Visualization of microvessels by angiography using inverse-Compton scattering X-rays in animal models.

The fundamental performance of microangiography has been evaluated using the S-band linac-based inverse-Compton scattering X-ray (iCSX) method to determine how many photons would be required to apply iCSX to human microangiography. ICSX is characterized by its quasi-monochromatic nature and small focus size which are fundamental requirements for microangiography. However, the current iCSX source does not have sufficient flux for microangiography in clinical settings. It was determined whether S-band compact linac-based iCSX can visualize small vessels of excised animal organs, and the amount of X-ray photons required for real time microangiography in clinical settings was estimated. The iCSX coupled with a high-gain avalanche rushing amorphous photoconductor camera could visualize a resolution chart with only a single iCSX pulse of ∼3 ps duration; the resolution was estimated to be ∼500 µm. The iCSX coupled with an X-ray cooled charge-coupled device image sensor camera visualized seventh-order vascular branches (80 µm in diameter) of a rabbit ear by accumulating the images for 5 and 30 min, corresponding to irradiation of 3000 and 18000 iCSX pulses, respectively. The S-band linac-based iCSX visualized microvessels by accumulating the images. An iCSX source with a photon number of 3.6 × 10(3)-5.4 × 10(4) times greater than that used in this study may enable visualizing microvessels of human fingertips even in clinical settings.

Electrorheological effect and electro-optical properties of side-on liquid crystalline polysiloxane in a nematic solvent.

The electrorheological (ER) effect and the electro-optical properties of a ''side-on'' liquid crystalline polysiloxane (PS) are investigated. A large ER effect is observed and the response to the shear stress of neat PS in the nematic phase is shown to be affected by the shear rate. PS is also mixed with a low-molar nematic liquid crystal (5CB) in order to improve the response behavior to the applied electric field. The rheological properties of such mixtures are highly dependent on the concentration of 5CB. The composites respond faster to the applied electric field and have improved electro-optical properties. This study offers a new perspective on the development of liquid crystal materials for the ER effect.

Liposarcoma of the pleural cavity.

Liposarcoma rarely occurs in the pleura or thoracic cavity, and few reports appear in the literature. We hypothesized that combining clinicopathologic, immunohistochemical, and fluorescence in situ hybridization methods would allow definite diagnoses. Using formalin-fixed, paraffin-embedded blocks, we examined 6 atypical lipomatous tumor/well-differentiated liposarcomas (ALT/WDLPS), 5 dedifferentiated liposarcomas (DDLPSs), 2 pleomorphic liposarcomas, and 1 myxoid liposarcoma (MLPS). We used the Kaplan-Meier method and the Wilcoxon test for survival analysis for prognostic factor evaluation. Histologically, ALT/WDLPS was composed of a relatively mature adipocytic proliferation, accompanied by some lipoblasts. DDLPS exhibited round-to-oval tumor cells with a high nucleus-to-cytoplasm ratio that had proliferated in nests, accompanied in case 10 by some giant cells but no fatty cells. The pleomorphic type contained a varying proportion of pleomorphic lipoblasts. MLPS displayed uniform round- to oval-shaped cells and small signet-ring lipoblasts in a myxoid stroma. Immunohistochemically, 11 (79%), 11 (79%), and 10 (71%) of 14 cases were positive for S-100, p16, and CDK4, respectively. Six of the 14 cases (43%) were positive for MDM2 and adipophilin. One case of ALT/WDLPS and 3 cases of DDLPS exhibited MDM2 amplification by fluorescence in situ hybridization (Vysis LSI MDM2 SpectrumGreen Probe plus Vysis CEP 12 SpectrumOrange probe). ALT/WDLPS was the most favorable type for survival, while adipophilin tended to be a negative prognostic factor for pleural liposarcoma. For a firm diagnosis of liposarcoma in the pleura, immunohistochemistry for CDK4, MDM2, and adipophilin together with MDM2 gene amplification by fluorescence in situ hybridization may be an important diagnostic tool.

Expression of P2X4R mRNA and protein in rats with hypobaric hypoxia-induced pulmonary hypertension.

