Transmembrane mucin MUC13 distinguishes intraductal papillary mucinous neoplasms from non-mucinous cysts and is associated with high-risk lesions.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMN) are currently managed based on imaging characteristics and cyst fluid sampling. This study was designed to determine if MUC13, a glycoprotein aberrantly overexpressed in pancreatic adenocarcinoma, might aid in distinguishing high-risk lesions (high grade dysplasia/invasive disease) from low-grade lesions. METHODS: MUC13 immunohistochemical staining was performed on surgically resected formalin-fixed tissue specimens from 49 IPMNs and 23 non-mucinous cysts. Membranous MUC13 expression was measured by H-score, which quantifies staining intensity and the percentage of cells involved (range 0-300). RESULTS: MUC13 expression was detected in all IPMNs and was significantly greater than in non-mucinous cysts (median 210 vs 40, p < 0.001). MUC13 expression was similar among main (n = 26), branch (n = 15), and mixed (n = 8) duct lesions (median 210, 200, 225, respectively). The highest expression was observed in tumors with intestinal and pancreatobiliary histologic features (both median 225) and the lowest in gastric type lesions (median 200). MUC13 expression was significantly greater in high-risk lesions (n = 21) compared to those with low-grade dysplasia (n = 28) (median 250 vs 195, p < 0.001). CONCLUSION: MUC13 expression was significantly greater in high-risk IPMNs in this analysis. The preoperative assessment of MUC13 in cyst fluid samples warrants further investigation.

TERT promoter mutations and prognosis in solitary fibrous tumor.

Solitary fibrous tumor is a mesenchymal neoplasm exhibiting a broad spectrum of biological behavior and harboring the NAB2-STAT6 fusion. Clinicopathologic parameters are currently used in risk-prediction models for solitary fibrous tumor, but the molecular determinants of malignancy in solitary fibrous tumors remain unknown. We proposed that the activation of telomere maintenance pathways confers a perpetual malignant phenotype to these tumors. Therefore, we investigated telomerase reverse transcriptase (TERT) reactivation induced by promoter mutations as a potential molecular mechanism for aggressive clinical behavior in solitary fibrous tumor. The retrospective study included tumor samples from 94 patients with solitary fibrous tumor (31 thoracic and 63 extra-thoracic). Follow-up information was available for 68 patients (median, 46 months). TERT promoter mutation analysis was performed by PCR and Sanger sequencing, and TERT mRNA expression was assessed by real-time quantitative reverse transcription PCR. Patients were stratified into clinicopathologic subgroups (high-risk (n=20), moderate-risk (n=28), and low-risk (n=46)) according to the risk-stratification model proposed by Demicco et al. TERT promoter mutations were identified in 26 of 94 (28%) solitary fibrous tumors: -124C>T in 23 tumors (88%), -124C>A in 1 tumor (4%), and -146C>T in 2 tumors (8%). Real-time quantitative reverse transcription PCR revealed that TERT mRNA expression was higher in all solitary fibrous tumors with the mutant TERT promoter than those with the wild-type TERT promoter. TERT promoter mutations were strongly associated with high-risk clinicopathologic characteristics and outcome. An adverse event (relapse, death) occurred in 16 of 68 (24%) patients, 12 with solitary fibrous tumors with TERT promoter mutations and 4 with the wild-type TERT promoter. TERT promoter mutations were strongly associated with older age (P=0.006), larger tumor size (P=0.000002), higher risk classifications (P=2.9 × 10-9), and a worse event-free survival (P=0.0082). Thus, TERT promoter mutations in solitary fibrous tumor influence gene expression and are associated with adverse patient outcome. Integrating TERT promoter mutational status with existing multivariable risk-prediction models might improve risk prediction in patients with solitary fibrous tumor.

Over expression of insulin-like growth factor binding protein 3 in clear cell renal cell carcinoma.

