[Thymic carcinoid accompanied by elevation of serum gastrin-releasing peptide precursor; report of a case].

A 74-year-old male was admitted with an abnormal mediastinal shadow. Computed tomography (CT) and magnetic resonance imaging (MRI) of the thorax showed an anterior mediastinal mass without invasion to the ascending aorta and pulmonary artery. In addition, serum gastrin-releasing peptide precursor (Pro GRP) was increased (60.6 pg/ml, normal range <46 pg/ml). Video-assisted thoracoscopic biopsy demonstrated that the mass was thymic carcinoid. Therefore, median sternotomy was performed to facilitate thymectomy, including the tumor with partial resection of the left upper lobe and pericardium. The patient received mediastinal irradiation postoperatively. The postoperative serum level of Pro GRP decreased to the normal limit 6 months later. Although a biological relationship between Pro GRP and thymic carcinoid was not proven, it might be useful marker for detecting tumor recurrence.

Close correlation between chronic sclerosing sialadenitis and immunoglobulin G4.

In four patients with chronic sclerosing sialadenitis, serum immunoglobulin G4 concentration was markedly increased and abundant infiltration of immunoglobulin G4-positive plasma cells was observed in the salivary glands. Autoimmune pancreatitis occurred in the two patients during follow up. Chronic sclerosing sialadenitis and autoimmune pancreatitis would appear to show essentially the same pathophysiological mechanism. Measurement of serum immunoglobulin G4 concentration is useful in differentiating chronic sclerosing sialadenitis from neoplasia.

A novel case with germline p53 gene mutation having concurrent multiple primary colon tumours.

During a search for causative genes in patients with concurrent multiple primary colon tumours, we found a novel case with a germline mutation of the p53 gene, from GCC (Ala) to GTC (Val) at codon 189. Of the six primary colon tumours that this patient had, one large advanced carcinoma exhibited a somatic p53 mutation and a somatic APC mutation, in addition to the germline p53 mutation. Two early carcinomas and three adenomas had somatic APC mutations but no somatic p53 mutation or loss of the p53 allele. K-ras-2 mutations were detected in an advanced carcinoma and an early carcinoma. The present results suggest that a patient with a certain type of germline p53 mutation is predisposed to concurrent multiple colon tumours. It is also suggested that in such a patient, a somatic APC mutation is involved in tumour formation and that an additional somatic p53 mutation contributes to tumour progression.

Gastrointestinal stromal tumors and KIT-positive mesenchymal cells in the omentum.

Gastrointestinal stromal tumor (GIST) is currently considered to be derived from the interstitial cells of Cajal (ICC). To test the hypothesis that omental mesenchymal tumor is also a type of GIST, we evaluated the expression of specific molecules in GIST, and c-kit gene mutation in omental mesenchymal tumors, and we identified a possible counterpart of ICC in the omentum. Immunohistochemically, all of the omental mesenchymal tumors (n = 5) were positive for both KIT and CD34, and three of the five tumors were also positive for an embryonic form of smooth-muscle myosin heavy chain (SMemb). Polymerase chain reaction-single-strand conformational polymorphism analysis (PCR-SSCP) and direct sequencing revealed mutations in c-kit gene exon 11 in all five tumors. As for the ICC counterparts in the omentum, there were some KIT-positive mesenchymal cells resembling ICC at the surface of the omentum. Double fluorescence immunostaining, using anti-KIT polyclonal antibodies and monoclonal antibodies against other molecules, demonstrated that KIT-, CD34- and SMemb-positive cells were present just beneath the mesothelial cells of the omentum. These results show that omental mesenchymal tumor corresponds to GIST of the omentum, and that KIT-positive bipolar mesenchymal cells may be a counterpart of ICC in the gastrointestinal tract. Identification of a new type of KIT-positive mesenchymal cell in the omentum may lead to the discovery of a new physiological role for this organ.

