Ryoji Kushima

STAT6 immunohistochemistry is helpful in the diagnosis of solitary fibrous tumors.

Solitary fibrous tumor (SFT) is an uncommon fibroblastic neoplasm. Although histologic characteristics and frequent CD34 expression allow for an accurate diagnosis in the majority of SFT cases, a wide histologic spectrum and an occasional unexpected immunophenotype may pose diagnostic challenges. Molecular analyses have discovered that almost all SFTs harbor an NAB2-STAT6 fusion gene, which is considered specific to this tumor type. Recent studies have suggested that STAT6 immunohistochemistry is a reliable surrogate for detection of the fusion gene. Our aim was to validate these findings by examining a large number of SFT cases and a broad array of 30 different types of non-SFT tumors. A total of 49 SFTs with a range of histologic characteristics and 159 benign or malignant tumors that can mimic SFTs were retrieved and stained for STAT6. All 49 SFTs (100%) showed STAT6 expression that was restricted in the nucleus, mostly in a diffuse and strong manner, irrespective of the tumor sites and histologic patterns. The staining was uniform in most cases but was heterogenous in about 20% of the cases in which zonal staining attenuation was observed, likely reflecting variability in fixation or tissue ischemia. In contrast, only 4 non-SFT tumors (2.5%) exhibited weak nuclear STAT6 expression, whereas the remaining 155 cases showed no staining or often weak reactivity in both the cytoplasm and the nucleus. Therefore, nuclear STAT6 immunoreactivity is a highly sensitive and specific marker of SFTs and can be helpful when diagnosis is inconclusive by conventional methods.

Availability of CD10 Immunohistochemistry as a Marker of Breast Myoepithelial Cells on Paraffin Sections

CD10, also called common acute lymphoblastic leukemia antigen (CALLA), was recently found to be expressed in nonhematopoietic tissues. Although CD10 was also identified in human breast myoepithelial cells, its availability of immunohistochemistry on paraffin sections has not been examined so far. In the present study, we demonstrated CD10 immunohistochemically on paraffin sections of both normal and pathological breast tissues, comparing its staining patterns to those of smooth muscle actin (SMA), which is now commonly used to highlight myoepithelium. CD10 was consistently positive in normal breast myoepithelial cells. CD10 also clearly highlighted myoepithelial cells in intraductal papilloma, adenosis, ductal hyperplasia, fibroadenoma, and phyllodes tumor as well as SMA did. In atypical ductal hyperplasia and ductal carcinoma in situ, continuous, discontinuous, and totally negative stainings of both CD10 and SMA were noted, depending on foci of neoplastic cell nests. However, both stainings clearly demonstrated myoepithelial cells of cancerized acini, being useful in differentiating lobular cancerization from microinvasion. Because SMA was also positive in normal vessels and spindle-shaped stromal cells, CD10, which was negative in vessels, was useful in differentiating myoepithelial cells from thin vascular wall in intracystic lesions with delicate papillae. Although background staining of spindle-shaped stromal cells was also noted in CD10, the positive cell number was less, and the signal was weaker than that of SMA. The absence of myoepithelial cells in invasive ductal carcinomas was more clearly highlighted by CD10 than SMA. We concluded that CD10 could be another useful marker of breast myoepithelial cells on paraffin sections. Combination of CD10 and SMA will provide more sophisticated information about presence or absence of myoepithelial cells in confusing breast lesions.

MUC gene expression and histogenesis of adenocarcinoma of the stomach.

To elucidate the histogenesis of adenocarcinomas of the stomach, we examined MUC gene expression in gland‐forming intramucosal neoplastic lesions. Eighty tumors were histopathologically assigned to 1 of the following 3 groups based upon the Vienna classification: group A (low‐grade adenoma/dysplasia), group B (high‐grade adenoma/dysplasia) and group C (intramucosal carcinoma). Immunohistochemic staining was performed with monoclonal antibodies against MUC2 (goblet cell mucin), MUC5AC (gastric‐foveolar mucin), MUC6 (pyloric‐gland mucin) and CD10 (brush border). Ki‐67 staining was also carried out. An obvious difference existed in MUC gene expression between lesions in group A and those in groups B and C. The majority of group A lesions strongly expressed intestinal markers in which proliferating cell zones were formed but generally expressed no gastric markers, whereas more than 50% of groups B and C tumors expressed gastric markers. These findings suggest that group A lesions are of a stable intestinal phenotype, whereas those in groups B and C are phenotypically and genotypically unstable, indicating that the adenoma‐carcinoma sequence is not a major pathway, but instead that adenocarcinomas arise de novo.

Short- and long-term outcomes of endoscopic submucosal dissection for undifferentiated early gastric cancer.

