Primary pulmonary adenocarcinoma with intestinal differentiation mimicking metastatic colorectal carcinoma: case report and review of literature

Value of 18F-FDG PET/CT-based radiomics features for differentiating primary lung cancer and solitary lung metastasis in patients with colorectal adenocarcinoma

OBJECTIVE

To investigate the value and applicability of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) radiomics in differentiating primary lung cancer (PLC) from solitary lung metastasis (SLM) in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

This retrospective study included 103 patients with CRC and solitary pulmonary nodules (SPNs). The least absolute shrinkage and selection operator (LASSO) was used to screen for optimal radiomics features and establish a PET/CT radiomics model. PET/CT Visual and complex models (combining radiomics with PET/CT visual features) were developed. The area under the receiver operating characteristic (ROC) curve (AUC) was used to determine the predictive value and diagnostic efficiency of the models.

RESULTS

The AUC of the PET/CT radiomics model for differentiating PLC from SLM was 0.872 (95% CI: 0.806-0.939), which was not different from that of the visual (0.829 [95% CI: 0.749-0.908; p = .352]). However, the AUC of the complex model (0.936 [95% CI:0.892-0.981]) was significantly higher than that of the PET/CT radiomics (p = .005) and visual model (p = .001). The sensitivity (SEN), specificity (SPE), accuracy (ACC), positive predictive value (PPV), and negative predictive value (NPV) of PET/CT radiomics for differentiating PLC from SLM were 0.720, 0.887, 0.806, 0.857, and 0.770, respectively.

CONCLUSION

PET/CT radiomics can effectively distinguish PLC and SLM in patients with CRC and SPNs and guide the implementation of personalized treatment.

Pulmonary Adenocarcinoma with Enteric Differentiation without TTF-1 Expression Is a Very Rare Subtype with Limited Treatment Options and Poor Prognosis

INTRODUCTION

Pulmonary adenocarcinoma with enteric differentiation (PAED) without thyroid transcription factor-1 (TTF-1) expression is an extremely rare variant of lung cancer. Due to its rarity, few clinicopathological and molecular studies have been performed on PAED, particularly in Caucasian patients. Therefore, it is necessary to obtain clinicopathological data of Caucasian PAED patients without TTF-1 expression, their systemic therapy options, and the efficacy of their systemic treatment.

METHODS

We examined the clinicopathological features of 121 cases of TTF-1-negative pulmonary adenocarcinoma at a certified German lung cancer center including 79 cases without a PAED and 42 cases with a PAED, compared these subgroups, and investigated patients' response to chemotherapy and immunotherapy as first-line treatment. By using endoscopy and/or a PET-CT, a primary adenocarcinoma of the digestive tract was excluded in all PAED patients.

RESULTS

A comparison of clinicopathological data of TTF-1-negative PAED and non-PAED patients revealed a significantly lower frequency of high programmed death receptor ligand 1 (PD-L1) expression in PAED resulting in the lack of single-agent immunotherapy (p = 0.032) in this subgroup. Frequencies of an activating Kirsten rat sarcoma viral oncogene homolog (KRAS) gene mutation were high in both groups (46.7% and 50.0%), but G12C gene mutations were seldomly noted (in 6.7% and 18.5% of patients with evaluable data). Median overall survival (OS) was poor in both groups (10 and 12 months). The majority of PAED patients received platinum-based and taxane-containing chemotherapy or chemo-/immunotherapy with an objective response rate (ORR) of 31.6% and a disease control rate of 57.9%. Median progression-free survival (PFS) and OS of PAED patients with systemic therapy were very poor (3.9 months and 5.9 months).

CONCLUSIONS

Caucasian patients with TTF-1 negative PAED have a poor prognosis with a reduced ORR to standard first-line systemic therapy and short survival times (PFS and OS).

Case report: Pathological complete response of pregnancy associated pulmonary enteric adenocarcinoma to chemoradiotherapy

Pulmonary enteric adenocarcinoma (PEAC) is a rare lung adenocarcinoma with morphological features similar to those of primary and metastatic colorectal adenocarcinoma. To date, only a few studies have reported the therapeutic effects of chemoradiotherapy on PEAC. This report describes the case of a 28-year-old woman with pregnancy-related PEAC who presented with left shoulder pain. A superior sulcus tumor was identified in the left thoracic cavity, and the biopsy indicated more than 50% intestinal differentiation components. Moreover, immunohistochemical staining revealed positive CDX2 and CK7 expression. Positron emission tomography-computed tomography, upper endoscopy, colonoscopy, and small intestinal capsule endoscopy revealed no gastrointestinal malignancies. The patient was diagnosed with locally advanced PEAC (clinical stage T4N0M0; stage IIIA). Therefore, the patient was treated with preoperative chemoradiotherapy and underwent gross total resection during surgery. Pathological evaluation of the specimen revealed no residual tumor, indicating that the chemoradiotherapy for PEAC was highly effective. One subsequent brain metastasis was also resected, and the patient has not experienced recurrence in 28 months since this resection and continues to be monitored regularly. This is the first pathologically confirmed report of the use of chemoradiotherapy (carboplatin [CBDCA] and paclitaxel [PTX]) for PEAC and its clinical efficacy. Unlike previous reports, the efficacy of this treatment is attributed to the use of PTX in preoperative chemotherapy and the p21- status of the patient, which may have increased sensitivity to chemoradiation therapy. Therefore, chemoradiotherapy (CBDCA + PTX) may be a viable treatment option for advanced intestinal lung adenocarcinoma.

Case report: Target and immunotherapy of a lung adenocarcinoma with enteric differentiation, EGFR mutation, and high microsatellite instability

Background

Pulmonary enteric adenocarcinoma (PEAC) is a rare histological subtype of non-small-cell lung cancer (NSCLC) with a predominant (>50%) enteric differentiation component. The frequency of high microsatellite instability (MSI-H) is very low in lung cancer. EGFR tyrosine kinase inhibitors and immunotherapy are standard treatment for NSCLC patients, but their effectiveness in lung adenocarcinoma with pulmonary enteric differentiation is unknown.

Case presentation

This report describes a 66-year-old man who was initially diagnosed with metastatic lung adenocarcinoma with EGFR mutation based on pleural fluid. A lung biopsy was obtained after 17 months of first-line icotinib treatment. Histological analysis of biopsy samples and endoscopic examination resulted in a diagnosis of adenocarcinoma with enteric differentiation. Next-generation sequencing of 1,021 genes showed EGFR E19del, T790M, and MSI-H, while immunohistochemical assay showed proficient expression of mismatch repair (MMR) proteins. Consequently, the patient was treated with osimertinib and had a progression-free survival (PFS) of 3 months. His treatment was changed to chemotherapy with/without bevacizumab for 6.5 months. Then, the patient was treated with one cycle of camrelizumab monotherapy and camrelizumab plus chemotherapy, respectively. The tumor continued to grow, and the patient suffered pneumonia, pulmonary fungal infections, and increased hemoptysis. He received gefitinib and everolimus and died 2 months later and had an overall survival of 30 months.

