Differences between low and high grade fetal adenocarcinoma of the lung: a clinicopathological and molecular study

Molecular landscape and multi-omic measurements of heterogeneity in fetal adenocarcinoma of the lung

Fetal adenocarcinoma of the lung (FLAC) is a rare form of lung adenocarcinoma and was divided into high-grade (H-FLAC) and low-grade (L-FLAC) subtypes. Despite the existence of some small case series studies, a comprehensive multi-omics study of FLAC has yet to be undertaken. In this study, we depicted the multi-omics landscapes of this rare lung cancer type by performing multi-regional sampling on 20 FLAC cases. A comparison of multi-omics profiles revealed significant differences between H-FLAC and L-FLAC in a multi-omic landscape. Two subtypes also showed distinct relationships between multi-layer intratumor heterogeneity (ITH). We discovered that a lower genetic ITH was significantly associated with worse recurrence-free survival and overall survival in FLAC patients, whereas higher methylation ITH in H-FLAC patients suggested a short survival. Our findings highlight the complex interplay between genetic and transcriptional heterogeneity in FLAC and suggest that different types of ITH may have distinct implications for patient prognosis.

Clinical and Pathological Characteristics and Prognosis of Lung Adenocarcinoma With High-Grade Fetal Features: A Retrospective Analysis

Fetal adenocarcinoma of the lung is a rare tumor. The clinical and pathological characteristics, treatment, and prognosis of patients with lung adenocarcinoma with fetal lung-like morphology were retrospectively investigated. The tumors of 9 patients with lung adenocarcinoma contained fetal lung-like morphology. One patient had pure-type high-grade fetal adenocarcinoma. Two patients had more than 50% high-grade fetal adenocarcinoma. Six specimens accounted for < 50% of the high-grade fetal features. It occurred in 7 men and 2 women. The median age at diagnosis was 62.0 years. Thyroid transcription factor-1 was frequently expressed in 8 specimens. All 9 specimens showed high rates of immunopositivity for β-catenin and E-cadherin. Three specimens showed nuclear β-catenin staining. Some patients showed immune expression of CDX2, α-fetoprotein (AFP), SALL4, and Glypican-3. Three of these specimens were diffusely strongly positive for p53, including 1 mixed-type high-grade fetal adenocarcinoma and 2 lung adenocarcinomas with high-grade fetal features. However, the other 6 patients had wild-type p53, including 1 pure-type high-grade fetal adenocarcinoma. PD-L1 was not expressed in all patients. Epidermal growth factor receptor mutations were detected in 1 patient. All patients were diagnosed using surgical samples. During the follow-up period of 36 months (range: 1-92 months), 3 patients received chemotherapy. One patient underwent radiotherapy. Two patients experienced recurrences. No patient died. PD-L1 expression status suggests a poor response to immune checkpoint therapy. The prognosis of the patient was relatively good.

A component of high-grade fetal lung adenocarcinoma diagnosed as the cause of lymph node metastasis

High-grade fetal lung adenocarcinoma (H-FLAC) is a rare type of tumor. There have been no reports demonstrating the degree of metastatic susceptibility of this tumor type. In this report, we describe a case in which 15% of the adenocarcinoma components were H-FLAC diagnosed as the cause of lymph node metastasis. A 75-year-old man presented with suspected primary lung cancer (clinical stage IIA, T2bN0M0) and underwent left upper lobectomy and superior mediastinal lymph node dissection. Postoperative histopathology revealed lung cancer with only lobar bronchial lymph node (#11) metastasis. Approximately 60% of the invasive adenocarcinoma showed a papillary morphology, 25% showed a lepidic morphology, and 15% showed a fetal morphology. The histomorphological and immunohistological features of #11 metastasis were similar to those of H-FLAC. Herein, we report a rare and important case of H-FLAC with proven lymph node metastasis, showing that even a small amount of H-FLAC tissue can cause metastasis.

[High-grade Fetal Adenocarcinoma of the Lung with Scalp Metastasis: A Case Report]

Fetal adenocarcinoma of the lung (FLAC) is a rare tumor. Due to its different clinicopathological features, biological behavior and clinical outcome, FLAC is classified into low-grade FLAC (L-FLAC) and high-grade FLAC (H-FLAC). Most patients with H-FLAC are middle-aged heavy smokers. Here, we describe an extremely rare case of a young male patient who denies smoking and initially presents with a mass on the top of the head and is eventually diagnosed with H-FLAC. The aim of this article is to improve the understanding and awareness of FLAC, and increase the attention to the disease, so as to prevent the underdiagnosis and misdiagnosis of the disease, strengthen early identification and accurate diagnosis, and promote subsequent effective treatment and improve prognosis.
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Cytomorphology of pulmonary low-grade fetal adenocarcinoma in bronchial brushing specimen prepared by BD SurePath: A case report and literature review