BACKGROUND AND STUDY AIMS Intramucosal undifferentiated early gastric cancer (EGC) up to 2 cm in size without ulceration has been treated by endoscopic submucosal dissection (ESD) because the incidence of lymph node metastasis is negligible. The aim of this retrospective study was to clarify the short-term and long-term outcomes of ESD carried out to treat undifferentiated EGC. PATIENTS AND METHODS Between January 1999 and September 2011, 113 patients with poorly differentiated adenocarcinoma or signet ring cell carcinoma on preoperative biopsy underwent ESD. In 16 patients differentiated EGC had been diagnosed after the ESD and these patients were excluded from the study. Short-term outcomes were evaluated in the remaining 97 patients with undifferentiated EGC, and long-term outcomes analyzed in the 79 patients with undifferentiated EGC who had undergone ESD between 1999 and 2008. RESULTS En bloc and R0 resection were achieved in 99.0 % and 90.7 % of patients, respectively. Median procedure time was 45 minutes. Postoperative bleeding, perforation during the procedure, and delayed perforation were noted in 4.1 %, 3.1 %, and 1.0 % respectively. Curative resection was achieved in 63.9 %. Additional surgery was performed in 21 of 35 patients in whom resection was noncurative: one (4.8 %) had local residual tumor and two (9.5 %) had lymph node metastases. Of the 46 /79 patients in the long-term outcome group who had curative resection, none had local recurrence or lymph node or distant metastasis during a median follow-up of 76.4 months. The 5-year overall mortality rate after curative resection was 7.0 %, and no patient died of gastric cancer. CONCLUSIONS ESD for undifferentiated EGC can achieve curative resection with an excellent 5-year mortality rate.

Periostin is down-regulated in high grade human bladder cancers and suppresses in vitro cell invasiveness and in vivo metastasis of cancer cells

We have previously reported that expression of periostin mRNA is markedly reduced in a variety of human cancer cell lines, suggesting that downregulation of periostin mRNA expression is correlated with the development of human cancers. In our study, to clarify the role of the periostin in human bladder carcinogenesis, we examined the expression of periostin mRNA in normal bladder tissues, bladder cancer tissues and bladder cancer cell lines by Northern blot analysis and RT‐PCR analysis. Although the expression of periostin mRNA was detected in 100% (5/5) of normal bladder tissues, it was not detected in 3 human bladder cancer cell lines examined. It was also detected in 81.8% (9/11) of grade 1, 40.0% (4/10) of grade 2 and 33.3% (4/12) of grade 3 bladder cancer tissues, indicating that downregulation of periostin mRNA is significantly related to higher grade bladder cancer (p<0.05). To assess the tumor suppressor function of periostin, we investigated the ability of periostin gene to suppress malignant phenotypes of a bladder cancer cell line, SBT31A. Ectopic expression of periostin gene by a retrovirus vector suppressed in vitro cell invasiveness of the bladder cancer cells without affecting cell proliferation and tumor growth in nude mice. Periostin also suppressed in vivo lung metastasis of the mouse melanoma cell line, B16–F10. Mutational analysis revealed that the C‐terminal region of periostin was sufficient to suppress cell invasiveness and metastasis of the cancer cells. Periostin may play a role as a suppressor of invasion and metastasis in the progression of human bladder cancers.

Histogenesis and characteristics of gastric-type adenocarcinomas in the stomach

The characteristics and histogenesis of gastric-type adenocarcinomas were studied for endoscopically removed hyperplastic polyps and intramucosal cancers found in surgically resected stomachs (m-cancers). Among 421 hyperplastic polyps, 14 differentiated-type carcinomas were found (HP-cancer). Eleven (78.6%) of these lesions were gastric-type adenocarcinomas. Out of 65 m-cancers, 22 were undifferentiated-type carcinomas and 43 were differentiated-type carcinomas, the latter being classified into 10 gastric-type adenocarcinomas (23.2%) and 13 intestinal-type adenocarcinomas: the remaining 20 were of mixed gastric and intestinal type. The mean age of the gastric-type adenocarcinoma patients did not differ from that of patients with other differentiated-type carcinomas. No appreciable signs of intestinal metaplasia were noted in HP-cancer polyps. In m-cancers, the degree of intestinal metaplasia of the surrounding mucosa of gastric-type adenocarcinomas tended to be lower than in the other differentiated-type carcinomas, indicating a weak relationship between the histogenesis of gastric-type adenocarcinomas and intestinal metaplasia. Studies by PCNA (proliferating cell nuclear antigen) immunohistochemistry, showed that in over half of the gastric-type adenocarcinoma cases PCNA-positive cells tended to be localized within tumor tissues. In addition, point mutations of the c-Ki-ras gene were detected in 1 gastric-type adenocarcinoma and 2 intestinal-type adenocarcinomas, suggesting the occurence of a common genetic abnormality.