Detection of t(I 1; 18) in MALT-type lymphoma with dual-color fluorescence in situ hybridization and reverse transcriptase-polymerase chain reaction analysis.

t(11:8) is a recurrent chromosomal abnormality observed in mucosa-associated lymphoid tissue (MALT)-type lymphoma. API2 and MLT genes have been implicated. The authors devised a dual-color interphase fluorescence in situ hybridization (FISH) system to detect splitting of 11q22 and its fusion with 18q21. Subjects were 44 cases of extranodal lymphoma and cases of primary macroglobulinemia. Whenever RNA was available, reverse transcriptase-polymerase chain reaction followed by sequence analysis was performed. Positive cases by dual-color FISH analysis were restricted to MALT-type lymphoma and one case of primary macroglobulinemia. Among 24 cases of MALT-type lymphoma, 14 (58%) (4 gastric, 5 pulmonary, 3 orbital, 1 salivary, and 1 thyroid lymphomas) had splitting of the 11q22 region probes and fusion of signals suggesting the translocation of chromosome 11 and 18. Reverse transcriptase-polymerase chain reaction analysis showed the API2/MLT gene fusion in 9 of 10 cases. Sequence analyses showed three different modes of involvement of the MLT gene, whereas the breakpoint at API2 was the same. Monoclonal component of serum immunoglobulin M was observed in 3 of 14 positive cases for the translocation. Direct visualization using dual-color FISH on samples serves as a molecular tool for management of MALT-type lymphoma with API2/MLT gene fusion.

Somatic mutations of LKB1 and beta-catenin genes in gastrointestinal polyps from patients with Peutz-Jeghers syndrome.

Peutz-Jeghers syndrome (PJS) is characterized by multiple gastrointestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer, mainly in the gastrointestinal tract. We examined mutations of the LKB1, beta-catenin, APC, K-ras, and p53 genes in 27 gastrointestinal hamartomatous polyps from 10 patients in nine PJS families. Of these hamartomatous polyps, one intestinal polyp had an adenomatous lesion, and one gastric polyp contained adenomatous and carcinomatous lesions. Germ-line mutations of the LKB1 gene were detected in six PJS families. Somatic mutations of the LKB1 gene were found in 5 polyps, whereas loss of heterozygosity (LOH) at the LKB1 locus at 19p was seen in 14 other polyps. In adenomatous lesions microdissected from hamartomatous polyps, both beta-catenin mutation and 19p LOH were detected. Furthermore, a carcinomatous lesion in a gastric hamartomatous polyp was found to contain a mutation of the p53 gene and LOH at the p53 locus in addition to LOH at the LKB1 locus and a beta-catenin mutation. K-ras mutations were detected in a few polyps, whereas no APC mutation or 5q LOH was detected in hamartomatous polyps. These results suggest that gastrointestinal hamartomatous polyps in PJS patients develop through inactivation of the LKB1 gene by germ-line mutation plus somatic mutation or LOH of the unaffected LKB1 allele, and that additional mutations of the beta-catenin gene and p53 gene convert hamartomatous polyps into adenomatous and carcinomatous lesions.

Molecular evidence for multicentric development of thyroid carcinomas in patients with familial adenomatous polyposis.

Familial adenomatous polyposis is characterized by multiple colorectal adenomas and an increased incidence of colorectal carcinomas. Patients also develop various extracolonic tumors, of which, thyroid carcinoma is common in young females. The occurrence of multiple carcinomas in one thyroid is frequently observed, although some carcinomas are solitary. To clarify whether each carcinoma develops independently or metastatically spreads from the first one formed, we analyzed the adenomatous polyposis coli (APC) gene mutation in each carcinoma. We found that each carcinoma had a different somatic mutation of the APC gene. This is molecular confirmation for the multicentric development of thyroid carcinomas in familial adenomatous polyposis through biallelic inactivation of the APC gene.

Nuclear localization of immunoreactive beta-catenin is specific to familial adenomatous polyposis in papillary thyroid carcinoma.

