Utilizing PTEN immunohistochemistry as a screening test for Cowden syndrome

OBJECTIVES

Cowden syndrome (CS) is a multisystem disease with an elevated lifetime risk of internal malignancy. We aim to assess the role of PTEN immunostain as a screening test for CS in a variety of common CS-associated neoplasms, with a particular focus on cutaneous tumors.

METHODS

We retrospectively searched for patients meeting criteria for CS and/or demonstrating germline PTEN mutation from 2008 to 2022. We then performed PTEN immunostains on tumors of these patients as well as control cases.

RESULTS

Our study included 30 patients with CS who had a total of 25 CS-associated malignancies (13 thyroid, 8 breast, and 4 endometrial carcinomas). Specifically, there were 11 patients with biopsy-confirmed CS-associated cutaneous neoplasms, including 1 patient with multiple trichilemmomas and 3 with multiple sclerotic fibromas. In total, 45 CS-associated tumors (6 trichilemmomas, 7 sclerotic fibromas, 5 thyroid carcinomas, 18 adenomatous thyroid nodules, 6 breast carcinomas, and 3 endometrial carcinomas) and 31 non-CS cases (9 trichilemmomas, 5 sclerotic fibromas, 8 adenomatous thyroid nodules, and 3 thyroid, 3 breast, and 3 endometrial carcinomas) were available for PTEN immunohistochemical staining. PTEN expression was lost in 43 (96%) of 45 CS-associated lesions and retained in 30 (97%) of 31 sporadic tumors. The overall sensitivity and specificity of PTEN loss of expression as a screening test for CS were 96% and 97%, respectively.

CONCLUSIONS

PTEN immunohistochemistry on CS-associated tumors, especially trichilemmomas, can serve as a readily accessible and cost-effective screening test for CS.

Diagnostic Value of MAML2 Rearrangements in Mucoepidermoid Carcinoma

Mucoepidermoid carcinoma (MEC) is often seen in salivary glands and can harbor MAML2 translocations (MAML2+). The translocation status has diagnostic utility as an objective confirmation of the MEC diagnosis, for example, when distinction from the more aggressive adenosquamous carcinoma (ASC) is not straightforward. To assess the diagnostic relevance of MAML2, we examined our 5-year experience in prospective testing of 8106 solid tumors using RNA-seq panel testing in combinations with a two-round Delphi-based scenario survey. The prevalence of MAML2+ across all tumors was 0.28% (n = 23/8106) and the majority of MAML2+ cases were found in head and neck tumors (78.3%), where the overall prevalence was 5.9% (n = 18/307). The sensitivity of MAML2 for MEC was 60% and most cases (80%) were submitted for diagnostic confirmation; in 24% of cases, the MAML2 results changed the working diagnosis. An independent survey of 15 experts showed relative importance indexes of 0.8 and 0.65 for "confirmatory MAML2 testing" in suspected MEC and ASC, respectively. Real-world evidence confirmed that the added value of MAML2 is a composite of an imperfect confirmation test for MEC and a highly specific exclusion tool for the diagnosis of ASC. Real-world evidence can help move a rare molecular-genetic biomarker from an emerging tool to the clinic.

Adamantinoma-like Ewing Sarcoma of the Salivary Glands: A Newly Recognized Mimicker of Basaloid Salivary Carcinomas

Adamantinoma-like Ewing sarcoma (ALES) is a rare tumor that demonstrates the EWSR1-FLI1 translocation characteristic of Ewing sarcoma despite overt epithelial differentiation including diffuse expression of cytokeratins and p40. Most cases of ALES described to date have occurred in the head and neck where they can mimic a wide range of small round blue cell tumors. Because distinguishing ALES from basaloid salivary gland carcinomas can be particularly difficult, we analyzed a series of 10 ALESs that occurred in the salivary glands with the aim of identifying features that allow for better recognition of this entity. The salivary ALESs included 8 parotid gland and 2 submandibular gland tumors in patients ranging from 32 to 77 years (mean: 52 y). Nine were initially misclassified as various epithelial neoplasms. Although these tumors displayed the basaloid cytology, rosette formation, infiltrative growth, and nuclear monotony characteristic of ALES, peripheral palisading and overt keratinization were relatively rare in this site. Salivary ALESs not only displayed positivity for AE1/AE3, p40, and CD99, but also demonstrated a higher proportion of synaptophysin reactivity than has been reported for nonsalivary ALESs. These morphologic and immunohistochemical findings make ALES susceptible to misclassification as various other tumors including basal cell adenocarcinoma, adenoid cystic carcinoma, squamous cell carcinoma, NUT carcinoma, large cell neuroendocrine carcinoma and myoepithelial carcinoma. Nevertheless, monotonous cytology despite highly infiltrative growth and concomitant positivity for p40 and synaptophysin can provide important clues for consideration of ALES, and identification of the defining EWSR1-FLI1 translocations can confirm the diagnosis.

