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Background: The latest immunotherapy, used in the treatment of non-small cell lung cancer (NSCLC), uses monoclonal antibodies directed against programmed death ligand 1 (PD-L1) to inhibit its interaction with the PD-1 receptor. Elevated levels of PD-L1 expression were observed on NSCLC cells. The association between PD-L1 expression and clinicopathological features is still unclear. Therefore, we examined this relationship and also compare PD-L1 expression levels with Ki-67, p63 and TTF-1. Methods: 866 samples of NSCLCs were used to prepare tissue microarrays (TMAs) on which immunohistochemical (IHC) reactions were performed. Changes in the level of CD274 (PD-L1) gene expression in 62 NSCLC tumors were tested in relation to 14 normal lung tissues by real-time PCR reactions (RT-PCR). Results: PD-L1 expression was observed in 32.6% of NSCLCs. PD-L1 expression was increased in higher malignancy grades (G) (p < 0.0001) and in higher lymph node status (pN) (p = 0.0428). The patients with low PD-L1 expression had longer overall survival compared to the group with high expression (p = 0.0332) in adenocarcinoma (AC) only. Conclusions: PD-L1 expression seems to be associated with increased tumor proliferation and aggressiveness as well as shorter patient survival in NSCLC, predominantly in the AC group.

Lung cancer is the leading cause of cancer-related deaths worldwide, with lung adenocarcinoma representing the most common lung cancer subtype. Among all lung adenocarcinomas, the most prevalent subset develops via tumorigenesis and progression from atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to minimally invasive adenocarcinoma (MIA), to overt invasive adenocarcinoma with a lepidic pattern. This stepwise development is supported by the clinicopathological and molecular characteristics of these tumors. In the 2015 World Health Organization classification, AAH and AIS are both defined as preinvasive lesions, whereas MIA is identified as an early invasive adenocarcinoma that is not expected to recur if removed completely. Recent studies have examined the molecular features of lung adenocarcinoma tumorigenesis and progression. EGFR-mutated adenocarcinoma frequently develops via the multistep progression. Oncogene-induced senescence appears to decrease the frequency of the multistep progression in KRAS- or BRAF-mutated adenocarcinoma, whose tumor evolution may be associated with epigenetic alterations and kinase-inactive mutations. This review summarizes the current knowledge of tumorigenesis and tumor progression in early lung adenocarcinoma, with special focus on its clinicopathological characteristics and their associations with driver mutations (EGFR, KRAS, and BRAF) as well as on its molecular pathogenesis and progression.

Thyroid transcription factor 1 (TTF-1) immunohistochemistry (IHC) is routinely used for the distinction of primary pulmonary adenocarcinomas. However, TTF-1 can also occur in other malignancies. A tissue microarray containing 17,772 samples from 152 different tumor types was analyzed. Napsin-A, CK20, SATB2, FABP1, and Villin-1 IHC data were available from previous studies. TTF-1 staining was seen in 82 of 152 tumor categories including thyroidal cancers (19–100%), adenocarcinomas (94%), neuroendocrine tumors (67%) of the lung, small cell neuroendocrine carcinomas (71–80%), mesenchymal tumors (up to 42%), and thymomas (39%). Comparative analysis of TTF-1 and Napsin-A revealed a sensitivity/specificity of 94%/86% (TTF-1), 87%/98% (Napsin-A), and 85%/99.1% (TTF-1 and Napsin-A) for the distinction of pulmonary adenocarcinomas. Combined analysis of TTF-1 and enteric markers revealed a positivity for TTF-1 and at least one enteric marker in 22% of pulmonary adenocarcinomas but also a TTF-1 positivity in 6% of colorectal, 2% of pancreatic, and 3% of gastric adenocarcinomas. TTF-1 is a marker of high sensitivity but insufficient specificity for pulmonary adenocarcinomas. A small fraction of TTF-1-positive gastrointestinal adenocarcinomas represents a pitfall mimicking enteric-type pulmonary adenocarcinoma. Combined analysis of TTF-1 and Napsin-A improves the specificity of pulmonary adenocarcinoma diagnosis.

PurposeEndometrial mesonephric-like adenocarcinoma (ML-AC) represents a recently recognized subtype of endometrial adenocarcinoma (AC) associated with a subtle immunophenotype with a characteristic KRAS-mutation. Detailed clinico-pathologic analyses and prognostic data on ML-AC are limited.MethodsWe report a series of four cases with histopathological, immunohistochemical, and molecular analyses. These cases as well as the data of previously published cases were reviewed for clinico-pathologic variables and clinical follow-up information.ResultsForty cases of ML-AC were identified. ML-AC represents about 1% of all endometrial carcinomas. Similar to other types of endometrial AC, vaginal bleeding was the leading presenting symptom, and the mean age was 60.0 years (range 31–91). More than a half of the patients presented with locally advanced disease (≥ FIGO stage II) at time of diagnosis, developed a recurrence or died of the disease within a mean follow-up period of 24.7 months (range 3–144.5 months). The most common site of distant disease was pulmonary involvement. Microscopically, ML-ACs present with mixed morphology and show a co-expression of so-called mesonephric and Müllerian markers, suggesting a Müllerian origin of the tumors. Immunostaining for PD-L1 was negative in all tested cases, using different antibodies against PD-L1. Retained staining for mismatch repair proteins on immunohistochemistry and a POLE-mutation suggest a copy number low phenotype within the molecular classification of endometrial carcinomas. Almost all cases showed a KRAS-mutation at codon 12 (mostly G12V).ConclusionUterine ML-AC represents a distinct subtype of invasive endometrial AC, associated with KRAS-mutations and characteristic immunohistochemical findings. Clinically, ML-AC may show an aggressive behavior with a high rate of recurrent disease and a substantial risk for distant metastatic disease, especially to the lungs.