Low-grade fetal adenocarcinoma (LGFA) of the lung is a rare subtype of lung adenocarcinoma, resembling developing fetal lung in pseudoglandular stage. LGFA is very different to conventional adenocarcinoma. It is more likely to occur in young adults and has favorable prognosis. Reports on the cytology of LGFA are very rare; only 10 cases have been reported previously in the English literature. Our case report adds to the cytological features of this tumor sampled by bronchial brushing and is the first case prepared by the BD SurePath liquid-based cytology. We present a case of 31-year-old male with endobronchial involvement of right bronchus. The cytological features of diagnostic clues for LGFA include three dimensional glandular arrangements of uniform, columnar cells with inconspicuous nucleoli. It is important to recognize this rare and favorable variant of lung adenocarcinoma. In this report, we present the cytological and pathological features of LGFA, along with a literature review.

High-grade fetal adenocarcinoma of the lung misdiagnosed as male breast carcinoma: a case report and literature review

Background and aim

High-grade fetal adenocarcinoma of the lung (HG-FLAC) is a specific subtype of lung adenocarcinoma with a poor prognosis. A lack of understanding exists because of the rarity of this disease. This study aimed to present a case of HG-FLAC with multiple metastases misdiagnosed as male breast carcinoma at the initial diagnosis.

Case presentation

The patient visited our hospital due to a month-long cough. The chest computed tomography (CT) scan revealed a mass in the left lung and chest wall, accompanied by enlargement of mediastinal lymph nodes. The magnetic resonance imaging indicated potential metastatic lesions in the brain and adrenal glands. The patient underwent a biopsy of the lesion in the right chest wall. The pathological and immunohistochemical findings indicated a high possibility of male breast cancer. However, the clinical features did not support this diagnosis. Therefore, a CT-guided percutaneous lung biopsy was performed, and the pathological examination finally indicated HG-FLAC.

Conclusions

We presented a complex yet interesting case in which HG-FLAC was misdiagnosed as male breast cancer. Our interesting case may stimulate discussions about the methods to manage patients with HG-FLAC.

KMT2C expression and DNA homologous recombination repair factors in lung cancers with a high-grade fetal adenocarcinoma component

Background

High-grade fetal adenocarcinoma of the lung (H-FLAC) is a rare variant of pulmonary adenocarcinoma. Our previous study showed a high frequency of KMT2C mutations in lung cancers with an H-FLAC component, showing that KMT2C dysfunction may be associated with the biological features of H-FLACs.

Methods

In this study, we performed RNA sequencing and immunohistochemical analysis to identify the differentially expressed genes and corresponding pathways associated with H-FLACs, compared with common adenocarcinomas.

Results

Ingenuity pathway analysis based on RNA sequencing data revealed that DNA homologous recombination repair (HRR) pathways were significantly inactivated in H-FLAC. Expression of KMT2C, ATM, ATR, and BRCA2 was significantly lower in H-FLACs than in common adenocarcinomas, and BRCA1 expression showed a decreasing trend. Pearson correlation analyses for all cases revealed that KMT2C expression showed a strong positive correlation (R>0.7) with the expression of ATR, BRCA1, and BRCA2 genes and a moderately positive correlation with ATM expression (R=0.47). Immunohistochemical analysis showed significantly lower levels of KMT2C, ATM, ATR, and BRCA2 expression in H-FLACs than in common adenocarcinomas, and a trend of lower BRCA1 levels. Additionally, KMT2C expression showed a weak to moderate correlation with that of ATM, ATR, BRCA1, and BRCA2.

Conclusions

Cancers containing H-FLAC components showed lower levels of KMT2C and HRR factors than common lung adenocarcinomas, and their levels exhibited a positive correlation. These results support the hypothesis that loss of KMT2C function decreases the expression of the HRR factors in H-FLACs. H-FLACs with low KMT2C expression may be a good indication for poly (ADP-ribose) polymerase (PARP) inhibitor-based therapy.

Successful treatment with atezolizumab combination chemotherapy in a patient with high-grade fetal adenocarcinoma of the lung: A case report

High-grade fetal lung adenocarcinoma (H-FLAC) is a rare tumor, with little known of its response to chemotherapy with or without an immune checkpoint inhibitor or of its molecular profile. We report the first case of a 56-year-old man with stage IV H-FLAC who was successfully treated with carboplatin plus nab-paclitaxel in combination with atezolizumab. In addition, the tumor was found to be positive for amplification of the human epidermal growth factor receptor 2 gene.