Thyroid carcinoma is the first symptom in some patients with familial adenomatous polyposis (FAP). We evaluated the cellular localization of beta-catenin in thyroid carcinomas associated (n = 4) or not associated (n = 173) with FAP, since loss of functional protein of the adenomatous polyposis coli (APC) gene leads to nuclear accumulation of beta-catenin in adenomas and carcinomas of the FAP colon. Immunoreactive beta-catenin was demonstrated at the cell membrane of glandular cells of the non-neoplastic thyroid and non-FAP carcinomas. On the other hand, cytoplasmic and nuclear accumulation of beta-catenin is specific to FAP-associated papillary carcinomas. The abnormality in the APC / beta-catenin pathway is thus also important in FAP-associated thyroid carcinoma, and beta-catenin immunohistochemistry is a feasible screening method to identify occult FAP in young patients with thyroid tumors.

Spermatic cord metastases from gastric cancer with elevation of serum hCG-beta: a case report.

Spermatic cord metastases from gastric cancer are rare. We here document a case involving a gastric cancer that mimicked primary testicular tumor because of elevation of the serum human chorionic gonadotropin-beta (hCG-beta). The possibility of metastasis or recurrence of prior malignancies should therefore be considered when the clinical features described here are encountered, although elevation of hCG-beta is rare with tumors other than those in testis.

CD70 expression in thymic carcinoma.

CD70, a type II transmembrane glycoprotein, is a member of the tumor necrosis factor (TNF) family that mediates the interaction between B- and T-lymphocytes. CD70 has been shown to be expressed by malignant lymphoma, especially Hodgkin's disease, and by nasopharyngeal carcinoma, both of which are frequently associated with Epstein-Barr virus (EBV). In this study, we investigated the expression of CD70 in epithelial cells of various types of thymic epithelial tumors and its association with EBV. Immunohistochemical expression of CD70 was studied on frozen tissue. In a series of 27 thymic epithelial tumors, including thymic carcinomas (n = 8), atypical thymomas (n = 5), thymomas (n = 13), and thymic carcinoid (n = 1), 7 (88%) thymic carcinomas and 1 (20%) atypical thymoma showed positive immunoreactivity for CD70, whereas CD70 was not detected in other tumors. Twenty-four intrathoracic malignant epithelial tumors of nonthymic origin, including lung (n = 17), esophagus (n = 5), and mesothelium (n = 2), showed no immunoreactivity for CD70. Northern blot analysis also revealed that CD70 messenger RNA was expressed in 2 of 2 thymic carcinomas, 0 of 2 atypical thymomas. and 0 of 2 thymomas. All of the 27 thymic epithelial tumors were EBV-negative as assessed by EBV-encoded small RNA in situ hybridization. The expression of CD70 is closely related to the pathogenesis of thymic carcinoma but unrelated to EBV infection in the thymus.

MEN1 gene mutations in sporadic neuroendocrine tumors of foregut derivation.

Foregut-derived neuroendocrine (NE) tumors occur sporadically or in association with multiple endocrine neoplasia type 1 (MEN1) syndrome. Thirty-nine sporadic NE tumors of foregut derivation (six thymic, 21 bronchial, three gastric, and nine pancreatic tumors) as well as two hindgut-derived rectal carcinoids for somatic MEN1 gene mutation were analyzed by direct sequencing analysis. Five tumors showed mutations: nonsense mutations (Q393X and R98X) in thymic and pancreatic NE tumors, respectively, a 4 b.p. deletion (357del4) in a gastric NE carcinoma, and missense mutations (D172Y and S178Y) in pancreatic NE tumors. No mutation was identified in pulmonary or rectal NE tumors. In a patient with a pancreatic NE tumor (D172Y), the corresponding germline DNA showed the same mutation, suggesting that sporadic MEN1 syndrome was masked in this case. Somatic MEN1 gene mutations and deletions may play a crucial role in the tumorigenesis of a subset of foregut-derived NE tumors. Sporadic MEN1 syndrome may occur as a sporadic NE tumor of the pancreas.

Granulocytic sarcoma of the thymus in a nonleukaemic patient.

