Case Report: Primary Thoracic Low-Grade Fibromyxoid Sarcoma in a Young Girl Presenting With Mediastinal Mass Syndrome.

Low-grade fibromyxoid sarcomas (LGFMSs) are typically adult-onset tumors that arise from the extremities. Here, we report an exceptional case of primary thoracic LGFMS in an 8-year-old girl that resulted in mediastinal syndrome. In reporting this case, we discuss the clinical challenges, role of molecular profiling and review reported cases of pediatric thoracic LGFMSs.

Ten-Year Experience of Chest Wall Reconstruction: Retrospective Review of a Titanium Plate MatrixRIB™ System.

Chest wall tumor resection can result in a large defect that can pose a challenge in reconstruction in restoring chest wall contour, maintaining respiratory mechanics, and improving cosmesis. Titanium plates were first introduced for treating a traumatic flail chest, which yielded promising results in restoring chest wall stability. Subsequently, the applications of titanium plates in chest wall reconstruction surgery were demonstrated in case reports and series. Our center has adopted this technique for a decade, and patients are actively followed up after operation. Here, we retrospectively analyze our 10-year experience of using titanium plates and other reconstruction approaches for chest wall reconstruction, in terms of clinical outcomes, complications, and reasons for reoperation to determine long-term safety and efficacy. Thirty-eight patients who underwent chest wall resection and reconstruction surgery were identified. Of these, 11 had titanium plate insertion, 11 had patch repair or flap reconstruction, and the remaining 16 had primary closure of defects. Chest wall reconstruction using titanium plate(s) and patch repair (with or without flap reconstruction) was associated with larger chest wall defects and more sternal resections than primary closure. Subgroup analysis also showed that reconstruction by the titanium plate technique was associated with larger chest wall defects than patch repair or flap reconstruction [286.80 cm2 vs. 140.91 cm2 (p = 0.083)]. There was no 30-day hospital mortality. Post-operative arrhythmia was more commonly seen following chest wall reconstruction compared with primary closure (p = 0.041). Furthermore, more wound infections were detected following the use of titanium plate reconstruction compared with the patch repair (with or without flap reconstruction) approach (p = 0.027). In conclusion, the titanium plate system is a safe, effective, and robust approach for chest wall reconstruction surgery, especially in tackling larger defect sizes.

Uniportal video-assisted thoracic surgery for major lung resection is associated with less immunochemokine disturbances than multiportal approach.

Multiportal video-assisted thoracic surgery (VATS) for major lung resection causes less immunochemokine production compared to thoracotomy. Whether uniportal VATS is similarly associated with lower early postoperative circulating levels of immunochemokines compared to multiportal VATS have not been studied. Selected patients who received uniportal or multiportal VATS major lung resection were recruited. Blood samples were collected preoperatively and on postoperative days 1 and 3 for enzyme linked immunosorbent assay of serum levels of Tissue Inhibitor of Metalloproteinase (TIMP)-1, Insulin Growth Factor Binding Protein (IGFBP)-3, and Matrix Metalloproteinase (MMP)-9. A linear mixed-effects models were used to analyze the effects of uniportal VATS on the postoperative circulating chemokine levels. From March 2014 to April 2017, 68 consecutive patients consented for the prospective study and received major lung resection by either uniportal VATS (N = 29) or multiportal VATS (N = 39) were identified. Uniportal VATS major lung resection was associated with lower post-operative levels of TIMP-1 and MMP-9 compared to multiportal VATS after controlling for the effects of the corresponding baseline level and the time of follow-up measurement. No difference was observed for the level of IGFBP-3. Less immunochemokine disturbances was observed after uniportal VATS major lung resection compared to multiportal VATS.

EGFR mutation exists in squamous cell lung carcinoma.

Whether EGFR mutation occurs in lung squamous cell carcinoma (SCC) remains a controversial issue. Although numerous trials have shown positive response to tyrosine kinase inhibitors in SCC, these observations have not been well correlated with presence or absence of EGFR mutation. A complicating issue is that adenosquamous carcinoma, a mimic of SCC, frequently harbours EGFR mutations. We evaluated the EGFR mutation status of 191 cases initially diagnosed as SCC of lung origin in years 2000-2011, and performed a panel of markers including p40, p63, CK5/6, TTF-1, mucicarmine on the tissue microarray or tissue blocks from each case, to ascertain the squamous differentiation of each case. Four cases were found to have EGFR mutations, with three showing typical squamous morphological features and immunohistochemical profile on all available tumour blocks, and one reclassified as adenosquamous carcinoma. Mixed responses were noted for two of the patients with EGFR-mutated SCC treated with tyrosine kinase inhibitors. In conclusion, we report that a small subset of rigorously proven SCC harbours EGFR mutation. It also appears in our cohort that EGFR-mutated tumours, in the context of SCC, may have relatively poor response to tyrosine kinase inhibitors.