[A Review on Pathological High-risk Factors and Postoperative Adjuvant Chemotherapy in Stage IA Lung Adenocarcinoma]

The survival rate needs to be improved in early stage non-small cell lung cancer patients. The risk of recurrence is relatively high in invasive adenocarcinoma patients with a solid or micropapillary component, lymphovascular invasion or tumor spread through air spaces. Systemic treatment options including radical surgical resection should be explored for this population. Adjuvant chemotherapy is not recommended for patients in stage IA in current guidelines. This article is a review on the research progress of the above pathological high-risk factors and the role of adjuvant chemotherapy in patients with pathological high-risk factors in stage IA lung adenocarcinoma.
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A case report of low grade fetal lung adenocarcinoma with TP53 mutation

RATIONALE

Fetal lung adenocarcinoma (FLAC) is a rare malignant tumor that occurs in the alveolar epithelium. FLAC, as a distinct entity, is a malignancy with a very low incidence, accounting for less than 0.5% of all lung tumors, with a high rate of misdiagnosis due to its rarity, lack of typical presentation and imaging signs. According to histopathological differences, FLAC is further divided into 2 types: low-grade FLAC and high-grade FLAC. In the article, we report a young woman who was diagnosed with low-grade fetal-type lung adenocarcinoma.

PATIENT CONCERNS

An 18-year-old female patient was admitted due to cough and chest distress.

DIAGNOSIS

The final pathological examination confirmed that the lesion was a low-grade fetal lung adenocarcinoma.

INTERVENTIONS

The patient underwent thoracoscopic left lower lobectomy and regional lymph node dissection.

OUTCOMES

The postoperative course was stable, and no recurrence was observed 1 year after operation.

LESSONS

To the best of our knowledge, there are no previous case reports of low-grade fetal-type adenocarcinoma, TP53 gene mutation, and the significance of its mutation is not extensively studies. FLAC, although extremely rare, is considered in the differential diagnosis of lung cancer. In addition, biopsy, histopathology, and specific immunohistochemical staining of larger tissue specimens are helpful for accurate diagnosis of FLAC.

Morphological and Molecular Characteristics in Low Grade Fetal Adenocarcinoma of the Lung: Two Case Reports and Literature Review

Background: Low-grade fetal adenocarcinoma of the lung is a rare pulmonary tumor resembling fetal lung histologically. Due to its rarity, there is limited information regarding the pathogenesis and biological characteristics of low-grade fetal adenocarcinoma of the lung. Here, we describe two cases of low-grade fetal adenocarcinoma of the lung treated at our hospital and summarize cases of low-grade fetal adenocarcinoma of the lung reported in the literature. Case presentation: We examined two cases (one woman and one man; 30 and 67 years old, respectively). Histologically, tumor tissues from both cases had a complex glandular component with clear cuboidal and columnar cells that resembled the histological features of fetal lung. In some areas, squamous morules were prominent. Immunohistochemically, nuclear/cytoplasmic expression of β-catenin was detected in both cases. Mutation analysis revealed a CTNNB1 mutation in both cases and a DICER1 mutation in 1 case. No mutations in EGFR, BRAF, KRAS, or PIK3CA were found. Conclusions: Low-grade fetal adenocarcinoma of the lung showed a high frequency of CTNNB1 mutations and low frequencies of EGFR, KRAS, BRAF, and PIK3CA mutations in our examined cases and in previous studies. This rare tumor has unique clinicopathological characteristics with specific genetic aberrations involving the Wnt pathway. These results provide a molecular basis for development of new therapies to treat these tumors.

The 2021 WHO Classification of Lung Tumors: Impact of advances since 2015

The 2021 World Health Organisation (WHO) Classification of Thoracic Tumours was published earlier this year, with classification of lung tumors being one of the chapters. The principles remain those of using morphology first, supported by immunohistochemistry and then molecular techniques. In 2015, there was particular emphasis on using immunohistochemistry to make classification more accurate. In 2021, there is greater emphasis throughout the book on advances in molecular pathology across all tumor types. Major features within this edition are 1) broader emphasis on genetic testing than in the 2015 WHO Classification, 2) a chapter entirely dedicated to the classification of small diagnostic samples, 3) continued recommendation to document percentages of histological patterns in invasive non-mucinous adenocarcinomas, with utilization of these features to apply a formal grading system, as well as using only invasive size for T-factor size determination in part lepidic non-mucinous lung adenocarcinomas as recommended by the 8^th Edition TNM Classification, 4) recognition of spread through airspaces (STAS) as a histological feature with prognostic significance, 5) moving lymphoepithelial carcinoma to squamous cell carcinomas, 6) update on evolving concepts in lung neuroendocrine neoplasm classification, 7) recognition of bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT) as a new entity within the adenoma subgroup, 8) recognition of thoracic SMARCA4-deficient undifferentiated tumor, and 9) inclusion of essential and desirable diagnostic criteria for each tumor.