Conclusion

In summary, our case describes a rare pulmonary enteric adenocarcinoma with an EGFR-activating mutation and MSI-H, responding to an EGFR tyrosine kinase inhibitor and poorly benefiting from an immune checkpoint inhibitor.

Primary pulmonary enteric adenocarcinoma presenting as a solitary skull mass

Pulmonary enteric adenocarcinoma (PEAC) is a rare, aggressive variant of lung adenocarcinoma with early metastatic potential. We present the case of a male smoker in his 50s who presented with right-sided numbness, pain and headache. Imaging revealed a destructive skull base mass invading the right sphenoid sinus. Histopathology was consistent with PEAC. The diagnosis was metastatic PEAC with a distant spread to the skull and represents the first case reported in the literature. We present an associated literature review of the clinical presentation, histological features and management of PEAC with skull metastasis. Metastasis should be considered when evaluating any persistent cranial lesion. Diagnosis requires thorough clinical, radiological and pathological assessment. Treatment involves surgical resection, chemoradiation and targeted therapy. Prognosis directly correlates with clinical stage at presentation. This case highlights the importance of careful evaluation of skull lesions, even in patients without known primary malignancy. Early diagnosis and multimodal therapy may improve outcomes.

Clinical presentation and outcome of patients with enteric-type adenocarcinoma of the lung: A pooled analysis of published cases

Enteric-type adenocarcinoma of the lung (lung-ETAC, former pulmonary enteric adenocarcinoma, PEAC) is a rare subtype of non-small cell lung cancer (NSCLC), which shares morphological and immunohistochemical features with lung and colorectal adenocarcinoma. Few data are available on patient prognosis, possible prognostic factors and systemic approach to metastatic disease. We performed a pooled analysis and a systematic review of published lung-ETAC, along with an additional case description. Thirty-one eligible publications were identified, providing data from 126 patients. In the 127 patients overall analyzed, median overall survival (OS) was 56.0 (range 36.7-75.3) months in early-stage patients and 14.0 (range 4.5-23.5) months in those with advanced/metastatic disease. Median disease-free survival (DFS) after radical surgery was 24 (range 22.6-35.1) months. Smoking status (HR 4.304, 95% CI: 1.261-14.693, p = 0.020) and node involvement (HR 1.853, 95% CI: 1.179-2.911, p = 0.007) were the negative independent prognostic factors at multivariate analysis. As regards systemic therapies for advanced cases, no firm conclusions were drawn about the efficacy of lung cancer-oriented chemotherapy regimens as opposed to colon cancer-oriented ones. Molecular analysis of lung-ETAC revealed a relatively high mutational rate, with alterations in several druggable molecular pathways, KRAS and NRAS (31%) were the most frequently mutated oncogenes, followed by ROS1 (15%), RET (13%), BRAF (11%), EGFR (8%) and ALK (6%). Moreover, 3 (15%) out of 20 cases showed DNA mismatch repair deficiency (dMMR). In conclusion, advanced lung-ETAC patients appeared to have a better prognosis compared to other subtypes of NSCLC. Moreover, the mutational rate and microsatellite instability found in lung-ETACs suggest that a significant proportion of these patients could benefit from target therapies and immunotherapy.

A Radiomics Approach on Chest CT Distinguishes Primary Lung Cancer from Solitary Lung Metastasis in Colorectal Cancer Patients

PURPOSE

This study utilized a radiomics approach combined with a machine learning algorithm to distinguish primary lung cancer (LC) from solitary lung metastasis (LM) in colorectal cancer (CRC) patients with a solitary pulmonary nodule (SPN).

MATERIALS AND METHODS

In a retrospective study, 239 patients who underwent chest computerized tomography (CT) at three different institutions between 2011 and 2019 and were diagnosed as primary LC or solitary LM were included. The data from the first institution were divided into training and internal testing datasets. The data from the second and third institutions were used as an external testing dataset. Radiomic features were extracted from the intra and perinodular regions of interest (ROI). After a feature selection process, Support vector machine (SVM) was used to train models for classifying between LC and LM. The performances of the SVM classifiers were evaluated with both the internal and external testing datasets. The performances of the model were compared to those of two radiologists who reviewed the CT images of the testing datasets for the binary prediction of LC versus LM.

RESULTS

The SVM classifier trained with the radiomic features from the intranodular ROI and achieved the sensitivity/specificity of 0.545/0.828 in the internal test dataset, and 0.833/0.964 in the external test dataset, respectively. The SVM classifier trained with the combined radiomic features from the intra- and perinodular ROIs achieved the sensitivity/specificity of 0.545/0.966 in the internal test dataset, and 0.833/1.000 in the external test data set, respectively. Two radiologists demonstrated the sensitivity/specificity of 0.545/0.966 and 0.636/0.828 in the internal test dataset, and 0.917/0.929 and 0.833/0.929 in the external test dataset, which were comparable to the performance of the model trained with the combined radiomics features.

CONCLUSION

Our results suggested that the machine learning classifiers trained using radiomics features of SPN in CRC patients can be used to distinguish the primary LC and the solitary LM with a similar level of performance to radiologists.

A novel diagnostic model for differentiation of lung metastasis from primary lung cancer in patients with colorectal cancer

Objective

This study aimed to evaluate the ¹⁸F-FDG PET/CT in differentiating lung metastasis(LM) from primary lung cancer(LC) in patients with colorectal cancer (CRC).

Methods

A total of 120 CRC patients (80 male, 40 female) who underwent ¹⁸F-FDG PET/CT were included. The diagnosis of primary lung cancer or lung metastasis was based on histopathology The patients were divided into a training cohort and a validation cohort randomized 1:1. Independent risk factors were extracted through the clinical information and ¹⁸F-FDG PET/CT imaging characteristics of patients in the validation cohort, and then a diagnostic model was constructed and a nomograms was made. ROC curve, calibration curve, cutoff, sensitivity, specificity, and accuracy were used to evaluate the prediction performance of the diagnostic model.

Results

One hundred and twenty Indeterminate lung lesions (ILLs) (77 lung metastasis, 43 primary lung cancer) were analyzed. No significant difference in clinical characteristics and imaging features between the training and the validation cohorts (P > 0. 05). Using uni-/multivariate analysis, pleural tags and contour were identified as independent predictors. These independent predictors were used to establish a diagnostic model with areas under the receiver operating characteristic curves (AUCs) of 0.92 and 0.89 in the primary and validation cohorts, respectively. The accuracy rate of the diagnostic model for differentiating LM from LC were higher than that of subjective diagnosis (P < 0.05).

