俱乐部细胞，这表明它可能来源于双向分化的干细胞。仅报道一例FGFR2-IIIb过表达。
方法：2例肺乳头状腺瘤，有临床资料，组织学形态学,分析免疫表型和分子特征。
结果：两种肿瘤均为未包囊结节，由乳头状结构组成，纤维血管核内衬单层长方体或柱状上皮，无坏死，核异型和有丝分裂，或入侵。但是恶性转化特征包括复杂的分支结构和明显扩大，不规则,在一个案例中，拥挤的恶性细胞。免疫组化显示肿瘤细胞TTF1、NapsinA强阳性,EMA和CK7，CEA和P63阴性，Ki-67增殖指数较低。EGFR体细胞突变exon19：c.2236_2256delinsATC（p。通过下一代测序（NGS）技术在一例中发现了E746_S752delinsI）。
结论：肺乳头状腺瘤非常罕见。实际上，所有乳头状腺瘤在临床上都是沉默的，并且是偶然发现的。它们是良性肿瘤，切除是治愈性的。NGS首次检测到该类型肿瘤患者的EGFR19外显子缺失突变，我们的结果提示肺乳头状腺瘤的恶性转化可能是由EGFR突变介导的。
方法：2例肺乳头状腺瘤，有临床资料，组织学形态学,分析免疫表型和分子特征。
结果：两种肿瘤均为未包囊结节，由乳头状结构组成，纤维血管核内衬单层长方体或柱状上皮，无坏死，核异型和有丝分裂，或入侵。但是恶性转化特征包括复杂的分支结构和明显扩大，不规则,在一个案例中，拥挤的恶性细胞。免疫组化显示肿瘤细胞TTF1、NapsinA强阳性,EMA和CK7，CEA和P63阴性，Ki-67增殖指数较低。EGFR体细胞突变exon19：c.2236_2256delinsATC（p。通过下一代测序（NGS）技术在一例中发现了E746_S752delinsI）。
结论：肺乳头状腺瘤非常罕见。实际上，所有乳头状腺瘤在临床上都是沉默的，并且是偶然发现的。它们是良性肿瘤，切除是治愈性的。NGS首次检测到该类型肿瘤患者的EGFR19外显子缺失突变，我们的结果提示肺乳头状腺瘤的恶性转化可能是由EGFR突变介导的。