Ambient fine particulate matter inhibits 15-lipoxygenases to promote lung carcinogenesis.

BACKGROUND: Epidemiological observations have demonstrated that ambient fine particulate matter with dp < 2.5 µm (PM2.5) as the major factor responsible for the increasing incidence of lung cancer in never-smokers. However, there are very limited experimental data to support the association of PM2.5 with lung carcinogenesis and to compare PM2.5 with smoking carcinogens. METHODS: To study whether PM2.5 can contribute to lung tumorigenesis in a way similar to smoking carcinogen 4-methylnitrosamino-l-3-pyridyl-butanone (NNK) via 15-lipoxygenases (15-LOXs) reduction, normal lung epithelial cells and cancer cells were treated with NNK or PM2.5 and then epigenetically and post-translationally examined the cellular and molecular profiles of the cells. The data were verified in lung cancer samples and a mouse lung tumor model. RESULTS: We found that similar to smoking carcinogen NNK, PM2.5 significantly enhanced cell proliferation, migration and invasion, but reduced the levels of 15-lipoxygenases-1 (15-LOX1) and 15-lipoxygenases-2 (15-LOX2), both of which were also obviously decreased in lung cancer tissues. 15-LOX1/15-LOX2 overexpression inhibited the oncogenic cell functions induced by PM2.5/NNK. The tumor formation and growth were significantly higher/faster in mice implanted with PM2.5- or NNK-treated NCI-H23 cells, accompanied with a reduction of 15-LOX1/15-LOX2. Moreover, 15-LOX1 expression was epigenetically regulated at methylation level by PM2.5/NNK, while both 15-LOX1 and 15-LOX2 could be significantly inhibited by a set of PM2.5/NNK-mediated microRNAs. CONCLUSION: Collectively, PM2.5 can function as the smoking carcinogen NNK to induce lung tumorigenesis by inhibiting 15-LOX1/15-LOX2.

Evidence for surgical resections in oligometastatic lung cancer.

With the advent of advanced technology in performing diagnostics for lung cancer, an incremental increase in the number of patients with oligometastatic disease is currently being managed with intent to cure. As treatment of selected types of patients with oligometastasis show favourable outcomes, the past notion of managing these patients palliatively is fast becoming extinct. Selection of patients based on established criterion together with surgical metastasectomy combined with multiple ablative techniques with or without systemic chemotherapy offers a reasonable rate of treatment success which provides basis for treating such patient population. As more evidence becomes available to suggest that the oligometastatic state of lung cancer does exist, and are potentially curable, a better understanding of the condition is necessary for clinicians, and surgeons to provide optimal care. In this review we present some of the clinical basis which may cause a paradigm shift in management of patients with oligometastatic lung disease.

The Landscape of Actionable Molecular Alterations in Immunomarker-Defined Large-Cell Carcinoma of the Lung.

INTRODUCTION: Patients with pulmonary large-cell carcinoma (LCC) have poor prognosis and limited treatment options. The identification of clinically actionable molecular alterations helps to guide personalized cancer treatment decisions. PATIENTS AND METHODS: A consecutive cohort of 789 resected NSCLC cases were reviewed. Fifty-nine NSCLC cases lacking morphologic differentiation, accounting for 7.5% of all resected NSCLCs, were identified and further characterized by immunohistochemistry according to the 2015 WHO lung tumor classification. Molecular alterations were investigated by multiple technologies including target capture sequencing, immunohistochemistry, and fluorescence in situ hybridizations. RESULTS: Of 59 NSCLC cases lacking morphologic differentiation, 20 (33.9%) were reclassified as adenocarcinoma (LCC-AD), 14 (23.7%) as squamous cell carcinoma (LCC-SqCC), and 25 (42.4%) as LCC-Null. Approximately 92% of LCC-Null, 95% of LCC-AD, and 86% of LCC-SqCC harbored clinically relevant alterations. Alterations characteristic of adenocarcinoma (EGFR, KRAS, ALK receptor tyrosine kinase [ALK], ROS1, and serine/threonine kinase 11 [STK11]) were detected in the LCC-AD subgroup but not in LCC-SqCC, whereas squamous-lineage alterations (phosphatidylinositol-4,5-biphosphate 3-kinase catalytic subunit alpha [PIK3CA], SRY-box 2 [SOX2], fibroblast growth factor receptor 1 [FGFR1], and AKT1) were detected in the LCC-SqCC subgroup but not in the LCC-AD group. Although some LCC-Null tumors displayed a genetic profile similar to either adenocarcinoma or squamous-cell carcinoma, more than half of the LCC-Null group were completely devoid of recognizable lineage-specific genetic profiles. High programmed death ligand 1 expression and high frequency of cell cycle regulatory gene alterations were found in the LCC-Null group offering alternative options of targeted therapy. CONCLUSIONS: This comprehensive molecular study provided further insight into the genetic architecture of LCC. The presence of clinically actionable alterations in a majority of the tumors allowed personalized treatment to emerge.