We report a case of granulocytic sarcoma arising from the thymus in a 17-year-old nonleukaemic patient. The patient presented with an anterior mediastinal tumour and underwent surgical resection. Histological examination showed a diffuse infiltrate of immature round cells in the thymus. Tumour cells were diffusely peroxidase positive, but naphthol AS-D chloroacetate esterase negative. Immunohistochemical staining revealed expression of CD34 and terminal deoxynucleotidyl transferase (TdT), but not of CD13 and CD33. Ultrastructurally, electron-dense or medium-density granules were present in the cytoplasm. Four months after successful autogenic bone marrow transplantation, pleural and pericardial fluid contained tumour cells with azurophilic granules, which expressed CD13 and CD33, but not CD34 and TdT. The patient died of the disease 18 months after clinical manifestation, but still without developing leukaemia. The granulocytic sarcoma in the present case may have originated from myeloid precursors in the thymus and remained within the extramedullary site despite the differentiation into a more committed myeloid lineage at the relapse.

Two cases of methotrexate induced lymphomas in rheumatoid arthritis: an association with increased serum IgE.

We describe 2 patients with rheumatoid arthritis (RA) in whom non-Hodgkin's lymphomas developed during low dose pulsed methotrexate (MTX) treatment. The tumors regressed after discontinuation of MTX with no additional treatment. Serum levels of IgE increased concomitantly with the development of lymphoma, and decreased along with the regression of the lymphoma in both patients. These 2 cases and a review of the literature suggest that measuring serum IgE may have a predictive value for monitoring lymphoma in patients with RA treated with MTX.

Polymerase chain reaction screening of immunoglobulin heavy chain and T cell receptor gamma gene rearrangements: a practical approach to molecular DNA analysis of non-Hodgkin's lymphoma in a surgical pathology laboratory.

Characterization of the clonality of non-Hodgkin's lymphoma (NHL) by the rearranged segments of immunoglobulin heavy chain (Ig(H)) or T cell receptor (TCR) genes is not only useful in the confirmation of the diagnosis but also for the future assessment of how a secondary lymphoma, such as a recurrence or another primary lymphoma, occurs. As a practical approach to obtaining and registering this information in a surgical pathology laboratory, FR3 and FR1 regions of Ig(H) gene and TCRgamma gene were concurrently amplified by polymerase chain reaction (PCR) using each pair of consensus primers and the same PCR protocol. Examined samples consisted of 134 primary NHL (phenotypically, 108 B cell and 26 T cell NHL), 19 reactive lymphadenopathies, as well as five secondary lymphomas whose primary lesions were included in this study. Among the primary NHL, the combined PCR analysis disclosed the clonality in 103 of 134 NHL (77%), by FR3 PCR in 77 B cell and two T cell NHL, by FR1 PCR in 59 B cell and one T cell NHL, and by TCRgamma PCR in 11 B cell and 17 of 26 T cell NHL, but in none of the reactive lymphadenopathies. Among the secondary lymphomas, the same pattern of PCR analysis was obtained in two cases (the durations between first and second lymphomas; 6 and 10 months), which suggested recurrence. In contrast, different results were obtained in three cases (17-37 months), which indicated another primary or emergence of the subclones. The results of Southern blot analysis were concordant with the PCR results of the first and the secondary lymphomas. Although the combined PCR analysis cannot replace Southern blot hybridization because of its lower detection rate, it can select those cases suitable for further Southern blot analysis thus reducing the number of unnecessary examinations by nearly 75%. This approach may also be useful in the comparative evaluation of primary and secondary lymphomas.

Higher frequency of Smad4 gene mutation in human colorectal cancer with distant metastasis.