Multiple IgG4‐related sclerosing lesions in the maxillary sinus, parotid gland and nasal septum

IgG4‐related sclerosing disease is recognized as a distinct clinicopathological entity. It is well known that this disease can occur in the salivary, lacrimal and pituitary glands, in the head and neck region. The nasal cavity is an extremely rare site of involvement of IgG4‐related sclerosing disease. Herein is reported a case of multiple IgG4‐related sclerosing lesions in the maxillary sinus, parotid gland and nasal septum. A 73‐year‐old Japanese man presented with nasal obstruction and tumors of the right maxillary sinus and parotid gland were detected, after which resections of these tumors were performed. One year after the last surgery, he noted swelling of the nasal septum, and the tumor was resected. These three tumors had similar histopathology, such as conspicuous fibrosclerotic changes with dense lymphoplasmacytic infiltration and occasional obliterative phlebitis. Immunohistochemistry indicated abundant IgG4‐positive plasma cell infiltration and high ratios of IgG4‐positive/IgG‐positive plasma cells (>70%) in all three lesions. The diagnosis of multiple IgG4‐related sclerosing lesions was made. The present case suggests that IgG4‐related sclerosing lesion can occur in the maxillary sinus and nasal septum, and represents an extension of the spectrum of IgG4‐related sclerosing disease.

Gastric-type well-differentiated adenocarcinoma and pyloric gland adenoma of the stomach

Since 1985, when gastric-type well-differentiated adenocarcinomas were demonstrated in hyperplastic polyps of the stomach, we have studied phenotypic expression in gastrointestinal epithelial lesions. The recent discovery of MUC genes coding core proteins of mucin has improved research on the phenotypic expression of gastrointestinal neoplasms. The disease entity of gastric-type well-differentiated adenocarcinoma has recently been accepted, especially in Japan and Europe. This entity has often become a clinicopathological subject of discussion, because its biological behavior is possibly highly malignant, in spite of the difficulty in making endoscopic and histopathological diagnoses. Even under these circumstances, the term “gastric adenoma” usually means flat adenoma of the intestinal type. Gastric-type adenomas have been regarded as exceptional until recently. Although gastric-type adenomas could theoretically be classified into foveolar type and pyloric-gland type, foveolar-type adenoma is, in practice, difficult to distinguish from gastric-foveolar-type adenocarcinoma. In 2003, we first reported systematic clinicopathological analyses of pyloric gland adenoma, demonstrating its unstable and precancerous nature. In this article, we review and discuss the clinicopathological and molecular pathological aspects of gastric-type well-differentiated adenocarcinomas and pyloric gland adenomas, mainly based on our published and unpublished data.

Frequent GNAS mutations in low-grade appendiceal mucinous neoplasms

Background:The molecular basis for the development of appendiceal mucinous tumours, which can be a cause of pseudomyxoma peritonei, remains largely unknown.Methods:Thirty-five appendiceal mucinous neoplasms were analysed for GNAS and KRAS mutations. A functional analysis of mutant GNAS was performed using a colorectal cancer cell line.Results:A mutational analysis identified activating GNAS mutations in 16 of 32 low-grade appendiceal mucinous neoplasms (LAMNs) but in none of three mucinous adenocarcinomas (MACs). KRAS mutations were found in 30 LAMNs and in all MACs. We additionally analysed a total of 186 extra-appendiceal mucinous tumours and found that GNAS mutations were highly prevalent in intraductal papillary mucinous tumours of the pancreas (88%) but were rare or absent in mucinous tumours of the colorectum, ovary, lung and breast (0–9%). The prevalence of KRAS mutations was quite variable among the tumours. The introduction of the mutant GNAS into a colorectal cancer cell line markedly induced MUC2 and MUC5AC expression, but did not promote cell growth either in vitro or in vivo.Conclusion:Activating GNAS mutations are a frequent and characteristic genetic abnormality of LAMN. Mutant GNAS might play a direct role in the prominent mucin production that is a hallmark of LAMN.

Frequent GNAS and KRAS mutations in pyloric gland adenoma of the stomach and duodenum

Gastric and duodenal adenomas exhibit a significant morphological and phenotypical diversity and are classified into intestinal‐type, foveolar‐type and pyloric gland adenomas. We analysed the mutations in GNAS, KRAS, BRAF and CTNNB1 and the expressions of mismatch repair (MMR) proteins in 80 gastric and 32 duodenal adenomas with histologically distinct subtypes, as well as in 71 gastric adenocarcinomas. Activating GNAS mutations were found in 22 of the 35 pyloric gland adenomas (PGAs; 63%) but in none of the foveolar‐type or intestinal‐type adenomas or the adenocarcinomas. Fourteen PGAs (41%), two foveolar‐type adenomas (9%), five intestinal‐type adenomas (9%) and one adenocarcinoma (1%) had KRAS mutations. BRAF mutations were absent in all the adenomas and adenocarcinomas that were examined. CTNNB1 mutations were only found in two intestinal‐type adenomas (4%). Notably, 13 of the 14 KRAS‐mutated gastric and duodenal PGAs had concurrent GNAS mutations. The loss of the MMR proteins, which is indicative of microsatellite instability, was observed in one PGA (3%), 12 foveolar‐type adenomas (52%), one intestinal‐type adenoma (2%) and five adenocarcinomas (7%). These observations indicate that each histological subtype of gastric and duodenal adenomas has a distinct genetic background. In particular, the present study identified the frequent presence of activating GNAS mutations, which are often associated with KRAS mutations, as a characteristic genetic feature of PGAs of the stomach and duodenum.