PURPOSE: We recently reported that IGFBP-3 (insulin-like growth factor binding protein 3) is one of the top genes that are over expressed in clear cell renal cell carcinoma. We further investigated IGFBP-3 expression in renal tumors using gene expression microarrays, immunohistochemistry and Western blotting. MATERIALS AND METHODS: A total of 70 renal neoplasms were subjected to gene expression microarrays using gene chips containing 21,632 cDNA clones. IGFBP-3 expression was measured in each renal epithelial neoplasm. In addition, we performed immunohistochemistry for IGFBP-3 in 127 renal epithelial tumors, including 58 clear cell renal cell carcinomas. Moreover, IGFBP-3 staining intensity was evaluated to determine whether there was a correlation with Fuhrman grade. Lastly, Western blot was performed to confirm IGFBP-3 levels. RESULTS: On microarray analysis of 70 renal neoplasms IGFBP-3 mRNA was increased in 63% of clear cell renal cell carcinomas (27 of 43) but in only 4% of other renal tumors (1 of 24). On immunohistochemistry 74% of clear cell renal cell carcinomas (43 of 58) showed IGFBP-3 immunoreactivity compared to only 9% of other renal neoplasms (6 of 69). High grade (Fuhrman grades 3 and 4) clear cell renal cell carcinomas showed higher IGFBP-3 staining intensity than low grade ones (15 of 17 vs 8 of 41). Western blot confirmed immunohistochemistry findings with the detection of high IGFBP-3 in clear cell renal cell carcinoma but not in other types of kidney tumors. CONCLUSIONS: With a combination of cDNA microarrays, Western blot and immunohistochemistry we confirmed that IGFBP-3 is a marker for clear cell renal cell carcinoma. Furthermore, higher IGFBP-3 expression was associated with higher Fuhrman grade.

Biatrial primary cardiac paraganglioma: a rare finding.

The majority of primary cardiac tumors are benign; of these tumors, cardiac paragangliomas are among the rarest. We report a case of biatrial cardiac paraganglioma discovered during workup for palpitations and fatigue. The tumor involved the interatrial septum, with a lobulated portion protruding through the foramen ovale into the right atrium. The tumor was successfully excised, leading to uneventful recovery.

Follicular pancreatitis: a distinct form of chronic pancreatitis-an additional mimic of pancreatic neoplasms.

Follicular pancreatitis is a recently described variant of chronic pancreatitis characterized clinically by the formation of a discrete pancreatic mass and histologically by the presence of florid lymphoid aggregates with reactive germinal centers. Our aim was to study the clinical and histologic features of follicular pancreatitis, as well as to critically examine potential overlap with autoimmune pancreatitis. Immunohistochemistry for Bcl-2, CD21, κ and λ light chains as well as IgG4 and IgG were performed. We found a total of 6 patients (male-female ratio, 2:1; mean age, 57 years) who fulfilled the diagnosis of follicular pancreatitis in our institutions. Four had an incidental diagnosis, while two presented with abdominal pain, fatigue, and elevated liver enzymes. On imaging, 3 patients had a discrete solid mass, whereas 2 cases showed a dilated main pancreatic duct, mimicking an intraductal pancreatic mucinous neoplasm on imaging. One patient had a lesion in the intra-pancreatic portion of the common bile duct. On histopathology, all cases showed numerous lymphoid follicles with Bcl-2-negative germinal centers either in a periductal or in a more diffuse (periductal and intra-parenchymal) fashion, but without attendant storiform fibrosis, obliterative phlebitis, or granulocytic epithelial lesions. IgG4-to-IgG ratio was <40% in 5 cases. A comparison cohort revealed germinal centers in 25% of type 1 autoimmune pancreatitis and 2% of type 2 autoimmune pancreatitis cases, but none were periductal in location. In conclusion, follicular pancreatitis, an under-recognized mimic of pancreatic neoplasms is characterized by intrapancreatic lymphoid follicles with reactive germinal centers.

Capillary hemangioblastoma of soft tissue: report of a case and review of the literature.

Capillary hemangioblastoma (CH) is a tumor of unknown histogenesis that arises primarily in the posterior cranial fossa, either as a sporadic event or in association with von Hippel-Lindau disease. To date, only 6 examples of a tumor with morphological features of CH arising in the somatic soft tissues have been documented in case reports and small series, and 3 of these tumors were associated with a peripheral nerve. Herein, we report a case of CH arising in the gastrocnemius muscle and not associated with a peripheral nerve in a 53-year-old woman with no clinical stigmata or family history of von Hippel-Lindau disease.

C-kit expression in renal oncocytomas and chromophobe renal cell carcinomas.