Video-assisted thoracic surgery for tiny pulmonary nodules with real-time image guidance in the hybrid theatre: the initial experience.

BACKGROUND: Localization of tiny lung nodules during video-assisted thoracic surgery (VATS) resection can be challenging. Real-time image-guided hookwire localization of the target lesions immediately followed by VATS lung resection in the hybrid operating theatre setting is an emerging approach. METHODS: We retrospectively reviewed our experience with this form of hybrid operating theatre image-guided VATS (iVATS) for lung nodules 1.5 cm or less, or soft in consistency. These patients were compared with matched cohort who received standard hookwire localization in the radiology department. RESULTS: From February 2014 to September 2017, lung nodules of indeterminate nature in 32 consecutive patients with mean size 9.1±4.6 mm underwent iVATS. All were accurately localized by hookwire and successfully resected. There was no postoperative mortality. There were 21 (66%) malignant lesions, all with adequate resection margins. Major outcomes were compared with a comparable cohort of 8 patients who received standard hookwire localization and VATS (sVATS) performed at separate departments operation suites. sVATS groups has significantly longer 'at-risk' period for pneumothorax progression and hookwire dislodgement (109.5±57.1 minutes for sVATS vs. 41.1±15.0 minutes for iVATS, P=0.011), and a higher risk of hookwire dislodgement (25% for sVATS vs. 0 for iVATS, P=0.036). CONCLUSIONS: Real-time image-guided hookwire localization in the hybrid theatre setting is an effective facilitator of VATS resection of tiny lung nodules in selected patients, and may have added advantages in terms of safety and localization accuracy over the conventional sVATS method.

Assessment of programmed cell death ligand-1 expression by 4 diagnostic assays and its clinicopathological correlation in a large cohort of surgical resected non-small cell lung carcinoma.

Immune checkpoint blockade targeting the PD-1/PD-L1 axis has recently demonstrated efficacy and promise in cancer treatment. Appropriate biomarker selection is therefore essential for improving treatment efficacy. However, the establishment of PD-L1 assay in pathology laboratories is complicated by the presence of multiple testing platforms using different scoring systems. Here we assessed the PD-L1 expression in 713 consecutive non-small cell lung carcinomas by four commercially available PD-L1 immunohistochemical assays, namely, 22C3, 28-8, SP142 and SP263. The analytical performances of the four assays and diagnostic performances across clinically relevant cutoffs were evaluated. The prevalence of PD-L1 (22C3) expression was 21% with a ≥50% cutoff and 56% with a ≥1% cutoff. High PD-L1 expression (using a ≥50% cutoff) was significantly associated with male sex (P = 0.001), ever smoking history (P < 0.001), squamous cell carcinoma (P = 0.001), large cell carcinoma (P < 0.001), lymphoepithelioma-like carcinoma (P = 0.006), sarcomatoid carcinoma (P < 0.001), mutant KRAS (P = 0.005) and wild-type EGFR (P = 0.003). Elevated PD-L1 expression was also significantly associated with shorter survival in patients with adenocarcinoma (log-rank P = 0.026) and remained an independent prognostic factor by multivariable analysis. Among the four assays, 22C3, 28-8 and SP263 were highly concordant for tumor cell scoring. With a cutoff of ≥50% (i.e., the threshold for first-line patient selection), inter-rater agreement was high among the three assays with percentage agreement >97%. In conclusion, three PD-L1 assays showed good analytical performance and a high agreement with each other, but not all cases were correctly classified using the same clinical cutoff. Further studies comparing the predictive value of these assays are required to address the interchangeability of these assays for clinical use.