BACKGROUND: The experimental pulmonary hypertension that develops in hypobaric hypoxia is characterized by structural remodeling of the heart. The P2X4 receptor (P2X4R) controls vascular tone and vessel remodeling in several blood vessels, and it has emerged as a key factor in the enhancement of cardiovascular performance. METHODS AND RESULTS: To study the possible effects of hypobaric hypoxia on the P2X4R-synthesis system, 150 male Wistar rats were housed in a chamber at the equivalent of the 5,500 m altitude level for 21 days. After 14 days' exposure to hypobaric hypoxia, pulmonary arterial pressure (PAP) was significantly increased. In the right ventricle (RV) of the heart, P2X4R expression was significantly increased on days 1 and 14 (mRNA) and on days 7 and 21 (protein) of hypobaric hypoxic exposure. Immunohistochemical staining for P2X4R protein became more intense in RV in the late phase of exposure. These changes in P2X4R synthesis in RV occurred alongside the increase in PAP. In addition, P2X1R and P2Y2R mRNA levels in the RV were significantly increased on days 1, 14, and 21, and day 5, respectively, of exposure. The level of P2X1R protein in the RV was significantly increased on day 21 of exposure. CONCLUSIONS: Conceivably, P2 receptors, including P2X4R and P2X1R, might play roles in modulating the RV hypertrophy that occurs due to pulmonary hypertension in hypobaric hypoxia.

Malignant pleural mesothelioma with heterologous elements.

AIMS: Malignant pleural mesothelioma with heterologous elements (such as osseous, cartilaginous or rhabdomyoblastic differentiation) is very rare. We tried to differentiate such mesothelioma cases from extraskeletal pleural osteosarcoma, which is very challenging. METHODS: We compared 10 malignant pleural mesotheliomas (three biphasic and seven sarcomatoid types) with two pleural osteosarcomas using clinicopathological and immunohistochemical methods, and also fluorescence in situ hybridisation (FISH) to examine for homozygous deletion of p16. RESULTS: The median age was 72 years for mesotheliomas, and 69 years for osteosarcoma. For mesothelioma, eight cases were male and two were female. Growth was diffuse in all mesothelioma cases except case 10, where it was localised, as it was for the two osteosarcomas. Among mesothelioma cases, 80% displayed osteosarcomatous and 60% chondromatous elements, while 10% exhibited rhabdomyoblastic ones. Immunohistochemical labelling for calretinin and AE1/AE3 was present in 8/10 and 7/10 mesotheliomas, respectively, but in only one osteosarcoma. Loss of methylthioadenosine phosphorylase was seen in 5/7 mesotheliomas. FISH analysis revealed homozygous deletion of p16 in 5/8 mesothelioma and 2/2 osteosarcoma. Median survival was 6.5 months after biopsy or surgical operation in mesothelioma, and 12 months after operation in osteosarcoma. CONCLUSIONS: Although median survival was longer for osteosarcoma than for malignant mesothelioma, we could not differentiate mesothelioma from pleural osteosarcoma on the combined basis of clinicopathological and immunohistochemical data, and FISH analysis. However, diffuse growth was more frequent in mesothelioma than in osteosarcoma.

Glucose-regulated protein 78 expression in urothelial carcinoma of the upper urinary tract.

OBJECTIVE: To examine glucose-regulated protein 78 (GRP78; a major molecular chaperone at the endoplasmic reticulum, strongly expressed in several tumours) expression in urothelial carcinoma (UC) of the upper urinary tract (UUT) and to evaluate the diagnostic and progressive importance of GRP78 expression in UC-UUT. PATIENTS AND METHODS: We investigated GRP78 expression (using immunohistochemistry) in 126 UC-UUTs to assess its relevance to progression. GRP78 overexpression was recognised in 23 (18.3%) of tumour samples. RESULTS: There was no association between GRP78 overexpression and clinicopathological findings, except for an association with low grade in invasive tumours. GRP78 overexpression significantly improved the disease-free survival rate in all patients (according to univariate and multivariate analyses), but did not alter the overall survival rate. CONCLUSION: The detection of GRP78 overexpression would appear to provide valuable information for the prognosis of UC-UUT.

Nonviral retrograde gene transfer of human hepatocyte growth factor improves neuropathic pain-related phenomena in rats.