Morphologic, Immunohistochemical, and Genetic Differences Between High-grade and Low-grade Fetal Adenocarcinomas of the Lung

Fetal adenocarcinoma of the lung (FLAC) is a rare lung tumor classified into low-grade fetal adenocarcinoma of the lung (LG-FLAC) and high-grade fetal adenocarcinoma of the lung (HG-FLAC). It remains debatable whether HG-FLAC is a subset of FLAC or a distinct subtype of the conventional lung adenocarcinoma (CLA). In this study, samples of 4 LG-FLAC and 2 HG-FLAC cases were examined, and the clinicopathologic, immunohistochemical (IHC), and mutational differences between the 2 subtypes were analyzed using literature review. Morphologically, LG-FLACs had a pure pattern with complex glandular architecture composed of cells with subnuclear and supranuclear vacuoles, mimicking a developing fetal lung. In contrast, HG-FLACs contained both fetal lung-like (FLL) and CLA components. With regard to IHC markers, β-catenin exhibited a nuclear/cytoplasmic staining pattern in LG-FLACs but a membranous staining pattern in HG-FLACs. Furthermore, p53 was expressed diffusely and strongly in HG-FLACs, whereas in LG-FLACs, p53 staining was completely absent. Using next-generation sequencing targeting a 1021-gene panel, mutations of CTNNB1 and DICER1 were detected in all 4 LG-FLAC samples, and a novel mutation, MYCN P44L, was discovered in 2 LG-FLAC samples. DNA samples of the FLL and CLA components of HG-FLACs were separately extracted and sequenced. The FLL component harbored no CTNNB1, DICER1, or MYCN mutations; moreover, the FLL genetic profile largely overlapped with that of the CLA component. The morphologic, IHC, and genetic features of HG-FLAC indicate that it is a variant of CLA rather than a subset of FLAC. Thus, HG-FLAC should be treated differently from LG-FLAC.

Novel genetic characteristics in low-grade fetal adenocarcinoma of the lung

Background

Low‐grade fetal adenocarcinoma of the lung (L‐FLAC) is a rare subtype of lung adenocarcinoma with undetermined histological features and genetic abnormalities. In this study, we attempted to investigate the pathological characteristics and genomic profiles of L‐FLAC.

Methods

Among 9839 cases of primary lung adenocarcinoma resected at Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College between January 2011 and June 2016, three cases diagnosed with L‐FLAC were selected. An immunohistochemical profile and whole exome sequencing (WES) using tumor and normal tissues was conducted. The last follow‐up date of patients was January 2021.

Results

Three cases diagnosed with L‐FLAC were finally screened, suggesting a percentage of 0.03%. All three patients were male and diagnosed as stage I following radical lobectomy. The missense variant was found to be the major gene mutation type using WES. CTNNB1 and DICER1 were the two most frequent gene mutations. All cases demonstrated positive TTF‐1 expression. In addition, two patients showed positive expression of β‐catenin (nuclear/cytoplasmic expression), CgA and Sny. Negative expression of PD‐L1 in tumor cells was observed in all three cases. One case with a relatively high tumor mutation burden (TMB) (2.18 mut/Mb) had an inferior overall survival of 11.5 months. However, the other two cases with a lower TMB (0.12 and 0.74 mut/Mb) still acquired disease‐free status up to the last follow‐up date.

Conclusions

L‐FLAC has a specific molecular background which is different from lung adenocarcinoma. Furthermore, gene heterogeneity was found and might be the reason for a dramatically different prognosis in these L‐FLAC patients.

Comprehensive molecular analysis of genomic profiles and PD-L1 expression in lung adenocarcinoma with a high-grade fetal adenocarcinoma component

Background

Fetal adenocarcinoma of the lung is a rare variant of lung adenocarcinoma and is subcategorized into low-grade and high-grade (H-FLAC) fetal adenocarcinoma. We previously reported poor prognosis in pulmonary adenocarcinomas with an H-FLAC component; however, the genetic abnormalities involved in H-FLAC remain unclear. Therefore, this study aimed to elucidate molecular abnormalities as potential therapeutic targets for H-FLACs.

Methods

We performed immunohistochemical analysis and comprehensive genetic analyses using whole-exome sequencing in 16 lung cancer samples with an H-FLAC component. DNA was extracted from formalin-fixed paraffin-embedded tissues after macrodissection of the H-FLAC component.