Multi-dimensional printing in thoracic surgery: current and future applications.

Three-dimensional (3D) printing has been gaining much attention in the medical field in recent years. At present, 3D printing most commonly contributes in pre-operative surgical planning of complicated surgery. It is also utilized for producing personalized prosthesis, well demonstrated by the customized rib cage, vertebral body models and customized airway splints. With on-going research and development, it will likely play an increasingly important role across the surgical fields. This article reviews current application of 3D printing in thoracic surgery and also provides a brief overview on the extended and updated use of 3D printing in bioprinting and 4D printing.

FOXP3 promotes tumor growth and metastasis by activating Wnt/ß-catenin signaling pathway and EMT in non-small cell lung cancer.

BACKGROUND: The role of cancer cell FOXP3 in tumorigenesis is conflicting. We aimed to study FOXP3 expression and regulation, function and clinical implication in human non-small cell lung cancer (NSCLC). METHODS: One hundred and six patients with histologically-confirmed NSCLC who underwent surgery were recruited for the study. Tumor samples and NSCLC cell lines were used to examine FOXP3 and its related molecules. Various cell functions related to tumorigenesis were performed. In vivo mouse tumor xenograft was used to confirm the in vitro results. RESULTS: NSCLC patients with the high level of FOXP3 had a significant decrease in overall survival and recurrence-free survival. FOXP3 overexpression significantly induced cell proliferation, migration, and invasion, whereas its inhibition impaired its oncogenic function. In vivo studies confirmed that FOXP3 promoted tumor growth and metastasis. The ectopic expression of FOXP3 induced epithelial-mesenchymal transition (EMT) with downregulation of E-cadherin and upregulation of N-cadherin, vimentin, snail, slug, and MMP9. The oncogenic effects by FOXP3 could be attributed to FOX3-mediated activation of Wnt/ß-catenin signaling, as FOXP3 increased luciferase activity of Topflash reporter and upregulated Wnt signaling target genes including c-Myc and Cyclin D1 in NSCLC cells. Co-immunoprecipitation results further indicated that FOXP3 could physically interacted with ß-catenin and TCF4 to enhance the functions of ß-catenin and TCF4, inducing transcription of Wnt target genes to promote cell proliferation, invasion and EMT induction. CONCLUSIONS: FOXP3 can act as a co-activator to facilitate the Wnt-b-catenin signaling pathway, inducing EMT and tumor growth and metastasis in NSCLC.

Penetrating thoracic injury with retained foreign body: can video-assisted thoracic surgery take up the leading role in acute management?

Video-assisted thoracic surgery (VATS) is widely adopted in acute management of patient with thoracic trauma, but its use in penetrating thoracic injuries with retained foreign bodies were rarely reported. We described three of such cases using VATS as the first line approach. Identification of injuries, control of bleeders, clot evacuation, resection of damaged lung parenchyma and safe retrieval of foreign bodies were all performed via complete VATS within short operative time. Patient were uneventfully discharged during early post-operative period. We suggest that, for haemodynamically stable patients, VATS offers a safe and minimally-invasive alternative to conventional thoracotomy for penetrating thoracic injury with retained foreign bodies.

Tumorigenesis of smoking carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone is related to its ability to stimulate thromboxane synthase and enhance stemness of non-small cell lung cancer stem cells.

Lung cancer stem cells (LCSCs) play a critical role in lung cancer development, however, it is unknown whether thromboxane synthase (TXS) plays a role in the maintenance of LCSCs stemness. This study aimed to determine the in vivo role of TXS in lung cancer induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a smoking carcinogen. Results showed that ozagrel, a TXS blocker, suppressed NNK-induced lung tumors in mice. The expressions of CD133 and ALDH1A1 were positively associated with TXS. Similar results were observed in human NSCLC tumor samples. NNK significantly stimulated TXS and enhanced the generation of LCSCs, evident by the upregulation of CD133 and ALDH1A1 expression, and the increase in the number and size of tumor spheres. NNK also promoted the expression of LCSC-related molecules including ß-catenin and Nanog. All these NNK-mediated effects could be offset by ozagrel. In the colony formation assay, NNK increased whereas ozagrel decreased the number of colonies. Collectively, LCSCs and TXS participate in NNK-induced lung cancer. Our data suggest that TXS is a promising therapeutic target as it is a key molecular in NNK-mediated stemness of LCSCs.