Conclusions

Pleural tags and contour were identified as independent predictors. The diagnostic model of ILLs in patients with CRC could help differentiate between LM and LC.

A pulmonary enteric adenocarcinoma patient harboring a rare EGFR exon 19 P753S mutation: Case report and review

Pulmonary enteric adenocarcinoma (PEAC) is a rare subtype of non–small cell lung cancer (NSCLC), accounting for about 0.6% of all primary lung adenocarcinoma. Although epidermal growth factor receptor (EGFR) mutation is common in primary lung adenocarcinoma, it is rarely reported in PEAC. This case report describes a PEAC patient with co-mutations of EGFR, Kirsten rat sarcoma viral oncogene (KRAS), and TP53, being treated with immunotherapy combined with chemotherapy. A 69-year-old man complained of cough and expectoration with bloody sputum for 2 weeks. The lung-enhanced CT scan showed a massive soft tissue shadow, about 46 × 35 mm in the lower lobe of the right lung. The neoplasm sample in the lower lobe of the right lung was obtained using CT-guided fine-needle aspiration (FNA). Immunohistochemical assays showed that the tumor was positive for CK7, CDX-2, C-MET, and villin. Gastroscopy and rectal colonoscopy had been performed respectively to exclude a diagnosis of colorectal adenocarcinoma. The patient was finally diagnosed with pulmonary intestinal adenocarcinoma. Next-generation sequencing (NGS) analysis showed a rare EGFR exon 19 missense mutation (c.2257C>T, p.P753S), KRAS exon 2 missense mutation (c.35G>T, p.G12V), and TP53 exon 5 missense mutation (c.401T>C, p.F134S). The lung-enhanced CT scan showed that the tumor shrank after four cycles of chemotherapy combined with immunotherapy. We hope that this case report can increase the understanding of this rare type of tumor and provide new molecular indications for diagnosis and individualized treatment. Furthermore, the combination of chemotherapy and immunotherapy seems to be an effective therapy for PEAC. Whether the use of immunotherapy can provide clinical benefits needs to be further explored with more samples in future studies.

Imaging Characteristics and Prognostic Value of Isolated Pulmonary Metastasis from Colorectal Cancer Demonstrated with18F-FDG PET/CT

Objective. Solitary pulmonary lesions (SPNs) in patients with a history of colorectal cancer (CRC) may be attributed to metastatic lung tumors, primary lung cancer, or benign nodules. We aimed to analyze the imaging characteristics of SPNs in CRC patients to differentiate these pulmonary nodules and evaluate the prognostic value of isolated pulmonary metastasis from CRC using 18F-FDG PET/CT. Methods. From January 2013 to January 2021, 62 CRC patients with SPNs demonstrated with 18F-FDG PET/CT were retrospectively enrolled in the present study. We compared the radiological and clinical characteristics of these patients. In addition, survival time and prognostic factors were statistically analyzed using the Kaplan-Meier method and multivariable Cox proportional hazards models. Results. There were 33 cases of isolated lung metastasis, 20 cases of second primary lung cancer (SPLC), and nine cases of benign nodules. The proportion of nodules with a maximal diameter greater than the median value was lower in the isolated lung metastasis group compared with the SPLC group ( $p<0.05$ ), showing polygonal shape, ill-defined margin, pleural indentation, air bronchogram, speculation, and ground-glass opacity. Patients with isolated lung metastasis had a significantly higher maximal diameter of lung lesion, SUVmax of lung lesion, and 18F-FDG uptake compared with the benign nodule group ( $p<0.05$ ). Multivariate analysis revealed that the following two factors were significant independent predictors of PLC: air bronchogram (hazard ratio [HR] =22.327; 95% confidence interval [CI]: 1.910-261.061; $p=0.013$ ) and spiculation (HR =6.148; 95% CI 1.469-25.725; $p=0.013$ ). Initial TNM stage IV (HR =19.831, 95% CI 1.061-370.782; $p=0.046$ ) was extremely associated with a decreased lifespan of CRC patients with isolated lung metastasis. Conclusions. The result showed that CT features, including air bronchogram and spiculated margins, could be used to differentiate SPLC from single isolated lung metastasis in CRC patients. In patients with isolated lung metastasis, primary CRC TNM stage IV was associated with a poorer prognosis, and patients with such conditions might need more care.

Hyperprogressive Disease After Immunotherapy: A Case Report of Pulmonary Enteric Adenocarcinoma

Primary pulmonary enteric adenocarcinoma (PEAC) is a rare invasive adenocarcinoma clinically similar to metastatic colorectal adenocarcinoma (MCRC). Although many studies have addressed the differential diagnosis of PEAC, few have described the treatment of PEAC, especially using immunotherapy. This report describes a 61-year-old man who presented initially with pain in the ribs. Pathological analysis of biopsy samples shows malignant tumors of the right pleura, and next-generation sequencing of 26 genes showed a KRAS gene mutation. Positron emission tomography-computed tomography (PET-CT) found no evidence of gastrointestinal malignancy. Due to multiple metastases, the patient could not undergo radical surgery. The patient was treated with a combination chemotherapy regimen of paclitaxel plus carboplatin, along with sindilizumab immunotherapy, but, after one cycle of treatment, the tumor showed a hyperprogressive state. The patient is still being monitored regularly. These findings indicate that chemotherapy combined with immunotherapy may be ineffective in the treatment of primary PEAC with positive driver genes.

Combination of Pembrolizumab With Platinum-containing Chemotherapy for Pulmonary Enteric Adenocarcinoma

BACKGROUND/AIM

Pulmonary enteric adeno-carcinoma (PEAC) is a rare type of non-small cell lung cancer (NSCLC), for which no established standard treatment exists. Combination therapy with the anti-programmed cell death protein 1 antibody pembrolizumab and platinum-containing chemotherapy is the standard treatment for NSCLC patients, but its effectiveness in PEAC is uncertain.

CASE REPORT

We present a 68-year-old man with chemotherapy-naïve advanced PEAC who responded to a combination of pembrolizumab and platinum-containing chemotherapy.

CONCLUSION

The number of PEAC cases is small, and no clinical trials have been conducted to determine an optimal chemotherapy regimen. In this case, we showed that pembrolizumab combined with platinum-containing chemotherapy might effectively treat PEAC.

Identification of the most specific markers to differentiate primary pulmonary carcinoma from metastatic gastrointestinal carcinoma to the lung

Background

A number of biomarkers have the potential of differentiating between primary lung tumours and secondary lung tumours from the gastrointestinal tract, however, a standardised panel for that purpose does not exist yet. We aimed to identify the smallest panel that is most sensitive and specific at differentiating between primary lung tumours and secondary lung tumours from the gastrointestinal tract.

Methods

A total of 170 samples were collected, including 140 primary and 30 non-primary lung tumours and staining for CK7, Napsin-A, TTF1, CK20, CDX2, and SATB2 was performed via tissue microarray. The data was then analysed using univariate regression models and a combination of multivariate regression models and Receiver Operating Characteristic (ROC) curves.