C- kit encodes the membrane-bound tyrosine kinase KIT, whose expression has been identified in several types of human neoplasms. Recently, KIT has been reported to be a marker for chromophobe renal cell carcinoma (RCC) and renal angiomyolipoma. However, expression of this molecule has not been adequately studied in other renal tumors, particularly oncocytoma, which may morphologically resemble chromophobe RCC. In this study, we analyzed c- kit messenger RNA (mRNA) levels in 17 chromophobe RCCs and 20 renal oncocytomas obtained from complementary DNA (cDNA) microarrays. Furthermore, comprehensive immunohistochemical analysis of KIT protein using a monoclonal antibody was performed in 226 renal tumors including chromophobe RCC (n=40), oncocytoma (n=41), clear-cell RCC (n=40), renal angiomyolipoma (n=29), and papillary RCC (n=21) on tissue microarrays (TMAs) and was compared with immunostaining results from 25 chromophobe RCCs and 30 oncocytomas using standard sections. The staining intensity was semiquantitatively graded on a 3-tier scoring system. All chromophobe RCCs and oncocytomas showed significant overexpression of c- kit mRNA. The average increase of mRNA compared with normal kidney tissue was 7.4-fold for chromophobe RCCs and 7.4-fold for oncocytomas. Immunohistochemical expression of KIT was found in most chromophobe RCCs (95% in TMAs and 96% in conventional sections) and oncocytomas (88% in TMAs and 100% in conventional sections) but was infrequently observed in renal angiomyolipomas (17%), papillary RCCs (5%), and clear-cell RCCs (3%). Furthermore, the average KIT immunoreactivity in TMAs was stronger in chromophobe RCC (1.93) and oncocytoma (2.07) than in other subtypes of renal tumors tested, including angiomyolipomas (0.17), papillary RCCs (0.05), and clear-cell RCCs (0.03). In conclusion, we found a significant elevation of c- kit mRNA by cDNA expression microarrays and overexpression of KIT protein by immunohistochemistry not only in chromophobe RCCs but also in oncocytomas. In contrast, immunohistochemical expression of KIT was not detected in most other types of renal cell tumors evaluated. The differential expression of c- kit in these renal tumors may have diagnostic and therapeutic implications.

Hyalinizing cholecystitis with features of immunoglobulin G4-related disease-coincidence or an unrecognized association? A case report.

Hyalinizing cholecystitis (HC) is a recently described rare subtype of chronic cholecystitis characterized by dense, paucicellular collagenous transmural fibrosis, which usually replaces the mucosa and muscularis propria. Immunoglobulin (Ig)G4-associated cholecystitis is also a newly described cholecystitis variant characterized by transmural or extramural lymphoplasmacytic inflammation, lymphoid follicles, storiform fibrosis, phlebitis, and increased tissue IgG4-positive plasma cells. We describe a case of cholecystitis in an elderly white man who harbored features of both HC and IgG4-associated cholecystitis. In retrospect, the patient also had a significantly elevated serum IgG4 level. To the best of our knowledge, an association between HC and IgG4-related disease has not been previously described in the literature. Although not entirely conclusive, our observations raise the possibility that some cases of HC represent the end stage of IgG4-related disease.

Expression of RON Proto-oncogene in Renal Oncocytoma and Chromophobe Renal Cell Carcinoma.

Recently, it was reported that RON proto-oncogene, encoding a receptor tyrosine kinase, was strongly expressed in renal oncocytomas but not in any renal cell carcinomas, including 5 chromophobe renal cell carcinomas, which morphologically resemble oncocytomas. To determine its diagnostic value, we studied Ron protein expression by immunohistochemistry in a larger number of renal cell neoplasms with emphasis on chromophobe renal cell carcinomas. Tissue microarrays containing 141 renal cell neoplasms, including 55 oncocytomas and 52 chromophobe renal cell carcinomas, were constructed. In addition, conventional sections from 15 cases of oncocytoma and 5 cases of chromophobe renal cell carcinoma were analyzed. Immunohistochemistry was carried out with a monoclonal mouse anti-human Ron-alpha antibody. Staining intensity was scored on a 0 to 3 scale. Ninety-nine percent of oncocytomas (69 of 70) and 96% of chromophobe renal cell carcinomas (55 of 57) showed moderate to strong, diffuse cytoplasmic Ron immunoreactivity with intensities > or =2, while only 17% of other renal cell carcinoma subtypes stained with intensities > or =2. Our study indicates that Ron immunostaining cannot be used to distinguish oncocytoma from chromophobe renal cell carcinoma.

Analysis of alpha-methylacyl-CoA racemase (P504S) expression in high-grade prostatic intraepithelial neoplasia.

Alpha-methylacyl-CoA racemase (AMACR), also known as P504S, is a recently identified molecular marker for prostate cancer. The expression of AMACR/P504S has also been observed in high-grade prostatic intraepithelial neoplasia (PIN), a precursor lesion of prostate cancer. However, a detailed study focusing on the analysis of AMACR/P504S expression in high-grade PIN has not been performed. In this study, we analyzed AMACR/P504S expression by immunohistochemistry in 3954 prostatic ducts and acini with high-grade PIN from 140 prostatectomy specimens. AMACR/P504S immunoreactivity was measured as negative (0), weakly positive (+1), moderately positive (+2), and strongly positive (+3). AMACR/P504S immunoreactivity was detected in 90.0% (126/140) of high-grade PIN cases, although only 41.5% (1642/3954) of prostatic glands involved by PIN showed AMACR/P504S immunoreactivity. A significantly higher AMACR/P504S-positive rate (56.0%) was found in isolated high-grade PIN glands adjacent to cancer (distance less than 5 mm) compared with those away from cancer (distance more than 5 mm; 14%, P < 0.0001). High-grade PIN glands adjacent to cancer also showed a higher (P < 0.0004) AMACR/P504S intensity (1.62) than did those away from cancer (1.11). Our results suggest that PIN strongly positive for AMACR/P504S might be more closely associated with cancer than PIN negative or weakly positive for AMACR/P504S. This study provides additional evidence to link high-grade PIN as a precursor lesion to prostatic adenocarcinoma.