Antineoplastic effects of 15(S)-hydroxyeicosatetraenoic acid and 13-S-hydroxyoctadecadienoic acid in non-small cell lung cancer.

BACKGROUND: Previous studies have shown that the levels of 15-lipoxygenase 1 (15-LOX-1) and 15-LOX-2 as well as their metabolites 13-S-hydroxyoctadecadienoic acid (13(S)-HODE) and 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) are significantly reduced in smokers with non-small cell lung carcinoma (NSCLC). Furthermore, animal model experiments have indicated that the reduction of these molecules occurs before the establishment of cigarette smoking carcinogen-induced lung tumors, and this suggests roles in lung tumorigenesis. However, the functions of these molecules remain unknown in NSCLC. METHODS: NSCLC cells were treated with exogenous 13(S)-HODE and 15(S)-HETE, and then the ways in which they affected cell function were examined. 15-LOX-1 and 15-LOX-2 were also overexpressed in tumor cells to restore these 2 enzymes to generate endogenous 13(S)-HODE and 15(S)-HETE before cell function was assessed. RESULTS: The application of exogenous 13(S)-HODE and 15(S)-HETE significantly enhanced the activity of peroxisome proliferator-activated receptor γ (PPARγ), inhibited cell proliferation, induced apoptosis, and activated caspases 9 and 3. The overexpression of 15-LOX-1 and 15-LOX-2 obviously promoted the endogenous levels of 13(S)-HODE and 15(S)-HETE, which were demonstrated to be more effective in the inhibition of NSCLC. CONCLUSIONS: This study has demonstrated that exogenous or endogenous 13(S)-HODE and 15(S)-HETE can functionally inhibit NSCLC, likely by activating PPARγ. The restoration of 15-LOX activity to increase the production of endogenous 15(S)-HETE and 13(S)-HODE may offer a novel research direction for molecular targeting treatment of smoking-related NSCLC. This strategy can potentially avoid side effects associated with the application of synthetic PPARγ ligands.

Alveolar rhabdomyosarcoma of the anterior mediastinum with vessel invasion in a 4-month-old boy: a case report.

INTRODUCTION: Alveolar rhabdomyosarcomas of the mediastinum in children are rarely reported. Multimodality therapy including chemotherapy, surgery and radiotherapy make up the backbone of the treatment of childhood rhabdomyosarcomas. Complete resection whenever achievable is an important prognostic factor. However, complete resection of tumors in the mediastinum often poses a unique challenge to thoracic surgeons due to their close proximity to important neurovascular structures. Complete resection may not always be possible and judicious peri-operative planning and preparation are required to avoid creating unnecessary surgical morbidities resulting in delay of adjuvant therapy. CASE PRESENTATION: A 4-month-old Chinese baby boy was presented to our hospital with stridor, shortness of breath and episodes of cyanosis. Imaging studies found an anterior mediastinal mass compressing the trachea and other neurovascular structures and he was diagnosed to have alveolar rhabdomyosarcoma. Our patient received upfront chemotherapy and subsequently open resection of the mass was attempted via median sternotomy. Intraoperatively, the mass had invaded into the great vessels, precluding a complete resection. Debulking surgery was performed instead and our patient received timely postoperative chemoradiotherapy. CONCLUSIONS: We report a rare case of childhood alveolar rhabdomyosarcoma of the mediastinum with vascular invasion treated with chemoradiotherapy and debulking surgery. Complete resection was not possible due to the close proximity to the great vessels. Different surgical approaches to the mediastinum have been reported in adults and children alike. Regardless of the surgical access, the treatment of childhood rhabdomyosarcomas should be individualized, with careful balance between surgical clearance and surgical morbidity.

Estrogen receptor alpha promotes smoking-carcinogen-induced lung carcinogenesis via cytochrome P450 1B1.