Alpha-tocopherol in intravenous lipid emulsions imparts hepatic protection in a murine model of hepatosteatosis induced by the enteral administration of a parenteral nutrition solution

Intestinal failure-associated liver disease (IFALD) is a risk of parenteral nutrition (PN)-dependence. Intravenous soybean oil-based parenteral fat can exacerbate the risk of IFALD while intravenous fish oil can minimize its progression, yet the mechanisms by which soybean oil harms and fish oil protects the liver are uncertain. Properties that differentiate soybean and fish oils include α-tocopherol and phytosterol content. Soybean oil is rich in phytosterols and contains little α-tocopherol. Fish oil contains abundant α-tocopherol and little phytosterols. This study tested whether α-tocopherol confers hepatoprotective properties while phytosterols confer hepatotoxicity to intravenous fat emulsions. Utilizing emulsions formulated in the laboratory, a soybean oil emulsion (SO) failed to protect from hepatosteatosis in mice administered a PN solution enterally. An emulsion of soybean oil containing α-tocopherol (SO+AT) preserved normal hepatic architecture. A fish oil emulsion (FO) and an emulsion of fish oil containing phytosterols (FO+P) protected from steatosis in this model. Expression of hepatic acetyl CoA carboxylase (ACC) and peroxisome proliferator-activated receptor gamma (PPARγ), was increased in animals administered SO. ACC and PPARγ levels were comparable to chow-fed controls in animals receiving SO+AT, FO, and FO+P. This study suggests a hepatoprotective role for α-tocopherol in liver injury induced by the enteral administration of a parenteral nutrition solution. Phytosterols do not appear to compromise the hepatoprotective effects of fish oil.

Fish oil protects the liver from parenteral nutrition-induced injury via GPR120-mediated PPARγ signaling

Intravenous fish oil lipid emulsions (FOLE) can prevent parenteral nutrition (PN)-induced liver injury in murine models and reverse PN-induced cholestasis in pediatric patients. However, the mechanisms by which fish oil protects the liver are incompletely characterized. Fish oil is rich in omega-3 fatty acids, which are ligands for the G-protein coupled receptor 120 (GPR120), expressed on hepatic Kupffer cells. This study tested the hypothesis that FOLE protects the liver from PN-induced injury through GPR120 signaling. Utilizing a previously described murine model of PN-induced liver injury in which mice develop steatosis in response to an oral parenteral nutrition diet, FOLE was able to preserve normal hepatic architecture in wild type mice, but not in congenic GPR120 knockout (gpr120-/-) mice. To further characterize the requirement of intact GPR120 for FOLE-mediated hepatic protection, gene expression profiles of key regulators of fat metabolism were measured. PPARγ was identified as a gene that is up-regulated by the PN diet and normalized with the addition of FOLE in wild type, but not in gpr120-/- mice. This was confirmed at the protein expression level. A PPARγ expression array further identified CD36 and SCD1, both down-stream effectors of PPARγ, to be up-regulated in PN-fed wild type mice yet normalized upon FOLE administration in wild type but not in gpr120-/- mice. Together, these results suggest that FOLE protects the liver, in part, through activation of GPR120 and the downstream effectors PPARγ and CD36. Identification of key genetic determinants of FOLE-mediated hepatic protection may provide targets for small molecule-based hepatic protection strategies.