Peripheral nerve injury occasionally causes chronic neuropathic pain with hyperalgesia and allodynia. However, its treatment is difficult. Here, we used a chronic constriction injury (CCI) model in rats to investigate the effects on experimental neuropathic pain of the human hepatocyte growth factor (HGF) gene delivered into the nervous system by retrograde axonal transport following its repeated intramuscular transfer, using liposomes containing the hemagglutinating virus of Japan (HVJ). CCI (control) rats exhibited marked mechanical allodynia and thermal hyperalgesia, and decreased blood flow in sciatic nerve and hind paw. All these changes were significantly reversed by HGF gene transfer. In the sciatic nerve in HGF-treated rats, the size-frequency distributions for myelinated and unmyelinated axons each showed a rightward shift, the number of myelinated axons >5 microm in diameter was significantly increased, and the mean diameter of unmyelinated axons was significantly increased (versus CCI rats). Levels of P2X3, P2X4, and P2Y1 receptor mRNAs, and of interleukin-6 (IL-6) and activating transcription factor 3 (ATF3) mRNAs, were elevated in the ipsilateral dorsal root ganglia and/or sciatic nerve by CCI, and these levels were decreased by HGF gene transfer. These results may point toward a potential new treatment strategy for chronic neuropathic pain in this model.

Lymphohistiocytoid mesothelioma of the pleura.

Lymphohistiocytoid mesothelioma (LHM), reported to be a rare variant of sarcomatoid mesothelioma, is challenging to differentiate from non-Hodgkin's lymphoma due to marked lymphocytic infiltration. To aid accurate recognition of LHM, we examined immunohistochemical, in situ hybridization (ISH) of Epstein-Barr virus RNA (EBER-1) mRNA, fluorescence ISH (FISH) for homozygous deletion of 9p21, and asbestos analysis in four cases (three men and 1 woman). Three patients died, while Case 4 was still alive 19 months after extrapleural pneumonectomy. Histologically, these cases were characterized by heavy lymphocytic infiltration. All neoplastic cells were positive for calretinin, AE1/AE3, and epithelial membrane antigen, but negative for CEA. EBER1 factor was negative. FISH analysis demonstrated homozygous deletion of the 9p21 locus in three of the four cases. In Case 1: (i) autopsy findings showed mesothelioma primarily located in the right parietal pleura, but metastasized into the left lung and abdominal organs; (ii) the histological findings at autopsy indicated sarcomatoid mesothelioma; and (iii) we found asbestos bodies and fibers in extracts from lung tissue (Cases 1 & 4) using digestion with bleaching fluid. LHM, an infrequent variant of sarcomatoid mesothelioma, displayed homozygous deletion of the 9p21 locus (three of four cases), and has a relatively favorable prognosis for the sarcomatoid type.

Poorly differentiated adenocarcinoma with signet-ring cell carcinoma of the extrahepatic bile duct in a 42-year-old Japanese female: a case report.

Poorly differentiated adenocarcinoma without papilla or tubule formation of the extrahepatic bile duct is rare. Here we present a case (a 42-year-old Japanese woman) without either pancreatobiliary maljunction or liver disease. The patient had obstructive jaundice. Imaging studies revealed a bile duct tumor obstructing the common bile duct and invading the surrounding tissues. Pathologic examination revealed a dense periductal growth of poorly differentiated adenocarcinoma containing signet-ring cells, but without papilla or tubule formation in the extrahepatic bile duct. The tumor cells directly invaded the pancreatic parenchyma and the portal vein. In the extrahepatic bile duct, poorly differentiated adenocarcinoma may be established as a distinct clinicopathologic entity if the tumors are characterized by: 1) the absence of papilla or tubule formation, 2) Asian preponderance, 3) occurrence at a younger age than is usual for patients with biliary cancers, and 4) an aggressive mural invasiveness.

Sarcoidosis-associated hepatocellular carcinoma.

Sarcoidosis is a systemic granulomatous inflammation of unknown etiology, and seems to involve the liver parenchyma in most cases. However, sarcoidosis-associated hepatocellular carcinoma is rare. We report here a case in which a hepatocellular carcinoma occurred within the liver, which was probably involved as a result of systemic sarcoidosis. A 57-year-old Japanese man had been followed up for 2 years because of diabetic nephropathy and sarcoidosis. On admission for pneumonia, imaging studies revealed an unexpected hepatic tumor. Histology revealed a hepatocellular carcinoma accompanied by T-lymphocytic infiltration and marked granulomatous inflammation, which was surrounding some tumor nodules. The background liver parenchyma exhibited a moderate degree of fibrosis with granulomatous inflammation. The patient had no other apparent liver disease such as viral hepatitis, steatohepatitis, or primary biliary cirrhosis. Therefore, in the present case, sarcoidosis may be considered the probable background etiology for hepatocarcinogenesis.