Results

Univariate regression models confirmed the 6 biomarkers’ ability to independently predict the primary outcome (p < 0.001). Multivariate models of 2-biomarker combinations identified 11 combinations with statistically significant odds ratios (ORs) (p < 0.05), of which TTF1/CDX2 had the highest area under the curve (AUC) (0.983, 0.960–1.000 95% CI). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 75.7, 100, 100, and 37.5% respectively. Multivariate models of 3-biomarker combinations identified 4 combinations with statistically significant ORs (p < 0.05), of which CK7/CK20/SATB2 had the highest AUC (0.965, 0.930–1.000 95% CI). The sensitivity, specificity, PPV, and NPV were 85.1, 100, 100, and 41.7% respectively. Multivariate models of 4-biomarker combinations did not identify any combinations with statistically significant ORs (p < 0.05).

Conclusions

The analysis identified the combination of CK7/CK20/SATB2 to be the smallest panel with the highest sensitivity (85.1%) and specificity (100%) for predicting tumour origin with an ROC AUC of 0.965 (p < 0.001; SE: 0.018, 0.930–1.000 95% CI).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01184-2.

Pulmonary enteric adenocarcinoma

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Synthetically expounded the clinical characteristics of PEAC.

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Systematically described the differentiation of PEAC from primary lung adenocarcinoma and MCRC.

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Found patients with PEAC may have high frequencies of HER2 and MMR mutations.

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Proposed a new conjecture that patients with PEAC might benefit from anti-HER2 therapy and immune checkpoint inhibitors.

Pulmonary enteric adenocarcinoma (PEAC) is an exceptionally rare subtype of non–small cell lung cancer (NSCLC). It is characterized by pathological features similar to those of colorectal adenocarcinoma. Most patients with PEAC have almost no special clinical manifestations, and it is often difficult to differentiate from metastatic colorectal adenocarcinoma (MCRC). As a special type of lung adenocarcinoma, PEAC has unique mutation expression and immune characteristics; its mutation profile shows higher Kirsten rat sarcoma viral oncogene (KRAS), human epidermal growth factor receptor-2 (HER2) , DNA mismatch repair(MMR) mutation rates, and much lower epidermal growth factor receptor (EGFR) rate. So in the future, targeted therapy may tend to be a new light in the treatment of PEAC. As for immunohistochemistry (IHC), CDX-2, villin, and CK7 are significantly positive in PEAC. This review focuses on the pathologic features, immunohistochemical examination, mutation analysis, diagnosis, treatment, and prognosis of PEAC.

Differentiation of primary lung cancer from solitary lung metastasis in patients with colorectal cancer: a retrospective cohort study

Background

This study aimed to evaluate the computed tomography (CT) features of solitary pulmonary nodule (SPN), which can be a non-invasive diagnostic tool to differentiate between primary lung cancer (LC) and solitary lung metastasis (LM) in patients with colorectal cancer (CRC).

Methods

This retrospective study included SPNs resected in CRC patients between January 2011 and December 2019. The diagnosis of primary LC or solitary LM was based on histopathologic report by thoracoscopic wedge resection. Chest CT images were assessed by two thoracic radiologists, and CT features were identified by consensus. Predictive parameters for the discrimination of primary LC from solitary LM were evaluated using multivariate logistic regression analysis.

Results

We analyzed CT data of 199 patients (mean age, 65.95 years; 131 men and 68 women). The clinical characteristic of SPNs suggestive of primary LC rather than solitary LM was clinical stages I–II CRC (P < 0.001, odds ratio [OR] 21.70). The CT features of SPNs indicative of primary LC rather than solitary LM were spiculated margin (quantitative) (P = 0.020, OR 8.34), sub-solid density (quantitative) (P < 0.001, OR 115.56), and presence of an air bronchogram (quantitative) (P = 0.032, OR 5.32).

Conclusions

Quantitative CT features and clinical characteristics of SPNs in patients with CRC could help differentiate between primary LC and solitary LM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02131-7.

Pulmonary enteric adenocarcinoma: a literature review

Pulmonary enteric adenocarcinoma (PEAC) is an extremely rare type of non-small cell lung cancer (NSCLC) with a histologic pattern that mimics metastatic colorectal cancer (MCC). The main clinical symptoms in PEAC patients are dyspnoea, coughing, hemoptysis, and chest and back pain. The first article about PEAC appeared in 1991 in the form of a case report. As a variant of invasive lung carcinoma, only a small number of case reports and clinical research studies have been carried out, and the only one guidance on diagnosis and treatment is the WHO Tumor Classification book. It is important for doctors to distinguish PEAC from MCC to extend survival time and improve the quality of life. We reviewed the existing literature regarding the diagnosis, treatment, and prognosis of PEAC to provide some valuable clinical references.

Pulmonary enteric adenocarcinoma: an overview

Most commonly described as sporadic, pulmonary adenocarcinoma with enteric differentiation (PAED) is a rare variant of invasive lung cancer recently established and recognised by the World Health Organization. This tumour is highly heterogeneous and shares several morphological features with pulmonary and colorectal adenocarcinomas. Our objective is to summarise current research on PAED, focusing on its immunohistochemical and molecular features as potential tools for differential diagnosis from colorectal cancer, as well as prognosis definition and therapeutic choice. PAED exhibits an 'entero-like' pathological morphology in more than half cases, expressing at least one of the typical immunohistochemical markers of enteric differentiation, namely CDX2, CK20 or MUC2. For this reason, this malignancy appears often indistinguishable from a colorectal cancer metastasis, making the differential diagnosis laborious. Although standard diagnostic criteria have not been established yet, in the past few years, a number of approaches have been addressed, aimed at defining specific immunohistochemical and molecular signatures. Based on previously published literature, we have collected and analysed molecular and immunohistochemical data on this rare neoplasm, and have described the state of the art on diagnostic criteria as well as major clinical and therapeutic implications.The analysis of data from 295 patients from 58 published articles allowed us to identify the most represented immunohistochemical and molecular markers, as well as major differences between Asian PAEDs and those diagnosed in European/North American countries. The innovative molecular approaches, exploring driver mutations or new gene alterations, could help to identify rare prognostic factors and guide future tailored therapeutic approaches to this rare neoplasm.