Clinically Integrated Molecular Diagnostics in Adenoid Cystic Carcinoma

Adenoid cystic carcinoma is a rare but aggressive type of salivary gland malignancy. This article addresses the need for more effective, biomarker‐informed therapies in rare cancers, focusing on clinical utility and financial sustainability of integrated next‐generation sequencing in routine practice.

Background.

Adenoid cystic carcinoma (ACC) is an aggressive salivary gland malignancy without effective systemic therapies. Delineation of molecular profiles in ACC has led to an increased number of biomarker‐stratified clinical trials; however, the clinical utility and U.S.‐centric financial sustainability of integrated next‐generation sequencing (NGS) in routine practice has, to our knowledge, not been assessed.

Materials and Methods.

In our practice, NGS genotyping was implemented at the discretion of the primary clinician. We combined NGS‐based mutation and fusion detection, with MYB break‐apart fluorescent in situ hybridization (FISH) and MYB immunohistochemistry. Utility was defined as the fraction of patients with tumors harboring alterations that are potentially amenable to targeted therapies. Financial sustainability was assessed using the fraction of global reimbursement.

Results.

Among 181 consecutive ACC cases (2011–2018), prospective genotyping was performed in 11% (n = 20/181; n = 8 nonresectable). Testing identified 5/20 (25%) NOTCH1 aberrations, 6/20 (30%) MYB‐NFIB fusions (all confirmed by FISH), and 2/20 (10%) MYBL1‐NFIB fusions. Overall, these three alterations (MYB/MYBL1/NOTCH1) made up 65% of patients, and this subset had a more aggressive course with significantly shorter progression‐free survival. In 75% (n = 6/8) of nonresectable patients, we detected potentially actionable alterations. Financial analysis of the global charges, including NGS codes, indicated 63% reimbursement, which is in line with national (U.S.‐based) and international levels of reimbursement.

Conclusion.

Prospective routine clinical genotyping in ACC can identify clinically relevant subsets of patients and is approaching financial sustainability. Demonstrating clinical utility and financial sustainability in an orphan disease (ACC) requires a multiyear and multidimensional program.

Implications for Practice.

Delineation of molecular profiles in adenoid cystic carcinoma (ACC) has been accomplished in the research setting; however, the ability to identify relevant patient subsets in clinical practice has not been assessed. This work presents an approach to perform integrated molecular genotyping of patients with ACC with nonresectable, recurrent, or systemic disease. It was determined that 75% of nonresectable patients harbor potentially actionable alterations and that 63% of charges are reimbursed. This report outlines that orphan diseases such as ACC require a multiyear, multidimensional program to demonstrate utility in clinical practice.

Clinical Utility of Rapid EGFR Genotyping in Advanced Lung Cancer

PURPOSE

Targeted therapy is the cornerstone of treatment of advanced EGFR-mutant non-small-cell lung cancer (NSCLC). Next-generation sequencing (NGS), the preferred method for genotyping, typically requires several weeks. Here, we assessed workflows designed to rapidly identify patients with actionable EGFR mutations and reduce time to initiation (TTI) of epidermal growth factor receptor (EGFR)-directed therapy.

PATIENTS AND METHODS

We performed rapid testing for EGFR L858R mutations and exon 19 deletions on paraffin-embedded or frozen section biopsy specimens from newly diagnosed patients with metastatic NSCLC by using an EGFR-specific assay (rapid test). To determine clinical utility, we assessed concordance with NGS results, turnaround time, and TTI of EGFR therapy, and we evaluated reimbursement data.

RESULTS

Between January 2015 and September 2017, we performed 243 rapid EGFR tests and identified EGFR mutations in 43 patients (18%). With NGS results as a reference, sensitivity and specificity of the rapid EGFR polymerase chain reaction assay were 98% and 100%, respectively. The median turnaround time for NGS was 14 days, compared with 7 days for rapid testing (P < .001). In the rapid group, 95% of patients received an EGFR inhibitor in the first-line setting. The median TTI of EGFR therapy was significantly shorter in the rapid cohort when compared with 121 historical cases (22 v 37 days; P = .01). Escalation of the initiative into an interdisciplinary ultra-rapid next-day frozen-section workflow for highly symptomatic patients (n = 8) resulted in a reduction in the median (± standard deviation) turnaround time to 1 ± 0.4 days and allowed several patients to initiate therapy within 1 week of biopsy. An extended 9-month clinical evaluation phase confirmed operational sustainability (turnaround times: ultra-rapid, 0.81 ± 0.4 days; rapid, 3 ± 1.5 days), and a 63% reimbursement rate indicated financial sustainability.