Soluble elastin decreases in the progress of atheroma formation in human aorta.

BACKGROUND: The serum levels of soluble elastin increase in patients with aortic dissection, but its distribution and characteristics are unclear. METHODS AND RESULTS: The 173 aortic specimens were categorized into 4 groups under microscopy (non-atherosclerotic aorta, n=13; fiber-rich plaque, n=77; lipid-rich plaque, n=66; ruptured plaque, n=17). Soluble elastin was abundant within the intima of both the non-atherosclerotic aorta and fiber-rich plaque, rather than in the media, and was decreased within the intima of lipid-rich and ruptured plaques. Soluble elastin levels decreased with progress of atherosclerosis (6.0 +/-0.3 microg/mg protein in non-atherosclerotic aorta; 5.8 +/-0.2 microg/mg protein in fiber-rich plaque; 4.9 +/-0.2 microg/mg protein in lipid-rich plaque; 2.8 +/-0.4 microg/mg protein in ruptured plaque, P<0.05). As well, both matrix metalloprotease-9 activity and elastin mRNA expression showed inverse distribution against soluble elastin (r=0.437, P<0.0001; r=0.186, P<0.05, respectively). Multivariable analysis revealed a decrease in the level of soluble elastin in ruptured plaque (2.8 +/-0.4 microg/mg protein in ruptured plaque, n=18; 5.5 +/-0.2 microg/mg protein in non-ruptured plaque, n=155, P<0.01). Furthermore, western blot showed soluble elastin consists of heterogeneous molecular pattern proteins. CONCLUSIONS: Both the synthesis and degradation of elastin may be enhanced in active atherosclerotic lesions.

Malignant pleural mesothelioma initially diagnosed on cervical lymph node biopsy.

Reported herein is a case of malignant pleural mesothelioma, initially diagnosed on cervical lymph node biopsy. A 58-year-old man, without obvious evidence of asbestos exposure, exhibited repeated pleural effusion (cause unclear), which was resolved by diuretics. A neck mass was apparent and was identified pathologically as a lymph node metastasis of malignant mesothelioma. F-18 fluorodeoxyglucose positron emission tomography/CT established the diagnosis of malignant pleural mesothelioma. Two conclusions emerge from this report: (i) cervical lymph node metastasis of pleural mesothelioma, although rare, should be included in differential diagnosis; and (ii) positron emission tomography/CT is useful for establishing a diagnosis of mesothelioma.

Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features.

The earliest pathological events in the development of malignant pleural mesothelioma (MPM) are not understood. The aim of the present study was to elucidate the early histopathological features of MPM. A total of 16 extrapleural MPM pneumonectomy patients were investigated. Early stage mesothelioma was arbitrarily defined as a tumor < or =5 mm in thickness regardless of the nodal status or other organ involvement. Eight of these patients (six with epithelioid, two with biphasic) had early stage mesothelioma by this definition. Macroscopically there was no visible tumor, but the parietal and visceral pleura were thickened and there was focal adhesion between them. Microscopically, the mesothelioma lesions were multifocal and discontinuous on the pleura. In extremely early cases of epithelioid mesothelioma, tumor cells were generally arrayed in a single layer, but papillary proliferation was observed elsewhere. In sarcomatoid mesothelioma, mesothelioma cells proliferated, forming multiple small polypoid nodules on the pleura. Epithelial membrane antigen was helpful to distinguish reactive from neoplastic mesothelium, but glucose transporter-1 was not. Mesothelioma cells disseminate diffusely throughout the parietal and visceral pleura and mediastinal fat tissue before becoming visible. Stage Ia mesothelioma (neoplasm limited to the parietal pleura) would not be observed in daily practice.

Malignant amelanotic melanoma of the pleura without primary skin lesion:an autopsy case report.