Differential diagnosis of pulmonary enteric adenocarcinoma and metastatic colorectal carcinoma with the assistance of next-generation sequencing and immunohistochemistry

PURPOSE

Pulmonary enteric adenocarcinoma (PEAC), defined as tumors with an enteric component exceeding 50% and a histological morphology similar to colorectal cancer (CRC) and metastatic colorectal carcinoma (MCC), is an extremely rare primary lung adenocarcinoma, which was recently recognized by World Health Organization (WHO). Adenocarcinomas with intestinal differentiation have also been described in other anatomic sites, including paranasal sinuses, extrahepatic biliary tree, uterine and cervix, ovary. The morphologic spectrum and immunohistochemical profiles of PEAC overlap with those of colonic adenocarcinomas, the diagnosis of PEAC remains challenging. Currently, colonoscopy has to be performed to confirm the diagnosis, resulting in low compliance due to its invasiveness. Due to the rareness of PEAC, its molecular signature has not been comprehensively examined.

METHODS

In this study, we investigated the molecular signatures associated with PEAC and its histological counterparts, CRC and MCC using capture-based targeted sequencing.

RESULTS

We revealed that 12/13 (92.31%) PEAC patients harbored mutations in well-established driver genes for non-small cell lung cancer and none of them had mutations unique to CRC. Furthermore, 13/15 (86.7%) of MCC harbored mutations that are frequently seen in CRC.

CONCLUSION

Collectively, our study showed that PEAC, exhibiting a similar mutational profile with NSCLC, showed a distinctive signature from CRC and MCC. Furthermore, we derived a classification model, intergrading both IHC markers and genetic signature, to accurately diagnose PEAC.

Distinctive features of immunostaining and mutational load in primary pulmonary enteric adenocarcinoma: implications for differential diagnosis and immunotherapy

Background

Primary pulmonary enteric adenocarcinoma (PEAC) is an extremely rare variant of invasive lung cancer. It is highly heterogeneous while shares some common morphologic and immunohistochemical features with usual pulmonary adenocarcinoma (PAC) and colorectal adenocarcinoma (CRAC), making the differential diagnosis difficult. At present there are only limited studies about distinctive features of primary PEAC and the results are often inconsistent.

Methods

We retrospectively analyzed total 129 primary PEACs and 50 CRACs that were published since 1991 or diagnosed in our centre. Among them eight typical samples of primary PEACs and usual PACs were detected by targeted exome sequencing.

Results

The combination of CK7⁺/CDX2⁺ acquires high sensitivity (71.3%) and specificity (82%) in differential diagnosis of PEACs from CRAC. The primary PEACs harbor a high incidence of KRAS mutation but almost absent of EGFR mutation. Moreover, compared with usual PACs, the primary PEACs have higher nonsynonymous tumor mutation burden and more frequent MMR mutation.

Conclusions

The combination of CK7⁺/CDX2⁺ immunostaining and the distinctive genetic signatures, including low incidence of sensitivity genes mutations and high tumor mutation burden, is an important supplementary to the clinical differential diagnosis of primary PEACs. Our findings thus have significant implications for development of individualized treatment strategy in these patients.

CK7/CK20 Double-Negative Pulmonary Enteric Adenocarcinoma With Histopathological Evaluation of Transformation Zone Between Enteric Adenocarcinoma and Conventional Pulmonary Adenocarcinoma

We report a rare case of pulmonary enteric adenocarcinoma (PEA) exhibiting a immunohistochemical feature of CK7/CK20 double-negativity by evaluating the transformation zone between PEA and conventional pulmonary adenocarcinoma (CPA). A 75-year-old man was found to have a mass, 40 mm in diameter, in the right lower lobe on chest computed tomography, and underwent right lower lobectomy. Histologically, the tumor was composed of a PEA and CPA component. The dominant PEA component had medium to large complex glands with tall columnar cells with eosinophilic cytoplasm and brush-border. The CPA component comprised small to medium glands with cuboidal cells. Moreover, intermediate glands (INT), which had cuboidal to tall columnar cells, with morphological features between PEA and CPA, was also observed in the transformation area. Immunohistochemically, the PEA component was negative for CK7, CK20, and TTF-1, and positive for CDX2 and SATB2 (weak): the CPA component was negative for CK20, CDX2, and SATB2, and positive for CK7 and TTF-1: the INT were negative for SATB2, with intermingled positive signals for CK7, CK20, TTF-1, and CDX2. The final diagnosis was PEA based on the CPA component and not colorectal carcinoma. To distinguish CK7-negative PEA from metastatic colorectal carcinoma, careful examination for a CPA component is very useful along with clinical information. There are no reports that discuss about process of oncogenesis, de novo sequence or transformation from CPA of PEA. This is the first reported case of CK7/CK20 double-negative PEA, with analysis of the transformation zone between PEA and CPA components.

Clinicopathological, radiographic, and oncogenic features of primary pulmonary enteric adenocarcinoma in comparison with invasive adenocarcinoma in resection specimens

Primary pulmonary enteric adenocarcinoma (PEAC) is a rare subtype of primary lung adenocarcinoma. However, it is not known whether there are any distinctive clinical or molecular features.PEACs were retrospectively identified in 28 patients from July 2014 to June 2016. We compared the clinicopathological, radiographic, and oncogenic characteristics of PEAC and primary pulmonary invasive adenocarcinoma (IAC).A total of 28 PEAC patients and 92 IAC patients were compared. PEAC occurred more frequently in males (P = .008), in older patients (P = .041), in those with larger lesions (P = .001), and in those in a more advanced stage (P = .011). Radiologically, PEAC patients had larger lesions (P = .025) and more solid (P = .006); however, there were no statistically significant differences in lobulation, spiculation, pleural indentation, pleural effusion, and lymphadenopathy between PEAC and IAC. PEAC had higher values of carcinoembryonic antigen (P = .008) and carbohydrate antigen 19-9 (P < .001) than IAC. PEAC had a higher incidence (40% vs 63%, P < .001) of Kristen rat sarcoma viral oncogene homolog (KRAS) mutations and a lower incidence (10.71% vs 3.3%, P < .001) of epidermal growth factor receptor (EGFR) mutations. Villin may be a useful marker in the differential diagnosis of PEAC. KRAS mutations occurred more frequently in PEACs, which are cytokeratin 7-negative (P = .032). EGFR mutation rates were higher in PEACs, which are cytokeratin 20- and caudal type homeobox transcription factor 2-negative (P = .041).PEAC is a rare and heterogeneous nonsmall-cell lung cancer subgroup with distinctive clinicopathological, radiographic, and molecular features. These results need to be further confirmed in future studies.

Combination of cadherin-17 and SATB homeobox 2 serves as potential optimal makers for the differential diagnosis of pulmonary enteric adenocarcinoma and metastatic colorectal adenocarcinoma

Background

Pulmonary enteric adenocarcinoma (PEAC), a rare type of non-small cell lung cancer, has similar histological and immunohistochemical morphology to colorectal adenocarcinoma. Cadherin-17 (CDH17) and SATB homeobox 2 (SATB2) immunoexpression have recently been demonstrated in colorectal adenocarcinoma. In this study, we evaluated the value of CDH17 and SATB2 in the diagnosis of pulmonary enteric adenocarcinoma and metastatic colorectal adenocarcinoma.