CONCLUSION

Rapid genotyping facilitates earlier initiation of EGFR-directed therapies without compromising NGS workflows.

Parenteral Soybean Oil Induces Hepatosteatosis Despite Addition of Fish Oil in a Mouse Model of Intestinal Failure-Associated Liver Disease

BACKGROUND

Replacement of parenteral soybean oil (SO) with fish oil (FO) is an effective therapy for intestinal failure-associated liver disease (IFALD) in children. However, practitioners remain concerned about the risk of essential fatty acid deficiency (EFAD) and sometimes treat IFALD with a combination of 50% SO and 50% FO emulsions. The purpose of this study was to determine if mixing 50% SO and 50% FO emulsions would prevent hepatosteatosis in a murine model of parenteral nutrition (PN)-induced hepatosteatosis.

METHODS

C57BL/6 mice were randomized to receive oral PN with parenteral saline, FO, SO, or a mixture of 50% FO and 50% SO for 19 days. Fatty acid analysis, histologic evaluation, Nonalcoholic Steatohepatitis Clinical Research Network (NSCRN) scores, and reverse-transcriptase polymerase chain reaction for key lipogenic genes were performed.

RESULTS

The PN + saline group was the only group with EFAD, with a serum and hepatic triene/tetraene ratio of 0.53. NSCRN scores were highest in the PN + SO group (5.5; 95% confidence interval [CI], 4.9-6.1), followed by the PN + FO/SO (4.5; 95% CI, 3.5-5.5) group, with the lowest score in the PN + FO (2.0; 95% CI, 1.1-2.9) group. Acetyl CoA carboxylase α and acetyl CoA carboxylase β expression was lower in the PN + FO group than in the PN + FO/SO or PN + SO groups.

CONCLUSIONS

Our data demonstrate that a mixed fat emulsion of 50% SO and 50% FO is inferior to 100% FO in reducing hepatosteatosis in this model. These data suggest that use of parenteral SO with parenteral FO, in a 1:1 ratio, may still contribute to liver injury, although it is less hepatotoxic than pure SO.

RNA chromogenic in situ hybridization assay with clinical automated platform is a sensitive method in detecting high-risk human papillomavirus in squamous cell carcinoma

Detection of active human papillomavirus (HPV) is clinically important because its presence has been shown to correlate with favorable clinical outcomes and better response to treatment in oropharyngeal squamous cell carcinomas. Using a clinical automated platform, we compared the performance of commercially available HPV DNA and RNA in situ hybridization (ISH) probes in archival tissues of 57 squamous cell carcinomas. Importantly, a clinical automated platform gives (1) consistent and reproducible results for HPV ISH and (2) better standardization across clinical laboratories. Compared with polymerase chain reaction results, RNA ISH exhibited 93% concordance versus 81% of DNA ISH. RNA ISH was more sensitive than DNA ISH (100% versus 88%) and more specific (87% versus 74%). When only accounting for 2+-3+ positivity, sensitivity was 92% for RNA ISH versus 73% for DNA ISH, highlighting the ease of interpretation. p16 exhibited 96% sensitivity, whereas specificity was only 55%. In 3 cases, both RNA and DNA ISH were positive, whereas polymerase chain reaction results were negative, suggesting that ISH methods might be a more sensitive method. Performing on a clinical automated platform, RNA ISH is sensitive in determining high-risk HPV status in formalin-fixed, paraffin-embedded tissues and has the potential of being a standalone clinical test.

A Comparison of Fish Oil Sources for Parenteral Lipid Emulsions in a Murine Model

BACKGROUND

Fat emulsions are important components of parenteral nutrition (PN). Fish oil (FO) emulsions reverse cholestasis in PN-associated liver disease. There are 2 FO monographs. One is "FO; rich in omega-3 fatty acids" (NFO). The other, "omega-3 acids," (PFO), is enriched in omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The purpose of this study is to compare the effects of 20% NFO and PFO emulsions produced in the laboratory in a murine model.