Results

Cancer-related mutations were identified in TP53 (7/16 cases), KMT2C (6/16 cases), KRAS (4/16 cases), NF1 (3/16 cases), STK11 (3/16 cases), CTNNB1 (2/16 cases), and EGFR (1/16 cases). A high tumor mutation burden of ≥10 mutations per megabase was observed in 3/16 cases. A high microsatellite instability was not detected in any case. Based on the cosine similarity with the Catalogue of Somatic Mutations in Cancer mutational signatures, H-FLACs were hierarchically clustered into three types: common adenocarcinoma-like (five cases), surfactant-deficient (ten cases), and signatures 2 and 13-related (one case). All common adenocarcinoma-like cases presented thyroid transcription factor-1 (TTF-1) expression, whereas surfactant-deficient cases often presented loss of TTF-1 and surfactant protein expression and included cases with mutations in the surfactant system genes NKX2-1 and SFTPC. H-FLACs displayed low programmed death ligand-1 (PD-L1) expression (1–49% of tumor cells) in 5/16 cases, and no case displayed high PD-L1 expression (≥50% of tumor cells).

Conclusions

This study indicates that lung cancers with an H-FLAC component rarely harbor currently targetable driver gene mutations for lung cancer but display a high frequency of KMT2C mutations. The microsatellite instability, tumor mutation burden, and PD-L1 expression status suggest a poor response to immune checkpoint therapy.

High-grade fetal adenocarcinoma of the lung with abnormal expression of alpha-fetoprotein in a female patient: Case report

INTRODUCTION

Fetal adenocarcinoma of the lung (FLAC) is an extremely rare tumor. Due to its rarity, most of the knowledge about FLAC comes from case reports. FLAC is an invasive adenocarcinoma that is similar to the fetal lung in the pseudo-glandular stage (8-16 weeks of gestation). Owing to the differences in histopathology and clinical process, FLAC has been further divided into low-level (L-FLAC) and high-level (H-FLAC). H-FLAC is usually associated with other conventional types of lung adenocarcinoma. Lung adenocarcinoma that produces alpha-fetoprotein (AFP) is a rare type of lung cancer. Its characteristics have not been fully elucidated.

PATIENTS CONCERNS

We recently encountered this type of FLAC in a 51-year-old female patient. A computed tomography (CT) scan of the chest revealed a 74 × 51-mm sized tumor in the lingual segment of the superior lobe of the left lung. Among the tumor markers, serum AFP was elevated (816.2 ng/mL).

PRIMARY DIAGNOSIS, INTERVENTIONS, AND OUTCOMES

The diagnosis of FLAC in this patient was confirmed by bronchoscopy with lung biopsy. Through a thoracoscope, left lung pneumonectomy, and mediastinal lymph node dissection were performed. The postoperative pathological results were consistent with the preoperative diagnosis of H-FLAC. Western blotting showed the difference in the AFP expression between the normal lung tissue and the cancerous lung tissue. Eventually, the diagnosis was AFP-producing H-FLAC. Using an immunohistochemical marker for AFP, cancer cells were shown to express AFP, specifically in their nuclei. After the operation, the patient underwent conventional chemotherapy. Her serum AFP gradually decreased over the course of 2 weeks.

CONCLUSION

Presently, specific tumor markers for the diagnosis of lung cancer have not been established. To the best of our knowledge, this is the first case of abnormal AFP expression in a patient with H-FLAC. It may provide a basis for the clinical diagnosis of H-FLAC, a rare tumor, and AFP may be considered as a specific tumor marker.

Coexistence of Low-Grade Fetal Adenocarcinoma and Adenocarcinoma in situ of the Lung Harboring Different Genetic Mutations: A Case Report and Review of Literature

Low-grade fetal lung adenocarcinoma (L-FLAC) is an exceptionally rare pulmonary tumor, presenting with unclear histological and molecular features. In particular, the potential driver genes of L-FLAC remain elusive. To date, only five reports have documented genetic aberrations in L-FLAC. In the current study, we describe an unusual case of L-FLAC coexisting with adenocarcinoma in situ (AIS) of the lung, harboring different genetic mutations. A 39-year-old non-smoker female patient was referred to our hospital with the chief complaint of dyspnea for 20 days. Chest computed tomography (CT) revealed a 2.5×1.5×1.5 cm nodule in the right middle lobe, with no mediastinal lymph node enlargement or distant metastases. Thoracoscopic surgery was performed to remove the nodules. Histopathological analysis of the tissue sections, based on findings from immunohistochemical staining, confirmed a diagnosis of L-FLAC coexisting with AIS of the lung. Next-generation sequencing revealed L-FLAC-based mutations in DICER1 and CTNNB1, and AIS harboring KRAS mutations. Currently, the patient remains recurrence-free 17 months after the initial diagnosis. This report presents the first case demonstrating the coexistence of L-FLAC and AIS in the same pulmonary nodule, harboring different genetic mutations. Based on the literature review, this is the second reported case of L-FLAC bearing DICER1 mutations.