We have previously detected an increased frequency of loss of heterozygosity (LOH) on chromosome 18q during progression of colorectal carcinomas. To clarify the target of 18qLOH, mutation of Smad4 and Smad2 genes was analysed in 176 colorectal tumors with different stages, including liver metastasis, from 111 sporadic, 52 familial adenomatous polyposis (FAP) and nine hereditary nonpolyposis colorectal cancer (HNPCC) patients. Mutation of other Smad gene families in the TGF-beta signaling pathway was also examined. Twenty-one Smad4 mutations and one Smad2 mutation were detected, whereas mutation of Smad3, 6 and 7 genes was not detected. Smad4 mutations included seven frameshift, one inframe deletion, four nonsense and nine missense mutations, 95% of which resulted in alteration of Smad4 protein regions included in homo-oligomer and hetero-oligomer formation. Frequencies of tumors with Smad4 mutation were 0/40 (0%) in adenoma, 4/39 (10%) in intramucosal carcinoma, 3/44 (7%) in primary invasive carcinoma without distant metastasis, 6/17 (35%) in primary invasive carcinoma with distant metastasis, and 11/36 (31%) in distant metastasis (metastatic/non-metastatic: P=0.006 approximately 0.01). Loss of the other allele was observed in 19 of 20 (95%) invasive and metastasized carcinomas with Smad4 mutations. In four cases both primary and metastasized carcinomas in the same patients showed the same mutations. The present results suggest that Smad4 gene is one of true targets of 18qLOH, and that its inactivation is involved in advanced stages, such as distant metastasis, in human colorectal carcinogenesis.

Pseudomyxoma retroperitonei.

We report a rare case of pseudomyxoma retroperitonei in a 58-year-old woman with a past history of severe appendicitis. The imaging showed a multicystic mass similar to pseudomyxoma peritonei, but the tumor was located in the retroperitoneal space.

Telomerase activity in gastrointestinal stromal tumors.

BACKGROUND: Telomerase activity has been observed in 80-90% of carcinomas derived from various organs. However, to the authors' knowledge this report is the first assessment of telomerase activity in gastrointestinal stromal tumors (GISTs). METHODS: Telomerase activity was analyzed by the telomerase repeat amplification protocol assay in 29 tumors from 26 patients (23 primary tumors from 22 patients, 1 pair of primary and metastatic tumors from 1 patient, and 4 metastatic tumors from 3 patients). Phenotypes, tumor cell proliferation, and overexpression of p53 protein were evaluated immunohistochemically. RESULTS: Seven of 24 primary tumors (29%) and 5 of 5 metastatic tumors (100%) showed telomerase activity. Telomerase activity positive (+) GISTs were significantly larger (P < 0.05) and showed a significantly higher rate of proliferation than telomerase activity negative (-) tumors (P < 0.0001). All telomerase activity (+) GISTs were classified histologically as high risk tumors. Conversely, 15 of the 17 telomerase (-) GISTs were classified histologically as low risk tumors (P < 0.0001). With regard to p53 immunoreactivity, two and seven telomerase activity (+) tumors showed diffuse and sporadic positivity, respectively, whereas only five telomerase activity (-) tumors showed only focal or sporadic positivity. Telomerase activity was correlated significantly with poor prognosis (P < 0.05) in the patients in whom the primary GISTs were evaluated (n = 23). CONCLUSIONS: Telomerase activity may be a useful marker for evaluating the malignant potential of GIST. A distinct subgroup of GISTs is a target for therapy with a telomerase inhibitor.

Neuroendocrine differentiation in thymic epithelial tumors with special reference to thymic carcinoma and atypical thymoma.