Methods

A total of 13 PEAC cases and 27 metastatic colorectal adenocarcinoma cases were enrolled in our cohort study. We analyzed the expressions of CK7, CK20, CDX-2, villin, cadherin-17 (CDH17), and SATB homeobox 2 (SATB2) using immunohistochemistry. Staining intensity and percentage of positive-staining cells were recorded. Sensitivity and specificity values for immunostains, individually and in combination, were computed and compared.

Results

Combining CDH17 and SATB2 resulted in high sensitivity (76.92%) and specificity (100%). In our study, the use of CK7+, napsin A+, TTF-1+, napsin A+TTF-1+ in combination with CDH17-/SATB2- had a higher area under the curve compared to the combination CDH17-/SATB2-. However, no significant differences were observed between the combination CDH17-/SATB2- and other combinations (P>0.05).

Conclusions

In combination, CDH17 and SATB2 serve as potential optimal markers for the differential diagnosis of PEAC and metastatic colorectal adenocarcinoma.

Pulmonary enteric adenocarcinoma with pancreatic metastasis: A case report

Pulmonary enteric adenocarcinoma is a markedly rare pathological type of lung adenocarcinoma. As the pancreas is a relatively uncommon site for metastasis, the present case is even more unusual. A 62-year-old male was admitted to hospital following the identification of masses in the left chest wall, right abdominal wall and right upper limb, but with no respiratory symptoms. Computed tomography (CT) of the chest revealed a lump in the lung and a mass in the left chest wall, and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake by the lumps was increased. An enhanced abdominal CT revealed a hypodense and homogeneous mass on the head of the pancreas, which was slightly enhanced compared with normal pancreatic tissue. In addition, the ¹⁸F-FDG uptake of the lesion was increased and the standardized uptake value (SUV) delayed was not evidently decreased compared with SUVearly. A number of other abnormal metabolic lesions were also identified using positron emission tomography/CT, whereas no abnormal ¹⁸F-FDG uptake was identified in the gastrointestinal organ. Furthermore, rectocolonoscopy was performed to exclude diagnosis of metastatic colorectal adenocarcinoma. The hematoxylin- and eosin-stained smears of the masses in the right lung and left chest demonstrated an enteric pattern, which shared morphological and immunohistochemical (IHC) features with those of colorectal adenocarcinoma. The IHC detection revealed that the lesions in the right lung were positive for cytokeratin 7 (CK7), and negative for CK20 and thyroid transcription factor 1 (TTF-1), and the expression of caudal type homeobox 2 (CDX2) was weakly positive; the masses in the left chest wall were positive for CK7, negative for TTF-1, and CK20 and CDX2 were weakly expressed.

The Clinical Significance of Occult Gastrointestinal Primary Tumours in Metastatic Cancer: A Population Retrospective Cohort Study

Purpose

The purpose of this study was to estimate the incidence of occult gastrointestinal (GI) primary tumours in patients with metastatic cancer of uncertain primary origin and evaluate their influence on treatments and overall survival (OS).

Materials and Methods

We used population heath data from Manitoba, Canada to identify all patients initially diagnosed with metastatic cancer between 2002 and 2011. We defined patients to have “occult” primary tumour if the primary was found at least 6 months after initial diagnosis. Otherwise, we considered primary tumours as “obvious.” We used propensity-score methods to match each patient with occult GI tumour to four patients with obvious GI tumour on all known clinicopathologic features. We compared treatments and 2-year survival data between the two patient groups and assessed treatment effect on OS using Cox regression adjustment.

Results

Eighty-three patients had occult GI primary tumours, accounting for 17.6% of men and 14% of women with metastatic cancer of uncertain primary. A 1:4 matching created a matched group of 332 patients with obvious GI primary tumour. Occult cases compared to the matched group were less likely to receive surgical interventions and targeted biological therapy, and more likely to receive cytotoxic empiric chemotherapeutic agents. Having an occult GI tumour was associated with reduced OS and appeared to be a nonsignificant independent predictor of OS when adjusting for treatment differences.

Conclusion

GI tumours are the most common occult primary tumours in men and the second most common in women. Patients with occult GI primary tumours are potentially being undertreated with available GI site-specific and targeted therapies.

Typing of colon and lung adenocarcinoma by high throughput imaging mass spectrometry

In advanced tumor stages, diagnosis is frequently made from metastatic tumor tissue. In some cases, the identification of the tumor of origin may be difficult by histology alone. In this setting, immunohistochemical and molecular biological methods are often required. In a subset of tumors definite diagnosis cannot be achieved. Thus, additional new diagnostic methods are required for precise tumor subtyping. Mass spectrometric methods are of special interest for the discrimination of different tumor types. We investigated whether it is possible to discern adenocarcinomas of colon and lung using high-throughput imaging mass spectrometry on formalin-fixed paraffin-embedded tissue microarrays. 101 primary adenocarcinoma of the colon and 91 primary adenocarcinoma of the lung were used to train a Linear Discriminant Analysis model. Results were validated on an independent set of 116 colonic and 75 lung adenocarcinomas. In the validation cohort 109 of 116 patients with colonic and 67 of 75 patients with lung adenocarcinomas were correctly classified. The ability to define proteomic profiles capable to discern different tumor types promises a valuable tool in cancer diagnostics and might complement current approaches. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.

MicroRNA profiling of primary pulmonary enteric adenocarcinoma in members from the same family reveals some similarities to pancreatic adenocarcinoma-a step towards personalized therapy

Background

Primary pulmonary enteric adenocarcinoma (PEAC) is defined as a pulmonary adenocarcinoma with a predominant component of intestinal differentiation and tumor cells positive for at least one intestinal marker. The aim of the present study was the molecular and histological characterization of a PEAC from a patient with two other family members affected by similar lung tumors, which has never been reported before.

Findings

We evaluated the molecular characteristics of the proband’s PEAC by using a previously validated 47-microRNA (miRNA) cancer-specific array and a predictive method to estimate tissue-of-origin probabilities. Immunohistochemical (IHC) staining for thyroid transcription factor (TTF-1), napsin A, caudal-related homeobox 2 (CDX2), cytokeratins, and mucins, as well as mutational analyses for epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), and anaplastic lymphoma kinase (ALK) were performed on formalin-fixed, paraffin-embedded (FFPE) tissues.

The occurrence of PEAC in two family members was associated with similar clinicopathological features (age at diagnosis, smoking habit, tumor localization, multiple colonic polyps), histologic findings (TTF-1 negativity and CDX2 positivity), and genetic findings (KRAS (Gly12Asp) mutation, but no EGFR/ALK aberrations). miRNA profiling revealed similarities with non-small cell lung cancer (NSCLC; 75.98 %) and some overlap with pancreatic ductal adenocarcinoma (PDAC; 23.34 %), but not with colorectal cancer (CRC; less than 0.5 %). Notably, these PEACs share key PDAC-associated miRNAs associated with tumor aggressiveness (miR-31*/-126*/-506/-508-3p/-514).