Atypical vascular lesions after surgery and radiation of the breast: a clinicopathologic study of 32 cases analyzing histologic heterogeneity and association with angiosarcoma.

We report the clinicopathologic study of 32 cases of atypical vascular lesions (AVLs) after surgery and radiation of the breast, which were referred to us in consultation over a 17-year period. The patients, all women, ranged in age from 41 to 95 years (mean 61 y). The lesions developed within the radiation field from 1 to 12 years (median 6.0 y) after therapy. They occurred as one (n=18) or more (n=10) flesh-colored papules or erythematous patches/plaques ranging in size from 1 to 60 mm (mean 8.0 mm, median 4.0 mm). Tumors could be divided into 2 histologic types: a lymphatic type (LT) (n=22) and a vascular type (VT) (n=10). LT AVLs consisted predominantly of thin-walled, variably anastomosing lymphatic vessels that were usually confined to the superficial dermis but occasionally extended into the deep dermis and even subcutis. The VT (n=10) typically consisted of small, irregularly dispersed, often blood-filled, pericyte-invested, capillary-sized vessels involving the superficial or deep dermis. VTs were often associated with extravasated erythrocytes, hemosiderin, and a surrounding minor LT component. In 4 cases, endothelial atypia, consisting of nuclear and nucleolar enlargement, was noted. Follow-up of 21 patients with LT AVLs (1 to 106 mo; mean 47 mo) disclosed recurrence/additional lesions in 6, all of whom had additional surgery. Of the 21 patients, 17 are alive without disease, 1 is alive with disease, 1 died of breast carcinoma, 1 died of unknown causes, and 1 showed progressive histologic changes in the AVLs over a period of 5 years resulting in a well-differentiated angiosarcoma. Follow-up in 8 patients with VT AVL (2 to 181 mo; mean 40 mo) disclosed that 6 were alive and well, but 2 of the 4 patients whose lesions displayed endothelial atypia had additional complications. One patient underwent a mastectomy that revealed extensive residual AVL and the second developed a high-grade angiosarcoma after 14 months. We conclude that AVLs encompass a wider spectrum of changes than previously appreciated, ranging from superficial lymphatic proliferations to more complex lymphatic and capillary vascular lesions. There seems to be an association of AVL with angiosarcoma that differs depending on the histologic features, with the VT AVLs having the higher risk. In the 2 patients who developed angiosarcoma, morphologic evidence suggested AVLs to be a precursor rather than simply a risk factor. Future outcome and management studies should take into account these differences.

Benign metastasizing leiomyoma: clonality, telomere length and clinicopathologic analysis.

Benign metastasizing leiomyoma is a rare condition affecting women with a history of uterine leiomyomata and is characterized by multiple histologically benign pulmonary smooth muscle tumors. Speculations on its pathogenesis include a benign uterine leiomyoma colonizing the lung, a metastatic low-grade uterine leiomyosarcoma, and primary pulmonary leiomyomatosis. To elucidate its pathogenesis, we analyzed the clinical, pathological and immunohistochemical features, clonality, and telomere length of multiple lung and uterine tumors in three patients with benign metastasizing leiomyoma. In all cases, pulmonary tumors had benign histology and immunohistochemical profiles (estrogen receptor positive, progesterone receptor positive, and very low proliferative index) identical to uterine leiomyoma. In eight tumors from three patients, clonality was assessed by analyzing the variable length of the polymorphic CAG repeat sequence within the human androgen receptor gene. In the two informative patients pulmonary and uterine tumors showed identical patterns of androgen receptor allelic inactivation, indicating that they were clonal. The telomere length measured by fluorescence in situ hybridization in pulmonary leiomyomas of all three patients were either long or very long and were identical to the uterine counterparts, indicating significant telomere shortening is not a crucial step for developing metastases. Our evidence supports the notion that benign metastasizing leiomyoma is clonally derived from benign-appearing uterine leiomyomas.