METHODS

Emulsions were compounded containing different oils: soybean oil (SO), NFO, and two PFOs differing in percentage of fatty acids as triglycerides (PFO66 and PFO90). Chow-fed mice received saline, one of the above emulsions, or a commercial FO (OM) intravenously (2.4 g/kg/day) for 19 days. On day 19, animals were euthanized. Livers, spleens, and lungs were procured for histologic analysis.

RESULTS

OM, SO, NFO, and PFO90 were well-tolerated clinically. PFO66 resulted in tachypnea and lethargy for ~1 minute following injections. At euthanasia, PFO66 and PFO90 groups had organomegaly. Histologically, these groups had splenic and hepatic fat-laden macrophages, and lungs had scattered fat deposits. Other groups had normal organs.

CONCLUSIONS

PFO emulsions present an attractive possibility for improving inflammation in PN-dependent patients by concentrating anti-inflammatory EPA and DHA. However, 20% PFO emulsions were poorly tolerated and precipitated adverse end organ sequelae, suggesting that they may not be safe. Development of novel manufacturing methods may achieve safe 20% PFO parenteral emulsions, but by established formulation methods, these emulsions were clinically suboptimal despite meeting pharmacopeial standards.

Eucaloric Ketogenic Diet Reduces Hypoglycemia and Inflammation in Mice with Endotoxemia

Dietary strategies to alter the immune response to acute inflammation have the potential to improve outcomes in critically ill patients. A eucaloric ketogenic diet (EKD), composed predominantly of fat with very small amounts of carbohydrate, can provide adequate caloric support while minimizing spikes in blood glucose and reducing oxidative stress. The purpose of this study was to evaluate the effects of an EKD on glycemic control and the inflammatory response after acute endotoxemia in mice. Mice received either an EKD or a carbohydrate-based control diet (CD) for 4 weeks. Animals subsequently underwent either a 2-h fast (postprandial) or an overnight fast (postabsorptive), and half of the animals in each diet group were randomized to receive either intraperitoneal lipopolysaccharide (1 mg/kg) or an equivalent volume of saline. Glycemic response, insulin resistance, inflammatory cytokine levels, and the expression of key inflammatory and metabolic genes were measured. After endotoxin challenge, hypoglycemia was more frequent in mice fed a CD than an EKD in the postprandial period. This was due in part to the preservation of hepatic glycogen stores despite endotoxin exposure and prolonged fasting in mice fed an EKD. Furthermore, mice fed the CD had higher levels of IL-6 and TNF-α in the postabsorptive period, with a fivefold higher expression of hepatic NFκB compared to mice fed the EKD in both fasting periods. These results suggest that the unique metabolic state induced by an EKD can alter the response to acute inflammation in mice.

MYC Analysis by Fluorescent In Situ Hybridization and Immunohistochemistry in Primary Adrenal Angiosarcoma (PAA): a Series of Four Cases

Primary adrenal angiosarcomas (PAA) are rare with 36 cases reported in the English literature. MYC protein expression and gene amplification have been detected in secondary angiosarcoma (AS), and a subset of primary AS. The aim of this study was to report the clinicopathologic features of PAA and examine these tumors for MYC amplification and protein expression in a small series of four cases (resection, n = 4). Three had available material for ancillary studies and were investigated for MYC gene abnormalities and protein expression using fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Tumors occurred in three females and one male with a mean age of 69 (53-75) years. The sizes ranged from 8.5 to 15 (mean 11.5) cm and were epithelioid in morphology. All tumors had prominent necrosis, and the mitotic count ranged from 4 to 41/10 high-power fields (HPFs) (mean 20/10 HPFs, ×400). Immunohistochemically, the tumor cells were positive for CD31 in 4/4 cases, CD34 in 1/4 cases, and cytokeratin in 4/4 cases. The mean follow-up period was 10.8 (3-19) months, of which three patients died of disease with distant metastases, and one patient was alive with disease. MYC nuclear staining was identified in the three cases tested. Two cases showed polysomy of chromosome 8 without MYC amplification or rearrangement. Two MYC-positive cases by IHC demonstrated copy number gain in chromosome 8, and one MYC-positive case was not associated with a chromosome 8/MYC gene abnormality. In the context of new targeted therapies, MYC positivity in PAA may be clinically valuable in treating patients with these aggressive neoplasms.

