Tohru Tanizawa

Distinction of pulmonary large cell neuroendocrine carcinoma from small cell lung carcinoma: a morphological, immunohistochemical, and molecular analysis.

The distinction between pulmonary large cell neuroendocrine carcinoma and small cell carcinoma is difficult in some cases. Some propose that these carcinomas should be classified as one high-grade neuroendocrine carcinoma. We examined biological features of small cell carcinoma (n=23), large cell neuroendocrine carcinoma (n=17), and classic large cell carcinoma (n=12). The average ratio of nuclear diameter of the tumor cells to that of lymphocytes for small cell carcinoma was smaller than that for large cell neuroendocrine carcinoma (P<0.0001). The frequencies of the expressions of CD56, mASH1, TTF-1, and p16 were higher and that of NeuroD was lower in small cell carcinoma than in large cell neuroendocrine carcinoma. The frequency of loss of heterozygosity at 3p was higher in high-grade neuroendocrine carcinomas than in classic large cell carcinoma (P=0.0002). Allelic losses at D5S422 (5q33) were more frequent in small cell carcinoma than in large cell neuroendocrine carcinoma (P=0.0091). Mean fractional regional loss indices of the tumors were 0.38, 0.65, and 0.72 for patients with classic large cell carcinoma, large cell neuroendocrine carcinoma, and small cell carcinoma, respectively (P=0.0003). Five-year overall survivals of patients with classic large cell carcinoma, large cell neuroendocrine carcinoma and small cell carcinoma in stage I were 67, 73, 60%, respectively. Patients with NeuroD expression had better survivals, and those with p63 expression had poorer survivals in large cell neuroendocrine carcinoma. Patients with TTF-1 expression had poorer survivals in small cell carcinoma. Our data suggest that large cell neuroendocrine carcinoma and small cell carcinoma are different morphologically, phenotypically, and genetically, although there are some overlapping features. Although further studies are needed to analyze the biological behavior of high-grade neuroendocrine carcinomas including sensitivity to chemotherapy, the pathological distinction of large cell neuroendocrine carcinoma from small cell carcinoma may be necessary to treat the patients with neuroendocrine tumors.

Expression of an activated mammalian target of rapamycin (mTOR) in gastroenteropancreatic neuroendocrine tumors

AimsGastroenteropancreatic neuroendocrine tumors are rare, and the current WHO classification divides this tumor entity into well-differentiated (neuro)endocrine tumors, well-differentiated (neuro)endocrine carcinomas, and poorly differentiated (neuro)endocrine carcinomas. Poorly differentiated (neuro)endocrine carcinoma is extremely aggressive, and no appropriate therapeutic approach has been established. The mammalian target of rapamycin (mTOR), an important regulator of cell proliferation and protein translation, is activated in various malignancies. Recent phase II trial has revealed the efficacy of mTOR inhibitor (RAD001; everolimus) against low-to-intermediate grade neuroendocrine tumors. However, the beneficial role of mTOR inhibitor against poorly neuroendocrine carcinoma remains uncertain. The purpose of the present study was to determine the activation of mTOR in gastropancreatic neuroendocrine tumors, especially in poorly differentiated neuroendocrine carcinomas.MethodsExpression of p-mTOR(Ser2448) was assessed by immunohistochemistry in 20 gastropancreatic neuroendocrine tumors (seven well-differentiated neuroendocrine tumors, four well-differentiated neuroendocrine carcinomas, and nine poorly differentiated neuroendocrine carcinomas). Double immunohistochemistry was performed with p-Akt for patients with high p-mTOR expression.ResultsExpression of mTOR was seen in 9 (45%) of 20 gastroenteropancreatic neuroendocrine tumors. High expression of p-mTOR was seen in 6 (67%) of 9 poorly differentiated neuroendocrine carcinomas which was higher than the expression rate of well-differentiated neuroendocrine tumors and carcinomas, 3 (27%) of 11. All large cell neuroendocrine carcinomas showed high p-mTOR expression. Some tumor cells showed positive staining for p-mTOR co-expressed p-Akt.ConclusionsHigh expression rate of p-mTOR in poorly differentiated neuroendocrine carcinomas (large-cell type) may suggest the potential role of mTOR inhibitors as effective therapeutic agents for this highly malignant disease.

Rapid detection of metastasis of gastric cancer using reverse transcription loop-mediated isothermal amplification.