To determine the neuroendocrine (NE) features of thymic epithelial tumor, immunohistochemistry and electron microscopy studies were performed on eight NE tumors (thymic carcinoids) and 26 non-NE tumors (nine thymic carcinomas, five atypical thymomas, and 12 thymomas other than lymphocytic thymoma). Immunohistochemical studies were performed with antibodies against general markers for NE cells (synaptophysin, alpha subunit of a guanine nucleotide-binding protein, Go, and small-cell lung carcinoma cluster 1 antigen), and a broad panel of antibodies for hormonal substances. Thymic carcinoid showed synchronous diffuse immunoreactivity for the three NE markers and contained cells that were positive for a variety of hormonal products: human chorionic gonadotropin (hCG) alpha-subunit (eight of eight), hCG beta-subunit (three of eight), adrenocorticotropic hormone (ACTH) (three of eight), calcitonin (two of eight), calcitonin gene-related peptide (two of eight), and serotonin (one of eight). Conversely, although positivity for NE markers was neither synchronous nor diffuse in non-NE tumors, seven of nine thymic carcinomas, three of five atypical thymomas (focal or dispersed distribution), and none of the five thymomas were positive for at least two of these NE markers. A small number of neoplastic cells were positive for hCGalpha-subunit or ACTH in three thymic carcinomas and one atypical thymoma. Ultrastructurally, dense core granules (DCG) were much more frequent in thymic carcinoid, but several DCG-like granules were identified in 12 of 13 non-NE tumors with or without immunoexpression of NE markers. The presence of focal or dispersed NE cells in thymic carcinoma and atypical thymoma may reflect multidirectional differentiation within the tumor, which, like cytological atypia, epithelial CD5 expression, and lack of immature T cell infiltration, may be another feature of this group at thymic tumors.

Primary gastric T-cell lymphoma with and without human T-lymphotropic virus type 1.

BACKGROUND: Gastric T-cell lymphomas are rare, and their incidence and viral status have not yet been fully clarified. METHODS: Sixty-seven cases of surgically resected gastric lymphomas from city hospitals in Tokyo were evaluated. The surface phenotype was determined by immunohistochemistry, gene rearrangement by Southern blot hybridization, association with Epstein-Barr virus (EBV) by EBV-encoded small RNAs in situ hybridization, and the presence of human T-cell lymphotropic virus type 1 (HTLV-1) by serology, Southern blot hybridization, and polymerase chain reaction analysis. RESULTS: Five of the 67 cases were T-cell lymphoma (7%): 3 cases were HTLV-1 negative (-) and 2 were HTLV-1 positive (+). Systemic eosinophilia was observed in the three HTLV-1(-) gastric lymphomas. Neoplastic cells were morphologically similar in both groups, but a granulomatous reaction with marked eosinophilia was observed only in the two cases of HTLV-1(-) lymphoma. They also had characteristics of natural killer (NK) cell-like T-cell lymphoma, expressing NK markers and TCRgamma gene rearrangement. Positivity with HML-1 (specific for intestinal epithelial T-cells lymphoma was observed in one HTLV-1(+) lymphoma. The EBV gene was detected in only one case of B-cell lymphoma but not in any case of T-cell lymphoma. CONCLUSIONS: Gastric T-cell lymphoma occurs in 7% of gastric lymphomas in Japan and is comprised of HTLV-1-related lymphomas and lymphomas unrelated to HTLV-1, including NK cell-like lymphomas with eosinophilia.

Microsatellite instability and loss of heterozygosity in gastric lymphoma.

To evaluate the significance of microsatellite instability (MI) and loss of heterozygosity (LOH) in the development of gastric lymphoma, we examined 33 tissue-samples of 20 primary gastric B-cell lymphomas (6 low-grade lymphomas of mucosa-associated lymphoid tissue [MALT; 10 samples] and 14 diffuse large B-cell lymphomas [23 samples]). MI and LOH were evaluated at 13 microsatellite loci. In MALT lymphoma, four of six cases showed MI at one to two microsatellite loci (average 1.0 per case, 0.8 per sample), whereas in diffuse B-cell lymphoma, all samples showed MI at one to five microsatellite loci (average 2.4 per case, 2.7 per sample) (p < 0.05 and p = 0.0001). MI at the c-myc gene locus was most frequent in both types of gastric lymphomas (3 of 6 and 11 of 14 cases, respectively). Regional heterogeneity of the MI pattern was observed in two of four cases of MALT lymphoma and in four of five cases of diffuse B-cell lymphoma. On the other hand, LOH was observed only in one MALT lymphoma and in three diffuse B-cell lymphomas. Genetic instability may be an important mechanism for the development and progression of gastric lymphoma. Frequent MI at the c-myc locus might reflect an activated state and the importance of this gene in mucosal lymphocytes of chronic gastritis.