Loss of BAP1 Expression in Basal Cell Carcinomas in Patients With Germline BAP1 Mutations

OBJECTIVES

Patients with heterozygous germline mutations in BRCA1-associated protein 1 (BAP1), a tumor suppressor gene, develop a tumor predisposition syndrome (OMIM 614327) with increased risk of uveal and cutaneous melanomas, cutaneous atypical and epithelioid melanocytic lesions, lung adenocarcinoma, clear cell renal cell carcinoma, and other tumors. Early recognition of this syndrome is of clinical importance. In addition, screening for BAP1 mutation, loss, and inactivation by performing BAP1 immunohistochemistry on cutaneous lesions would be a simple method for screening patients suspected of having germline BAP1 mutations.

METHODS

We investigated BAP1 expression in seven basal cell carcinomas (BCCs) in two patients with germline BAP1 mutation and a family history of uveal melanoma. Six lesions were from the head and neck region and one from the shoulder. Thirty-one sporadic BCCs were included as controls.

RESULTS

All seven BCCs in the patients with germline BAP1 mutations exhibited loss of BAP1 nuclear staining, while 30 (97%) of 31 sporadic BCCs exhibited positive BAP1 nuclear staining.

CONCLUSIONS

Loss of BAP1 expression could be associated with the development of BCC in patients with germline BAP1 mutations. These results suggest that BCC may be a component of the expanding category of tumors associated with this syndrome.

The addition of medium-chain triglycerides to a purified fish oil-based diet alters inflammatory profiles in mice

OBJECTIVE

Parenteral nutrition associated liver disease (PNALD) is a deadly complication of long term parenteral nutrition (PN) use in infants. Fish oil-based lipid emulsion has been shown in recent years to effectively treat PNALD. Alternative fat sources free of essential fatty acids have recently been investigated for health benefits related to decreased inflammatory response. We hypothesized that the addition of medium-chain triglycerides (MCT) to a purified fish oil-based diet would decrease the response to inflammatory challenge in mice, while allowing for sufficient growth and development.

MATERIALS/METHODS

Six groups of ten adult male C57/Bl6 mice were pair-fed different dietary treatments for a period of twelve weeks, varying only in fat source (percent calories by weight): 10.84% soybean oil (SOY), 10% coconut oil (HCO), 10% medium-chain triglycerides (MCT), 3% purified fish oil (PFO), 3% purified fish oil with 3% medium-chain triglycerides (50:50 MCT:PFO) and 3% purified fish oil with 7.59% medium-chain triglycerides (70:30 MCT:PFO). An endotoxin challenge was administered to half of the animals in each group at the completion of dietary treatment.

RESULTS

All groups demonstrated normal growth throughout the study period. Groups fed MCT and HCO diets demonstrated biochemical essential fatty acid deficiency and decreased IL-6 and TNF-α response to endotoxin challenge. Groups containing PFO had increased inflammatory response to endotoxin challenge, and the addition of MCT to PFO mitigated this inflammatory response.

CONCLUSION

These results suggest that the addition of MCT to PFO formulations may decrease the host response to inflammatory challenge, which may pose potential for optimized PN formulations. Inclusion of MCT in lipid emulsions given with PN formulations may be of use in therapeutic interventions for disease states resulting from chronic inflammation.

Repurposing the FDA-approved pinworm drug pyrvinium as a novel chemotherapeutic agent for intestinal polyposis

Mutations in the WNT-pathway regulator ADENOMATOUS POLYPOSIS COLI (APC) promote aberrant activation of the WNT pathway that is responsible for APC-associated diseases such as Familial Adenomatous Polyposis (FAP) and 85% of spontaneous colorectal cancers (CRC). FAP is characterized by multiple intestinal adenomas, which inexorably result in CRC. Surprisingly, given their common occurrence, there are few effective chemotherapeutic drugs for FAP. Here we show that the FDA-approved, anti-helminthic drug Pyrvinium attenuates the growth of WNT-dependent CRC cells and does so via activation of CK1α. Furthermore, we show that Pyrvinium can function as an in vivo inhibitor of WNT-signaling and polyposis in a mouse model of FAP: APC^min mice. Oral administration of Pyrvinium, a CK1α agonist, attenuated the levels of WNT-driven biomarkers and inhibited adenoma formation in APC^min mice. Considering its well-documented safe use for treating enterobiasis in humans, our findings suggest that Pyrvinium could be repurposed for the clinical treatment of APC-associated polyposes.