Conclusions

We describe for the first time PEAC in members from the same family, associated with similar clinical and genetic features. miRNA profiling of the PEAC resembled a NSCLC signature, with partial overlap to a PDAC pattern. This could explain its aggressive behavior and therefore help to guide future tailored-therapeutic approaches.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0162-5) contains supplementary material, which is available to authorized users.

Clinicopathological observation of primary lung enteric adenocarcinoma and its response to chemotherapy: A case report and review of the literature

Primary lung enteric adenocarcinoma is a rare type of invasive lung carcinoma. Its morphology and immunohistochemistry are those of colorectal carcinoma, but there is no associated primary colorectal carcinoma. The present study describes the case of a 53-year-old female who presented with an irritating cough and a mass around the right sternoclavicular joint. Comprehensive evaluation revealed involvement of the mediastinum, lungs, right sternoclavicular joint and right kidney. Biopsies from the mediastinal and right sternoclavicular joint tumors showed features of adenocarcinoma. Immunohistochemistry was positive for cytokeratin (CK)20 and caudal type homeobox transcription factor 2, and negative for CK7, thyroid transcription factor-1 and napsin A. Genotypic analysis identified the expression of wild-type epidermal growth factor receptor, Kirsten rat sarcoma viral oncogene homolog, serine/threonine-protein kinase B-Raf and UDP-glucuronosyltransferase 1-1. There was no expression of echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase and a moderate expression of excision repair cross-complementation group 1, ribonucleoside-diphosphate reductase large subunit and tubulin β-3 chain. A strong expression of thymidylate synthase and 677TC genotype expression of methylenetetrahydrofolate reductase was observed. Gastroscopy, enteroscopy, colorectal colonoscopy and positron emission tomography-computed tomography failed to find evidence of a gastrointestinal malignancy and primary lung enteric adenocarcinoma was diagnosed. The presence of multiple metastases did not permit curative surgery. The patient was treated with 3 monthly cycles of the XELOX chemotherapy regimen; the response was poor with progression of supraclavicular lesions. Treatment was switched to the TP regimen for 4 monthly cycles, which resulted in a significant reduction in the size of the lung lesions; however, the supraclavicular lesion responded poorly to the treatment. The patient then received 2 cycles of the FOLFIRI regimen; however, the lung and right supraclavicular lesions progressed, causing increased right upper limb pain. The pain was alleviated by palliative surgery. Following surgery, the DP regimen was employed. Follow-up of the patient remains ongoing. The present findings suggest that the early diagnosis and treatment of primary lung enteric adenocarcinoma is likely to improve patient outcome.

Intra-Alveolar Intestinal Epithelium: A Reappraisal of the So-Called Mucinous Goblet-Cell Rich Carcinoma Apropos of Two Cases With Prolonged Follow-up and Literature Review

Primary pulmonary mucin-rich lesions with abundant goblet cells growing within alveolar spaces are either classified as mucinous adenocarcinoma (previously called mucinous bronchioloalveolar carcinoma) or colloid carcinoma. Some of these lesions display a morphologic pattern characterized by paucicellular discontinuous patches of nonatypical colonic type epithelium attached to alveolar walls without evidence of invasion. Immunohistochemically, these epithelial patches express an intestinal immunophenotype (CD20+, CDX-2+, CK7-, TTF-1-). None of the lesions so far reported with these histological and immunohistochemical characteristics have recurred or metastasized. Herein we describe 2 patients with this type of intra-alveolar mucinous lesions who have been meticulously followed-up for 9 and 14 years, respectively, without evidence of disease progression. Based on their histologic appearance, immunoreactivity, and on the presence of occasional CDX-2 expressing cells in terminal airways adjacent to the lesions, we propose alternative interpretations of the mucin-producing epithelium. More important, a separate provisional category for these lesions is suggested that eliminates their force inclusion as adenocarcinomas.

Intestinal type of lung adenocarcinoma in younger adults

Intestinal type of lung adenocarcinoma (ILADC) was initially described by Tsao and Fraser in 1991. Morphology and immunophenotype of ILADC are the same as in colorectal adenocarcinoma. Rectocolonoscopy must be performed to exclude colorectal origin of adenocarcinoma. Colorectal adenocarcinoma claimed to be genetically similar to an ILADC. Patients. We describe 24- and 26-year-old patients of both genders who went under surgery because of a lung tumor mass detected on CT scan. ILADC was diagnosed on resected lung specimens. According to positivity of Cytokeratin20, CDX-2, and Villin, respectively, and negativity of Cytokeratin7, TTF-1, Napsin-A, SurfactantB, MUC-1, and MUC-2, respectively, ILADC was diagnosed. KRAS mutation was detected in tumor tissue of the male patient. Conclusion. Rectocolonoscopy is the only relevant method for distinguishing the intestinal type of lung adenocarcinoma from metastatic colorectal carcinoma because immunohistochemistry and detection of mutation status are frequently the same in both types of adenocarcinoma. More investigations are needed for further understanding of ILADC in purpose of personalized lung carcinoma therapy particularly introducing detection of mutation status, especially in younger patients.

Diagnosis of lung adenocarcinoma in resected specimens: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

A new lung adenocarcinoma classification has been published by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. This new classification is needed to provide uniform terminology and diagnostic criteria, most especially for bronchioloalveolar carcinoma. It was developed by an international core panel of experts representing all 3 societies with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons.This summary focuses on the aspects of this classification that address resection specimens. The terms bronchioloalveolar carcinoma and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced, such as adenocarcinoma in situ and minimally invasive adenocarcinoma for small solitary adenocarcinomas with either pure lepidic growth (adenocarcinoma in situ) and predominant lepidic growth with invasion of 5 mm or less (minimally invasive adenocarcinoma), to define the condition of patients who will have 100% or near 100% disease-specific survival, respectively, if they undergo complete lesion resection. Adenocarcinoma in situ and minimally invasive adenocarcinoma are usually nonmucinous, but rarely may be mucinous. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous bronchioloalveolar carcinoma), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid, fetal, and enteric adenocarcinoma.It is possible that this classification may impact the next revision of the TNM staging classification, with adjustment of the size T factor according to only the invasive component pathologically in adenocarcinomas with lepidic areas.

Pulmonary enteric adenocarcinoma with villin brush border immunoreactivity: a case report and literature review

Pulmonary enteric adenocarcinoma, a rare histologic type of primary pulmonary adenocarcinoma with only 16 cases reported to date, has to be differentiated from metastatic colorectal carcinoma. Here we report a case of pulmonary enteric adenocarcinoma which shows villin immunoreactivity in the brush border of tumor cells. As a marker for gastrointestinal adenocarcinoma, villin has been rarely found positive like this pattern in pulmonary adenocarcinomas. This case suggests brush border immunoreactivity of villin is possible in some cases of pulmonary enteric adenocarcinomas. We suggest pathological practitioners pay attention to it.