Melanoma metastasizing to the lungs is common, but primary pulmonary or pleural melanoma is extremely rare. We present an autopsy case of malignant melanoma of the pleura without primary skin lesion in a 49-year-old man. A mass found in the right chest was diagnosed as spindle cell sarcoma by antemortem fine-needle aspiration cytology. At autopsy, a yellow-white tumor located primarily in the right visceral pleura (diagnosed as an amelanotic melanoma) was found to have invaded into the right lung, right parietal pleura, and right diaphragm, and to have metastasized into the left lung and visceral pleura, thyroid, and left adrenal gland. No primary site was found. The tumor cells were positive for S100 and focally positive for HMB-45, but negative for other markers. Immuno-histochemical examination for S100 and HMB-45 would thus appear to be useful for the diagnosis of an amelanotic melanoma.

Clinicopathologic study of deciduoid mesothelioma using SMARCB1/INI1 immunohistochemistry and fluorescence in situ hybridization.

Deciduoid mesothelioma is a rare variant of epithelioid mesothelioma. Malignant rhabdoid tumors, renal medullary carcinoma, and some synovial sarcomas show a loss of SMARCB1/INI1 protein, a member of the SWI/SNF chromatin-remodeling complex. All of those tumors are known to have rhabdoid cells. Some mesothelioma cases, such as those of the deciduoid type, have also been reported to possess such rhabdoid features. Since this topic has not been studied in malignant mesothelioma, we analyzed the immunohistochemical expression of SMARCB1/INI1 in malignant mesotheliomas [45 epithelioid type (including 9 deciduoid type), 12 biphasic type, and 17 sarcomatoid type]. We employed (a) SMARCB1/INI1 immunohistochemistry, using an antibody to the INI1 gene product and (b) Fisher exact test, logistic regression analysis, the Kaplan-Meier method, and the Wilcoxon test for survival analysis for prognostic factor evaluation (SAS 9.4; SAS Institute, Cary, NC). The results showed that 17 of 74 (23%) malignant mesothelioma cases (epithelioid: 24%; biphasic; 8%; sarcomatoid; 29%) had reduced SMARCB1/INI1 expression. Reduced SMARCB1/INI1 expression appeared to be more frequent in the deciduoid type (67%), of which there were admittedly only a few cases, than in either the epithelioid type (14%) or biphasic type (8%), whether or not rhabdoid cells were present, but not different between the deciduoid and sarcomatoid types. However, there was no statistically significant difference in prognosis between malignant mesotheliomas with reduced versus preserved SMARCB1/INI1 protein expression. The results suggest that in differential diagnosis, cases with reduced SMARCB1/INI1 protein expression should not be excluded from a diagnosis of malignant mesothelioma.

How can we strengthen pathology services in Cambodia?

Rapid economic growth and a changing disease burden have increased the demand for pathology services in Cambodia. This paper describes the status of pathological services and international support for pathology professionals in Cambodia, and discusses future needs for strengthening pathology services. In 2016, there were only four pathologists and 18 pathology technologists in Cambodia. A postgraduate course in pathology was created in 2015, and five residents became certified in 2018. Besides multinational support with lectures and practice for pathologists, the Japanese team provides on-the-job training for pathology technologists to improve slide preparation for diagnosis. A clinicopathological conference was introduced to strengthen the communication among pathologists, pathology technologists, and gynecologists. Although there is a long way to go to reach high quality pathological services, coordination among international partners needs to continue, as does the balance between human resource development for pathology professionals, to provide a higher level of care to local citizens.

Expression of occludin and claudins 1, 3, 4, and 7 in urothelial carcinoma of the upper urinary tract.

The contacts between epithelial cells are maintained mainly by adherens junctions and tight junctions (TJs). However, the role of TJ proteins in cancer is not well understood. We studied the expression of occludin and 4 claudins to assess their importance in the progression of urothelial carcinoma of the upper urinary tract (UC-UUT). In 129 cases, we examined their expression using immunohistochemical analysis and also their relationships to clinicopathologic parameters and clinical outcome. Positive expression of occludin and claudins 1, 3, 4, and 7 were recognized in 117 (90.7%), 113 (87.6%), 95 (73.6%), 127 (98.4%), and 123 (95.3%) of tumor samples, respectively. Claudin-3 expression was significantly associated with stage, grade, and pattern of growth. Claudins 1 and 4 expression was significantly associated with stage. However, neither occludin nor claudin-7 expression was associated with clinicopathologic findings. When tumors with scores below the median for a given protein were classified as the "low expression group," univariate analysis of overall survival revealed that claudins 1 and 3 had a significant effect on overall survival. Detection of claudins 1, 3, and 4 would seem to provide valuable information about the progression of UC-UUT.