Tailor‐made surgeries for patients with solid malignancies have been under consideration on the basis of the development of new approaches for minor metastatic foci of malignant tumors. Accurate and reliable methods to detect metastases in biopsy specimens with certain rapidity are essential for the performance of these surgeries. The aim of this study was to develop a rapid and practical method to detect metastasis in specimens from patients with gastric carcinoma with the use of reverse transcription loop‐mediated isothermal amplification (RT‐LAMP) reaction, a novel technique for detecting mRNA expressions of targeted sequences with high sensitivity, specificity and rapidity under isothermal conditions. RT‐LAMP primers to detect cytokeratin19 (CK19) mRNA were generated and 92 lymph nodes (LNs) obtained from 9 patients with gastric cancer were tested for tumor metastases with this technique. Among 92 LNs, 15 were metastasis‐positive by routine histopathological examination. RT‐LAMP reaction detected CK19 expression in all of the pathologically positive LNs and in 16 of 77 negative LNs. Nested RT‐PCR assay for CK19 expression was also performed on 2 of the 9 cases including 32 LNs. The agreement rate of CK19 expression detection by RT‐LAMP and RT‐PCR analysis was 31/32 (97%). The RT‐LAMP technique showed similar sensitivity to detect metastases as nested RT‐PCR assay, with a rapidity comparable to that of intraoperative histopathological examination with frozen sectioning and hematoxylin and eosin staining. This method is expected to play an essential role in the performance of tailor‐made surgeries in the near future.

Molecular analysis of multifocal prostate cancer by comparative genomic hybridization.

Prostate cancer is often multifocal and shows histological heterogeneity among different tumor foci within the same prostate. We analyzed the origin and molecular basis of multifocal prostate cancer and genomic alterations associated with tumor progression.

The expression of NeuroD and mASH1 in the gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors are uncommon and their tumor biology has not been well elucidated to date. Currently the WHO classification is widely used for the diagnosis and distinction of this tumor entity, which is sometimes cumbersome. Although neuroendocrine tumor markers do exist (ie chromograninA, synaptopyhsin, etc), sensitive and specific markers that accurately predict tumor growth and tumor behavior are still absent. In the present study, we assessed the expression of transcription factors (NeuroD and mASH1) essential for the normal fetal neuronal development in 33 gastroenteropancreatic neuroendocrine tumor patients (12 well-differentiated neuroendocrine tumors, 7 well-differentiated neuroendocrine carcinomas, and 14 poorly differentiated neuroendocrine carcinomas). NeuroD was less expressed in poorly differentiated neuroendocrine carcinoma (small-cell type) compared to well-differentiated neuroendocrine tumor (carcinoid) by reverse transcription–polymerase chain reaction. Immunohistochemical staining revealed that mASH1 was highly (sensitivity of 71%) and specifically (specificity of 95%) expressed in poorly differentiated neuroendocrine carcinoma. High NeuroD expression was seen in all well-differentiated neuroendocrine carcinoma and tumor (carcinoid) patients. Low NeuroD expression was seen in 36% (5 of 14) of poorly differentiated neuroendocrine carcinoma patients, which was associated with significant shorter overall survival. The expression pattern of these transcription factors may represent the biological and pathophysiological difference of gastroenteropancreatic neuroendocrine tumors and may become a new marker for the distinction of gastroenteropancreatic neuroendocrine tumors.

The expression of hepatocyte nuclear factor-4α, a developmental regulator of visceral endoderm, correlates with the intestinal phenotype of gastric adenocarcinomas