Immunohistochemistry is increasingly utilized to differentiate lung adenocarcinoma and squamous cell carcinoma. However, detailed analysis of coexpression profiles of commonly used markers in large series of whole-tissue sections is lacking. Furthermore, the optimal diagnostic algorithm, particularly the minimal-marker combination, is not firmly established. We therefore studied whole-tissue sections of resected adenocarcinoma and squamous cell carcinoma ( n =315) with markers commonly used to identify adenocarcinoma (TTF-1) and squamous cell carcinoma (p63, CK5/6, 34 β E12), and prospectively validated the devised algorithm in morphologically unclassifiable small biopsy/cytology specimens ( n =38). Analysis of whole-tissue sections showed that squamous cell carcinoma had a highly consistent immunoprofile (TTF-1-negative and p63/CK5/6/34 β E12-diffuse) with only rare variation. In contrast, adenocarcinoma showed significant immunoheterogenetity for all ‘squamous markers’ (p63 (32%), CK5/6 (18%), 34 β E12 (82%)) and TTF-1 (89%). As a single marker, only diffuse TTF-1 was specific for adenocarcinoma whereas none of the ‘squamous markers,’ even if diffuse, were entirely specific for squamous cell carcinoma. In contrast, coexpression profiles of TTF-1/p63 had only minimal overlap between adenocarcinoma and squamous cell carcinoma, and there was no overlap if CK5/6 was added as a third marker. An algorithm was devised in which TTF-1/p63 were used as the first-line panel, and CK5/6 was added for rare indeterminate cases. Prospective validation of this algorithm in small specimens showed 100% accuracy of adenocarcinoma vs squamous cell carcinoma prediction as determined by subsequent resection. In conclusion, although reactivity for ‘squamous markers’ is common in lung adenocarcinoma, a two-marker panel of TTF-1/p63 is sufficient for subtyping of the majority of tumors as adenocarcinomas vs squamous cell carcinoma, and addition of CK5/6 is needed in only a small subset of cases. This simple algorithm achieves excellent accuracy in small specimens while conserving the tissue for potential predictive marker testing, which is now an essential consideration in advanced lung cancer specimens.

Chordoid glioma is a rare well-circumscribed glial neoplasm arising in adults and predominantly affects females. Tanycytes of the third ventricle have been proposed as the cell of origin owing to its location. It is characterized by chordoid features with myxoid and inflammatory stroma and recurrent missense mutation. We present two cases (30-year-old female and 45-year-old male) with similar complaints of behavioral change and headache. Midline suprasellar homogeneously enhancing mass was seen on contrast-enhanced magnetic resonance imaging. Histopathology and immunohistochemistry was characteristic of chordoid glioma with cords and clusters of epithelioid cells arranged in a solid pattern. There were variable amounts of myxoid stroma and lymphoplasmacytic infiltrate. No mitosis, necrosis, or brain invasion was noted. The cells expressed strong diffuse positivity for glial fibrillary acid protein (GFAP) and weak nuclear thyroid transcription factor (TTF-1). Epithelial membrane antigen (EMA)and brachyury were negative. Subsequently, the lady underwent gross total excision and died soon after the operation. The male patient received radiotherapy and is currently doing well after 6 months of follow-up. The rare occurrence as well as the radiological and morphological overlaps in chordoid gliomas make them a true masquerader. Combination of GFAP and TTF-1 in the immunohistochemical panel can be useful in differential diagnosis. Mainstay of treatment is complete surgical excision, with adjuvant radiotherapy becoming increasingly important.

Cholesterol is a foundational molecule of biology. There is a long-standing interest in understanding how cholesterol metabolism is intertwined with cancer biology. In this review, we focus on the known connections between lung cancer and molecules mediating cholesterol efflux. A major take-home lesson is that the roles of many cholesterol efflux factors remain underexplored. It is our hope that this article would motivate others to investigate how cholesterol efflux factors contribute to lung cancer biology.

Background Thyroid Transcription Factor-1 (TTF-1) expression in lung adenocarcinoma (LUAD) has been studied for its prognostic value in early-stage and metastatic disease. Its role in brain metastasis remains unexplored. This study investigates the predictive value and association of TTF-1 status with clinicopathological variables in patients with synchronous LUAD brain metastases. Material and methods In this bicentric retrospective study, 245 patients with newly diagnosed, treatment-naïve brain metastasis undergoing resection were included. Patient data were retrieved from electronic records. Outcomes included overall and progression-free survival. Statistical analysis included Kaplan–Meier estimates and Cox proportional hazards regression. Results Mean Ki67 index in TTF-1 negative patients was 43% [95% CI 38–48%] compared to 32% [95% CI 29–35%] in TTF-1 positive (TTF-1 +) patients (p < 0.001). Tumor volume was significantly larger in TTF-1 negative (TTF-1-) patients (mean volume 24 mL [95% CI 18–31 mL]) vs. 15 mL [95% CI 12–17 mL] in TTF-1 + patients (padjust = 0.003). Perifocal edema was smaller in TTF-1- patients (mean volume: 58 mL [95% CI 45–70 mL]) vs. 84 mL [95% CI 73–94 mL] in TTF-1 + patients (padjust = 0.077). Tumor and edema volume did not correlate. TTF-1- patients showed worse overall, intracranial, and extracranial progression-free survival. In a multivariable Cox model, positive TTF-1 status was independently associated with improved outcomes. Negative TTF-1 status was associated with increased hazard for intracranial disease progression compared to extracranial progression. Conclusion In synchronous LUAD brain metastases, TTF-1 negativity reflects an aggressive phenotype with larger proliferation capacity and tumor volume. Future research should explore the underlying cellular and molecular alterations of this phenotype.