VE1 antibody immunoreactivity in normal anterior pituitary and adrenal cortex without detectable BRAF V600E mutations

OBJECTIVES

The VE1 monoclonal antibody was developed to recognize the V600E mutation in BRAF, which is found in various tumors.

METHODS

We report that the VE1 antibody stains normal anterior pituitary gland and adrenal cortex, which lack detectable BRAF V600E mutations.

RESULTS

Staining with the VE1 antibody was seen in the adenohypophysis and correlated well with adrenocorticotropic hormone (ACTH)-positive cells. ACTH-positive cells were typically most concentrated in the central mucoid wedge and pars intermedia, and VE1 staining was strong in these regions. Moreover, VE1 staining was seen in ACTH-expressing pituitary adenomas without detectable BRAF mutations. VE1 staining of the adrenal cortex was also significant, with the strongest staining seen in the inner segment of the zona fasciculata. Parathyroid glands, pancreatic islets, or parafollicular C cells in the thyroid showed no VE1 staining.

CONCLUSIONS

Overall, VE1 staining of endocrine tissues strongly suggests limitations on the use of this antibody for the detection of BRAF mutations.

The effect of docosahexaenoic acid on bone microstructure in young mice and bone fracture in neonates

BACKGROUND

As low bone mineral density is a risk factor for fracture in childhood, optimizing age appropriate bone mass is recommended and might lower the impact of bone loss related to age. Consumption of omega-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic and docosahexaenoic (DHA) acids have been shown to beneficially modulate bone metabolism. The objective of this study was to determine the incidence of fracture in neonates receiving a fish compared with soybean oil-based intravenous lipid emulsion and evaluate the effect of varying dietary omega-3 PUFA consumption on growing bone in young mice.

MATERIALS AND METHODS

Eligibility criteria for the clinical study included gestational age ≤37 wk and parenteral nutrition-dependence for ≥4 wk. Radiographs were reviewed after lipid initiation to identify radiologic bone fracture. The animal study evaluated female C57/Bl6 mice randomized into one of five groups from age 3-12 wk, at which time femurs were harvested for micro-computed tomography and light microscopy analysis.

RESULTS

A lower incidence of bone fracture was found in neonates maintained on fish compared with soybean oil. In the animal study, findings suggest the DHA diet provides the best protection against trabecular bone loss as evidenced by increased bone volume fraction, increased trabecular number, and decreased trabecular separation on micro-computed tomography. These protective effects appeared to affect the bone microstructure alone.

CONCLUSIONS

The lower fracture risk observed in fish oil fed neonates in combination with the protective effects of DHA observed in the femurs of young C57/BL6 mice suggest an important role for omega-3 PUFAs on bone growth.

The effect of varying ratios of docosahexaenoic acid and arachidonic acid in the prevention and reversal of biochemical essential fatty acid deficiency in a murine model

OBJECTIVE

Essential fatty acids (EFA) are necessary for growth, development, and biological function, and must be acquired through the diet. While linoleic acid (LA) and alpha-linolenic acid (ALA) have been considered the true EFAs, we previously demonstrated that docosahexaenoic acid (DHA) and arachidonic acid (AA) taken together as the sole source of dietary fatty acids can prevent biochemical essential fatty acid deficiency (EFAD). This study evaluates the effect of varying dietary ratios of DHA:AA in the prevention and reversal of biochemical EFAD in a murine model.

METHODS

Using a murine model of EFAD, we provided mice with 2.1% of daily caloric intake in varying DHA:AA ratios (1:1, 5:1, 10:1, 20:1, 200:1, 100:0) for 19 days in association with a liquid high-carbohydrate fat-free diet to evaluate the effect on fatty acid profiles. In a second experiment, we evaluated the provision of varying DHA:AA ratios (20:1, 200:1, 100:0) on the reversal of biochemical EFAD.