UNLABELLED: Smoking carcinogen N-nitrosamines such as 4-methylnitrosamino-l-3-pyridyl-butanone (NNK) require metabolic activation to exert their genotoxicity. The first activation step is mainly catalyzed by cytochrome P450 (CYP) family. Estrogen receptor α (ERα) plays a role in lung pathology. The association between them is unknown. In this study, we explored the relationship and function of CYP1B1 and ERα in NNK-induced lung tumorigenesis. CYP1B1 and ERα expression was analyzed in human lung cancer tissues and NNK-induced lung tumor of A/J mice. Cell lines NCI-H23 and NCI-H460 were employed to further study the responsible mechanisms using various cellular and molecular approaches. Our in vivo experiments demonstrated that CYP1B1 and ERα were over-expressed at the early stage of NNK-induced lung tumorigenesis. Microarray analysis found that ERα was involved in the extracellular-signal-regulated kinase (ERK)/MAPK pathway. NNK activated RAS/ERK/AP1 as it remarkably increased the levels of p-ERK, c-Fos, and c-Jun but inhibited multiple negative regulators of Ras/ERK/AP1, Pdcd4, Spry1, Spry2, and Btg2 through up-regulating miR-21. Both CYP1B1 siRNA and ERK-specific inhibitor U0126 suppressed NNK-mediated ERα up-regulation, suggesting that ERα was downstream of CYP1B1 and ERK. ERK inactivation led to the accumulation of CYP1B1, indicating that CYP1B1 was upstream of ERK activation. Inhibition of ERK or ERα decreased NNK-induced cell proliferation. Blockage of CYP1B1 or ERα induced apoptosis of lung cancer cells. Collectively, NNK-mediated ERα induction is via CYP1B1 and ERK and contributes to the lung carcinogenesis. The inhibition of CYP1B1, ERK, or ERα may arrest the lung cancer cell growth, implicating a pivotal strategy for the treatment of lung cancer. KEY MESSAGES: Smoking carcinogen NNK requires metabolic activation to exert their genotoxicity. CYP1B1 is the enzyme to catalyze NNK. NNK activates CYP1B1 and ERK to induce ERα. Inhibition of CYP1B1, ERK, or ERα arrests the lung cancer cell growth.

Profiling of Oncogenic Driver Events in Lung Adenocarcinoma Revealed MET Mutation as Independent Prognostic Factor.

INTRODUCTION: Oncogenic driver mutations activating receptor tyrosine kinase pathways are promising predictive markers for targeted treatment. We investigated the mutation profile of an updated driver events list on receptor tyrosine kinase/RAS/PI3K axis and the clinicopathologic implications in a cohort of never-smoker predominated Chinese lung adenocarcinoma. METHODS: We tested 154 lung adenocarcinomas and adenosquamous carcinomas for EGFR, KRAS, HER2, BRAF, PIK3CA, MET, NRAS, MAP2K1, and RIT1 mutations by polymerase chain reaction-direct sequencing. MET amplification and ALK and ROS1 translocations were assessed by fluorescent in situ hybridizations. MET and thyroid transcription factor-1 protein expressions were investigated by immunohistochemistry. RESULTS: Seventy percent of lung adenocarcinomas carried actionable driver events. Alterations on EGFR (43%), KRAS (11.4%), ALK (6%), and MET (5.4%) were frequently found. ROS1 translocation and mutations involving BRAF, HER2, NRAS, and PIK3CA were also detected. No mutation was observed in RIT1 and MAP2K1. Patients with EGFR mutations had a favorable prognosis, whereas those with MET mutations had poorer overall survival. Multivariate analysis further demonstrated that MET mutation was an independent prognostic factor. Although MET protein expression was detected in 65% of lung adenocarcinoma, only 10% of the MET-immunohistochemistry positive tumors harbor MET DNA alterations that drove protein overexpression. Appropriate predictive biomarker is essential for selecting patients who might benefit from specific targeted therapy. CONCLUSION: Actionable driver events can be detected in two thirds of lung adenocarcinoma. MET DNA alterations define a subset of patients with aggressive diseases that might potentially benefit from anti-MET targeted therapy. High negative predictive values of thyroid transcription factor-1 and MET expression suggest potential roles as surrogate markers for EGFR and/or MET mutations.

Mediastinal follicular dendritic cell sarcoma with paraneoplastic pemphigus.

Follicular dendritic cell sarcoma is a rare neoplasm of immune accessory cells. It occurs primarily in lymph nodes. Occurrences in the mediastinum are rarely reported. Diagnosis and management of follicular dendritic cell sarcoma remain unclear, and it is an under-recognized clinical entity. Only a few cases of paraneoplastic pemphigus as the first presentation of follicular dendritic cell sarcoma have been reported. We report an unusual case of follicular dendritic cell sarcoma of the anterior mediastinum, presenting as paraneoplastic pemphigus in a 62-year-old man. Typical histological features confirmed the diagnosis of follicular dendritic cell sarcoma, and surgical resection was successfully performed.