Rare subtypes of adenocarcinoma of the lung

The 1999 WHO classification of adenocarcinoma of the lung and pleural tumors listed five rare variants of adenocarcinoma of the lung: well-differentiated fetal adenocarcinoma, colloid 'mucinous' adenocarcinoma, mucinous cystadenocarcinoma, signet ring adenocarcinoma and clear-cell adenocarcinoma. The International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society developed a multidisciplinary, international classification of lung adenocarcinoma that was published in the February 2011 issue of the journal of Thoracic Oncology. This most current classification lists four rare variants of invasive adenocarcinoma of the lung: invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid adenocarcinoma (retained and expanded), fetal adenocarcinoma (retained) and enteric adenocarcinoma (new). Signet ring adenocarcinoma and clear-cell adenocarcinoma were removed from the list of variants of adenocarcinoma of the lung. Mucinous cystadenocarcinoma was merged into colloid adenocarcinoma. The new 2011 classification also takes into consideration of the amount of tissue sample available according to the two major methods how the tumor is procured: resection specimens versus small biopsy/cytology. Rare variants of invasive adenocarcinoma of the lung will only now be classified from resection specimens where adequate architecture of tumor can be identified.

A case of colorectal cancer with double-activating epidermal growth factor receptor mutations

We describe the case of a 72-year-old woman with locally advanced lung tumor mimicking primary lung cancer. She was diagnosed with rectal cancer at the age of 65 years and was initially treated with platinum-based chemotherapy and thoracic irradiation as a treatment for primary lung cancer. One year later, a thyroid tumor was detected in her right thyroid lobe and was confirmed to have metastasized from rectal cancer based on pathological findings. Therefore, we suspected that she had metachronous double cancers and treated her with conventional chemotherapy for colorectal cancer. However, new life-threatening multiple lung metastases appeared. We treated her with the drug erlotinib because additional genetic analysis against primary lung tumor revealed typical double-activating epidermal growth factor receptor mutations. Histological review by immunostaining concluded that the primary lung tumor was composed of metastatic tumors from rectal cancer. In addition, genetic analysis revealed that the primary rectal cancer contained nearly the same types of double-activating epidermal growth factor receptor mutations as were present in the lung tumor. This is the first report of a case of rectal adenocarcinoma with double-activating epidermal growth factor receptor mutations.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

Primary pulmonary adenocarcinoma with enteric differentiation resembling metastatic colorectal carcinoma: a report of the second case negative for cytokeratin 7

We report the case of a 51-year-old woman with pulmonary adenocarcinoma with enteric differentiation (PAED) that is indistinguishable from metastatic colorectal carcinoma by immunohistochemistry as well as histology. A chest computed tomography scan revealed a 1cm nodule in the right upper lobe and a 3cm mass in the left lower lobe. Initial examination showed no evidence of any other tumor. She underwent partial resection of the right upper lobe and left lower lobectomy. Histopathological examination revealed that both tumors were composed of medium to large complex glands with central necrosis. The tumor cells were cuboidal to tall columnar with eosinophilc cytoplasm, oval nuclei, and brush-border. Immunohistochemical study yielded the following results: tumor cells were diffusely positive for cytokeratin (CK) 20 and CDX-2, and negative for CK7, thyroid transcription factor-1, and Napsin A. MUC2 was partially observed, while MUC5AC was not detected. These findings were strongly indicative of metastatic colorectal carcinoma. However, no primary colorectal cancer was detected in any clinical examination, including fluorine 18-labeled fluorodeoxyglucose-positron emission tomography scan and video capsule endoscopy, and she has not presented with any characteristic symptoms at any follow-up to date, approximately 4 years after operation. From all features, the final diagnosis was primary PAED, suggestive of multifocal primary lung cancer. So far, only 1 case of CK7-negative PAED has been reported. This is the second case of primary PAED resembling metastatic colorectal cancer morphologically and immunohistologically.

Large cell carcinoma of the lung: an endangered species?

This study aims to evaluate large cell carcinomas (LCC) of the lung with a panel of immunohistochemical markers in an attempt to identify tumors belonging to other categories. We analyzed a tissue microarray platform of 101 LCC with a panel of 31 monoclonal antibodies. The tumors were 82 (81.3%) classic LCC, 7 (6.9%) neuroendocrine LCC, 6 (5.9%) lymphoepithelioma-like LCC, 3 (2.9%) basaloid LCC, 2 (2%) clear cell LCC, and 1 (1%) LCC with rhabdoid phenotype. Characteristic classic LCC immunophenotype was loss of staining with CK5/6, CK14 positive in most squamous cell carcinoma (SCC), lack of MOC 31 positive in most adenocarcinomas, and positive immunoreactivity to EGFR, PDGFR-alpha and c-kit. 27 of 82 classic LCC (32.9%) were re-classified as adenocarcinomas, because they coexpressed TTF-1, CK7, and CK19, and were negative for p63. 31 (37.8%) of 82 classic LCC were reclassified as poorly differentiated SCC, based on their immunoreactivity with 34betaE12, p63, thrombomodulin, and CD44v6. 16 (19.5%) of 82 classic LCC correspond to undifferentiated adenosquamous carcinomas, since they displayed conflicting immunostaining for markers of both SCC and adenocarcinomas. The use of 7 immunohistochemical markers, consisting of TTF-1, CK7, CK19, p63, 34betaE12, thrombomodulin, and CD44v6, markedly reduces dramatically to less than 10%, the number of classic LCC by readily identifying cases of poorly differentiated SCCs, adenosquamous carcinoma and adenocarcinomas.

MicroRNA expression differentiates between primary lung tumors and metastases to the lung

For surgical pathologists, distinguishing whether a pulmonary neoplasm is primary or metastatic can be challenging, and current biomarkers do not always aid lung tumor classification. The tissue-associated expression of microRNA likely explains the remarkable finding that many tumors can be classified based solely on their microRNA expression signature. Here we show that microRNAs can serve as biomarkers for lung tumor classification. Using microRNA microarray data generated from 76 formalin-fixed, paraffin-embedded (FFPE) samples of either primary lung cancer or metastatic tumors to the lung, we have identified a set of microRNAs expressed differentially between these two groups. This set includes hsa-miR-182, which was most strongly over-expressed in the lung primary tumors, and hsa-miR-126, which was over-expressed in the metastatic tumors. The differential expression of this set of microRNAs was confirmed using qRT-PCR on a set of 54 samples. In light of our data, microRNA expression should be considered as a potential clinical biomarker for surgical pathologists faced with discerning the tumor type of an inscrutable lung neoplasm.