Telomere length and telomerase expression in atypical adenomatous hyperplasia and small bronchioloalveolar carcinoma of the lung.

Telomeres are located at the ends of every human chromosome and are subject to shortening at each cycle of cell division in cell senescence and early carcinogenesis. We examined the expression of telomeric DNA in 21 atypical adenomatous hyperplasias (AAHs) and 40 bronchioloalveolar carcinomas (BACs) measuring 2 cm or less in greatest diameter using fluorescent in situ hybridization and the expression of human telomerase reverse transcriptase (hTERT) messenger RNA (mRNA) in 35 AAHs and 37 BACs. The mean numbers of telomeric signals per nucleus were 5.0 in AAH and 7.4 in BAC, each significantly less than for normal cells (14.7; P < .0001), but the mean number of telomeric signals for AAH and BAC was not statistically different (P = .22). In "benign" lung samples, the pattern of expression of hTERT mRNA was barely detected in the nonciliated cells of the bronchioles and alveolar type II cells. Positive expression of hTERT mRNA was recognized in 66% of AAHs and 97% of BACs. Our results demonstrate telomere shortening, indicating its presence in the earliest phase of pulmonary carcinogenesis. Telomere length and telomerase may be involved in carcinogenesis in the lung.

Expression of LAT1 predicts risk of progression of transitional cell carcinoma of the upper urinary tract.

L-type amino acid transporter 1 (LAT1), a neutral amino acid transporter, requires covalent association with the heavy chain of 4F2 cell surface antigen (4F2hc) for its functional form. We investigated the importance of LAT1 and 4F2hc expressions to progression in upper urinary tract cancer. We examined their expressions and their relationships to clinicopathologic parameters and clinical outcome in 124 cases. Positive expressions of LAT1 (protein and messenger ribonucleic acid) and 4F2hc (protein) were recognized in 79.8, 89.5, and 87.9% of tumor samples, respectively. In tumor cells, LAT1 protein was detected either as nodular granules within the cytoplasm or diffusely within the cytoplasm and/or on plasma membrane. In the normal urothelium, its expression was detected as nodular granules within the cytoplasm. A correlation with stage was shown for LAT1 protein expression and for a cooperative expression of LAT1 protein with 4F2hc protein (active form of LAT1 protein). Further, in all tumors, a cooperative expression of LAT1 protein and 4F2hc protein was significantly correlated with both overall and disease-free survival rates in the univariate analysis but not in the multivariate analysis. In conclusion, the detection of the active form of LAT1 protein would appear to be of value in informing the risk of progression in transitional cell carcinoma of the upper urinary tract.

Telomere length, telomerase activity, and expressions of human telomerase mRNA component (hTERC) and human telomerase reverse transcriptase (hTERT) mRNA in pulmonary neuroendocrine tumors.

BACKGROUND: Telomeres are important for chromosome structure and function, protecting them against degradation. However, few studies have examined telomeres in pulmonary neuroendocrine (NE) tumors. METHODS: We investigated deparaffinized sections obtained from 70 primary NE lung tumors [34 typical carcinoids (TCs), 10 atypical carcinoids (ACs), 16 large cell neuroendocrine carcinoma (LCNECs) and 10 small cell lung carcinomas (SCLCs)]. RESULTS: Positive expressions of human telomerase mRNA component (hTERC) and human telomerase reverse transcriptase (hTERT) mRNA were recognized, respectively, in 58% and 74% of TCs, and in 100% and 100% of ACs, LCNECs and SCLCs. Alteration of telomere length was greater in both LCNECs and SCLCs than in TCs. Telomerase activity was detected in LCNECs, but not in TCs. By the reverse-transcriptase polymerase chain reaction (RT-PCR), hTERC mRNA was detected in 100% of LCNECs and TCs examined, while hTERT mRNA was detected in 67% of LCNECs, but not at all in TCs. CONCLUSIONS: These results suggest that alterations in telomere length, telomerase activity, and the expression of hTERT mRNA may (i) play roles in pathogenesis in pulmonary neuroendocrine tumors, and (ii) be a useful tool for differential diagnosis between TCs and LCNECs.