Aims: Hepatocyte nuclear factor (HNF)‐4&agr; is a developmental regulator of the visceral endoderm, which is expressed in the embryonic gut and later in the adult intestine and colon. However, adult gastric mucosa does not express HNF‐4&agr;. We investigated the possible involvement of HNF‐4&agr; in intestinal metaplasia and the intestinalisation of gastric adenocarcinomas. Methods: Thirty‐five cases of adenocarcinomas and 46 cases of adjacent non‐neoplastic mucosa with (22 lesions) or without (24 lesions) intestinal metaplasia were immunostained for HNF‐4&agr;. The gastric or the intestinal phenotype was also examined using immunohistochemistry for MUC5AC, MUC2, CD10, and gastric‐type mucin (GTM). Adenocarcinomas were classified into the gastric type (G‐type, 42.9%), the mixed gastric and intestinal type (GI‐type, 31.4%), and the intestinal type (I‐type, 25.7%). Results: The HNF‐4&agr; expression was exclusively seen in glandular cells with intestinal metaplasia, which was correlated with MUC2 expression (p<0.05) and inversely correlated with MUC5AC expression (p<0.05). All adenocarcinomas more or less expressed HNF‐4&agr;, with an intense expression being seen in the I‐type (p<0.01) and in well‐differentiated adenocarcinomas (p<0.03). Conclusions: HNF‐4&agr; expression is associated with the intestinal phenotype of non‐neoplastic and neoplastic gastric glandular cells, suggesting a possible involvement in the establishment and/or maintenance of the intestinal phenotype of the gastric mucosa and adenocarcinomas.

Rapid diagnosis of micrometastasis of gastric cancer using reverse transcription loop-mediated isothermal amplification

Methods to detect metastases in biopsy specimens with certain rapidity and accuracy are essential to performing tailor-made surgeries for solid malignancies. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) reaction is a novel technique for detecting mRNA expression of target sequences with high sensitivity and rapidity, even from crude samples without RNA purification. Applicability to detect lymph node (LN) micrometastasis of gastric cancer was tested. Total of 26 LNs were retrieved from 10 patients with primary gastric cancer. Each LN was serially sectioned, and every set of three serial sections were tested for routine histopathological (H&E) and immunohistochemical examination with anti-cytokeratin antibodies (IHC), and RT-LAMP analysis targeted cytokeratin 19 mRNA. Results from H&E/IHC and RT-LAMP analysis were compared in each set of sections. All the sections of those containing metastatic lesions equivalent to a volume of overt metastasis (maximum diameter>2 mm), 90% of those containing micrometastasis (between 2 and 0.2 mm) and 83% of those containing isolated tumor cells (<0.2 mm) were detectable using this procedure. Total analysis from lysates of clinical specimens required<75 min. This new technique is suggested to be an alternative to rapid diagnosis of micrometastasis based on conventional histopathological analysis.

Postoperative recurrence of an IPMN of the pancreas with a fistula to the stomach

We report on a case of a 74 year old man who was diagnosed with a recurrence of non-invasive carcinoma of intraductal papillary mucinous neoplasm (non-invasive IPMN) by postoperative gastroscopy (GS). A pylorus preserving pancreatico duodenectomy for IPMN in the pancreatic head was performed. A histopathological study revealed non-invasive adenocarcinoma. At first, the local recurrence of the tumor around the superior mesenteric artery circumference was diagnosed and disappeared with gemcitabine. Later, the GS showed the elevated lesion with mucin hypersecretion in the remnant stomach. The lesion had a central dip and a fistula common to the pancreas was confirmed on fisterography. We diagnosed a recurrence of IPMN and administered chemotherapy again. However, he died of his original illness. There are no reports of postoperative recurrence of IPMN checked by GS. It should be remembered that the elevated lesion of the remnant stomach is considered as one of the recurrent patterns of IPMN.

Metastatic germ cell tumor of the lung masquerading as primary rhabdomyosarcoma

Two years after testicular resection was carried out in a 40‐year‐old man that revealed mixed germ cell tumor of more than one histological type (seminoma, embryonal cell carcinoma, and yolk sac tumor), he presented with an asymptomatic pulmonary nodule in his left lower lobe. Video‐assisted thoracoscopic partial resection of the tumor revealed a 24 × 20 mm teratoma with somatic‐type malignancy in which pleomorphic rhabdomyosarcoma was a major element. One year later, asymptomatic tumor recurrence occurred at both edges of the stapler line as 22 × 20 mm and 10 × 5 mm nodules composed only of pleomorphic rhabdomyosarcoma. Throughout the course there was no abdominal lymph node swelling detected by computed tomography (CT) and tumor markers were normal. Adjuvant chemotherapy was started after the tumor recurrence. Currently, the patient is still undergoing chemotherapy 5 months after the tumor recurrence. In conclusion, despite the fact that primary pulmonary rhabdromyosarcoma is a rare neoplasm, metastatic pulmonary germ cell tumor with somatic‐type malignancy showing predominantly rhabdomyosarcomatous differentiation should be considered in the differential diagnosis of such lesions of the lung.