Pulmonary high-grade fetal adenocarcinoma associated with cystic airspace: A case report

Lung cancers associated with cystic airspaces have a life‐threatening risk of a missed or delayed diagnosis. Here, we report a case of pulmonary high‐grade fetal adenocarcinoma, a rare lung carcinoma associated with cystic airspaces, as confirmed by computed tomography (CT) scan. A 73‐year‐old asymptomatic male with a 52‐pack a year smoking habit was referred to our hospital. Lung CT showed a thin‐walled cystic space with exophytic and endophytic solid nodules along the cyst wall. After surgery, histological analysis of a resected lung specimen revealed a pure high‐grade fetal adenocarcinoma probably associated with emphysematous bullae in pulmonary emphysema, suggesting smoking contributed to this pure form, as well as the emphysema. In conclusion, when treating elderly men with a smoking history, physicians need to carefully examine the walls of cystic airspaces on CT for fetal adenocarcinoma.

Key points

Significant findings of the study•

Pulmonary high‐grade fetal adenocarcinoma may be associated with emphysematous bullae manifesting as cystic air spaces as shown by computed tomography.

What this study adds•

When scanning by computed tomography, physicians should carefully examine the pulmonary cystic airspace walls in elderly men with a smoking history.

Co-existence of well-differentiated fetal adenocarcinoma of the lung with tuberculosis in a young female: A rare case report

RATIONALE

Fetal adenocarcinoma of the lung (FLAC) with fetal lung-like morphology is a rare entity of pulmonary adenocarcinoma. Well-differentiated fetal adenocarcinoma (WDFA) belongs to its the low-grade form, which possesses a relatively favorable prognosis. Tuberculosis (TB) is an aggressive infectious disease that has been ranked as one of the top 10 causes of death worldwide. There may be a connection between the 2 and attention should be paid to the differential diagnosis.

PATIENT CONCERNS

A 28-year-old non-smoking female was admitted with signs of hemoptysis, and she had been coughing up phlegm for 5 years. The patient was previously diagnosed with TB in another hospital, and underwent an anti-TB regimen.

DIAGNOSIS

The co-existence of WDFA and TB was confirmed via histopathological evaluation of postoperative samples.

INTERVENTIONS

The patient was subjected to a right lower lobectomy together with a wedge resection of the right upper lobe using video-assisted thoracoscopic surgery, with systemic lymphadenectomy.

OUTCOMES

The patient tolerated the surgical procedure well and underwent an uneventful postoperative course.

LESSONS

To our knowledge, no previous reports exist of cases with WDFA accompanied by TB. The present case indicated that a prior diagnosis of TB might predispose to lung cancer regardless of smoking history. It is also essential to distinguish WDFA from TB because of the similarity in clinical features and sites of pathological changes. Patients with WDFA usually have a better prognosis and surgery is the preferred treatment.

Adenocarcinoma with fetal features invading the right superior sulcus treated with neoadjuvant chemoradiotherapy followed by complete video-assisted thoracoscopic right upper lobectomy: a case report

BACKGROUND

Fetal adenocarcinoma of the lung is a rare lung neoplasm that accounts for only 0.5% of all primary lung cancers. Because of its rarity, effective treatments for the management of the tumor are poorly understood. We herein report a case of adenocarcinoma with fetal features of the lung with invasion of the right superior sulcus that was treated with neoadjuvant chemoradiotherapy followed by surgical resection.

CASE PRESENTATION

A 54-year-old man was referred to a medical institution due to right inner forearm pain. On computed tomography of the chest, a 56-mm mass with invasion of right superior sulcus was discovered. Bronchoscopic biopsy revealed non-small cell lung carcinoma. We performed concurrent chemotherapy (2 cycles of cisplatin and vinorelbine) and thoracic radiation therapy (40 Gy in 20 fractions). As the result of extreme tumor reduction after neoadjuvant chemoradiotherapy, we could perform right upper lobectomy by complete video-assisted thoracoscopic surgery. Since no viable cancer cells were detected from the pathological examination of the resected tissue, the specimen obtained by bronchoscopic biopsy was reexamined by immunohistochemistry. The analysis supported a pathologic diagnosis of adenocarcinoma with fetal features.

CONCLUSIONS

We experienced a case of adenocarcinoma with fetal features of the lung in which the patient showed a complete response to neoadjuvant chemoradiotherapy. In addition, the tumor invading the right superior sulcus was completely resected by video-assisted thoracoscopic lobectomy. Neoadjuvant chemoradiotherapy followed by surgery may be also an effective treatment for advanced-stage high-grade fetal adenocarcinoma of the lung, similarly to other subtypes of advanced-stage primary lung cancer.

[High-grade Fetal Adenocarcinoma of the Lung: A Case Report]

胎儿型肺腺癌属极其罕见的肺恶性肿瘤，2011年由国际肺癌研究协会、美国胸科学会和欧洲呼吸学会共同制定的国际多学科肺腺癌新分类将胎儿型肺腺癌归为浸润性腺癌的变异型，并将其分为低级别、高级别两类，二者临床病理特点和生物学行为不尽相同。本文报道高级别胎儿型肺腺癌1例，并结合文献总结胎儿型肺腺癌的临床病理特点。

Pulmonary adenocarcinoma with high-grade fetal adenocarcinoma component has a poor prognosis, comparable to that of micropapillary adenocarcinoma

Fetal adenocarcinoma is a rare variant of lung adenocarcinoma, which is subcategorized into low-grade and high-grade forms. High-grade fetal adenocarcinoma confers worse prognosis than low-grade fetal adenocarcinoma, but the prognostic differences between high-grade fetal adenocarcinoma and conventional lung adenocarcinoma are unknown. We reviewed tissue sections of 3719 cases of surgically resected primary lung cancers and found 53 lung cancers with a high-grade fetal adenocarcinoma component. We analyzed their clinicopathological and immunohistochemical features, and performed a prognostic analysis of adenocarcinomas with the fetal-type component. We further analyzed the prognostic differences between adenocarcinomas with the fetal-type component and conventional adenocarcinomas without the fetal-type component. Lung cancers with the fetal-type component predominantly occurred in elderly men with a smoking history. Twenty-nine patients had stage I disease, 13 patients had stage II, and 11 patients had stage III. The fetal-type histology was combined with conventional-type adenocarcinoma (41 cases), squamous cell carcinoma (5 cases), large cell neuroendocrine carcinoma (5 cases), enteric adenocarcinoma (2 cases), and small cell carcinoma (1 case). The fetal-type component showed immunopositivity for α-fetoprotein (39%), glypican-3 (37%), and SALL4 (17%). The 5-year overall survivals of fetal-type-predominant and fetal-type-nonpredominant patients were 44 and 56%, respectively (P = 0.962). The 5-year overall survivals of lepidic-, acinar-, papillary-, solid-, and micropapillary-predominant adenocarcinomas, invasive mucinous adenocarcinomas, and adenocarcinomas with the fetal-type component were 94, 82, 77, 69, 57, 83, and 41%, respectively (P < 0.001). Univariate and multivariate analyses showed that adenocarcinomas with the fetal-type component had a significantly lower overall survival rate than the other histological subtypes, except for the micropapillary-predominant subtype. Our study demonstrated that adenocarcinomas with the fetal-type component had a poor prognosis that was comparable to that of micropapillary adenocarcinoma. The presence of the high-grade fetal adenocarcinoma component in lung adenocarcinomas is an important prognostic marker.

Comprehensive review of fetal adenocarcinoma of the lung

Fetal adenocarcinoma of the lung (FLAC) is a rare tumor. It accounts for ~0.1%-0.5% of all pulmonary neoplasms. Due to its rarity, much of the world literature regarding FLAC comes from case reports and case series. FLAC is an adenocarcinoma resembling developing fetal lung in its pseudoglandular stage (8-16 weeks of gestation). It is distinguishable from pulmonary blastoma (PB) because it lacks the mesenchymal component which is a hallmark finding in PB. Due to differences in histopathology and clinical course, FLAC has been further categorized into low-grade (L-FLAC) and high-grade (H-FLAC) forms. L-FLAC displays low nuclear atypia and prominent morule formation and has a pure pattern. H-FLAC typically presents with at least 50% fetal morphology, and is often associated with other conventional types of lung adenocarcinoma. FLAC expresses neuroendocrine markers and thyroid transcription factor 1 in most cases. L-FLAC has an aberrant nuclear/cytoplasmic expression of β-catenin and presents mutations in this gene. H-FLAC overexpresses p53. These tumors have a very low frequency of mutations in KRAS and EGFR; it is thought that they are different from a molecular point of view to conventional lung adenocarcinomas. Approximately 25%-40% of patients are asymptomatic at presentation; most of them are incidental findings on chest radiographs. H-FLAC is more common in elderly male patients, with a heavy smoking history. L-FLAC tends to occur in young females. Patients with L-FLAC are usually diagnosed with stage I-II disease, while patients with H-FLAC usually present with a more advanced-stage disease. Poor prognostic factors for FLAC are thoracic lymphadenopathy, metastases at diagnosis, and tumor recurrence; however, the 10-year survival for FLAC is estimated at 75%.

Blastomatoid pulmonary carcinosarcoma: A rare case report and review of the literature

A 65‐year‐old never‐smoking woman presented to a local hospital, because an abnormal shadow was detected at the right lower lung field by annual chest X‐ray. Computed tomography (CT) revealed a 5‐cm tumor in segment 6 of her right lung and an enlarged subcarinal lymph node, suggesting metastasis. The lung tumor was diagnosed as adenocarcinoma by a CT‐guided percutaneous needle biopsy. She was referred to our hospital and underwent right lower lobectomy with lymph node dissection (ND2a‐2). A histopathological examination of the tumor showed a biphasic proliferation made of carcinomatous and sarcomatous components. The carcinomatous component consisted of glandular structures of atypical cells that possessed chromatin‐rich nuclear and clear cytoplasm, confirming high‐grade fetal adenocarcinoma. The sarcomatous component consisted of immature spindle cells that differentiated into chondrosarcoma. Immunohistochemically, the glandular structures expressed membranous beta‐catenin, and the ultimate diagnosis was blastomatoid variant of pulmonary carcinosarcoma. She received four courses of cisplatin plus vinorelbine as adjuvant chemotherapy and remained alive with neither recurrence nor distant metastasis at two and a half years after the operation. We experienced a rare case of blastomatoid pulmonary carcinoasarcoma.

Novel gene mutations in well-differentiated fetal adenocarcinoma of the lung in the next generation sequencing era

OBJECTIVES

Since well-differentiated fetal adenocarcinoma of lung (WDFA) is an extremely rare subtype of invasive lung adenocarcinoma, histologic features, biomarkers and molecular aberrant of it are not fully determined. This article aims to investigate the clinic-pathologic details and potential driver genes of WDFA.

MATERIALS AND METHODS

Two cases of WDFA were selected from a large cohort of 730 cases of primary adenocarcinoma of the lung resected in West China Hospital of Sichuan University between January 2016 and June 2017, retrospectively. Both of them were conducted to immunohistochemical profile and gene mutation analysis by using 56-parelle-NGS.

RESULTS

Microscopically, besides conventional histologic characteristics of WDFA, such as well-differentiated glands composed of obvious glycogen-rich cells and squamoid morules formation, remarkable proliferation of benign fibrous tissue, focal necrosis and mitoses were found. Unlike the common adenocarcinomas of the lung, WDFAs showed nuclear/cytoplasmic expression of β-catenin, diffuse expression for TTF-1, and focal for Napsin A. Furthermore, molecular analysis demonstrated two novel missense gene mutations of BRCA2 and TSC2, as well as the classical CTNNB1 gene mutation and silent mutation of DDR2 gene.

CONCLUSIONS

This report presents the first case with two novel gene mutations of the WDFA, suggesting that in addition to β-catenin, BRCA2 and TSC2 might play some important roles in up-regulation of Wnt signaling pathway. Moreover, use of NGS technique is helpful to understand the biology of this rare neoplasm and provide the potential gene for targeted therapy.

Pure high-grade fetal adenocarcinoma of the lung: a case report

Background

Pure high-grade fetal adenocarcinoma of the lung (H-FLAC) is a very rare tumor.

Case presentation

An annual check-up revealed an abnormal shadow in the left middle lung field of a 63-year-old Japanese man. Chest computed tomography (CT) showed a 3.6 × 2.8 cm pulmonary lesion with clear boundary in the left upper lobe. A transbronchial lung biopsy revealed non-small cell carcinoma. A left upper lobectomy and mediastinal lymph node dissection were performed. Histologically, the tumor consisted of solid proliferation of atypical cell with clear cytoplasm. Another histological component and morulae were not contained. Immunohistochemically, the tumor was focally positive for alpha-fetoprotein (AFP) and beta-catenin in the cell membrane. Accordingly, we made the diagnosis of pure H-FLAC, pT2aN2M0, stage IIIA. Two courses of adjuvant chemotherapy (cisplatin and vinorelbine) were administered but then the treatment was discontinued due to the patient’s adverse reaction. At 25 months after the surgery, the patient had relapsed.

Conclusions

We report a very rare case of pure H-FLAC. This histology has been considered to predict an extremely poor prognosis; therefore, the elucidation of genetic abnormalities and effective treatment is awaited.