RESULTS

Mice provided with DHA and AA had no evidence of biochemical EFAD, regardless of the ratio (1:1, 5:1, 10:1, 20:1, 200:1, 100:0) administered. Biochemical EFAD was reversed with DHA:AA ratios of 20:1, 200:1, and 100:0 following 3 and 5 weeks of dietary provision, although the 20:1 ratio was most effective in the reversal and stabilization of the triene:tetraene ratio.

CONCLUSION

Provision of DHA and AA, at 2.1% of daily caloric intake in varying ratios can prevent biochemical evidence of EFAD and hepatic steatosis over the short-term, with a ratio of 20:1 DHA:AA most effectively reversing EFAD.

SCF(β-TRCP) suppresses angiogenesis and thyroid cancer cell migration by promoting ubiquitination and destruction of VEGF receptor 2

The E3 ubiquitin ligase β-TRCP, acting in concert with casein kinase I, drives ubiquitination and degradation of VEGFR2, and renders human papillary thyroid cancer cells resistant to the VEGFR2 inhibitor sorafenib.

The incidence of human papillary thyroid cancer (PTC) is increasing and an aggressive subtype of this disease is resistant to treatment with vascular endothelial growth factor receptor 2 (VEGFR2) inhibitor. VEGFR2 promotes angiogenesis by triggering endothelial cell proliferation and migration. However, the molecular mechanisms governing VEGFR2 stability in vivo remain unknown. Additionally, whether VEGFR2 influences PTC cell migration is not clear. We show that the ubiquitin E3 ligase SCF^β-TRCP promotes ubiquitination and destruction of VEGFR2 in a casein kinase I (CKI)–dependent manner. β-TRCP knockdown or CKI inhibition causes accumulation of VEGFR2, resulting in increased activity of signaling pathways downstream of VEGFR2. β-TRCP–depleted endothelial cells exhibit enhanced migration and angiogenesis in vitro. Furthermore, β-TRCP knockdown increased angiogenesis and vessel branching in zebrafish. Importantly, we found an inverse correlation between β-TRCP protein levels and angiogenesis in PTC. We also show that β-TRCP inhibits cell migration and decreases sensitivity to the VEGFR2 inhibitor sorafenib in poorly differentiated PTC cells. These results provide a new biomarker that may aid a rational use of tyrosine kinase inhibitors to treat refractory PTC.

Docosahexaenoic acid and arachidonic acid prevent essential fatty acid deficiency and hepatic steatosis

OBJECTIVES

Essential fatty acids are important for growth, development, and physiologic function. α-Linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, the authors hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids.

METHODS

Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, the authors provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis.

RESULTS

Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks.

CONCLUSION

Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without α-linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model.

Atypical pituitary adenomas: incidence, clinical characteristics, and implications

Object

The 2004 WHO classification of pituitary adenomas now includes an “atypical” variant, defined as follows: MIB-1 proliferative index greater than 3%, excessive p53 immunoreactivity, and increased mitotic activity. The authors review the incidence of this atypical histopathological subtype and its correlation with tumor subtype, invasion, and surgical features.

Methods

The records of 121 consecutive patients who underwent transsphenoidal surgery for pituitary adenomas during an 18-month period were retrospectively reviewed for evidence of atypical adenomas.

Results

Eighteen adenomas (15%) met the criteria for atypical lesions; 17 (94%) of the 18 were macroadenomas. On imaging, 15 (83%) demonstrated imaging evidence of surrounding invasion, compared with 45% of typical adenomas (p = 0.004). Atypical tumors occurred in 12 female (67%) and 6 male (33%) patients. Patient age ranged from 16 to 70 years (mean 48 years). Nine patients (50%) had hormonally active tumors, and 9 had nonfunctional lesions. Four (22%) of the 18 patients presented to us with recurrent tumors. Immunohistochemical analysis demonstrated the following tumor subtypes: GH-secreting adenoma with plurihormonal staining (5 patients [28%]); null-cell adenoma (5 patients [28%]); silent ACTH tumor (3 patients [17%]), ACTH-staining tumor with Cushing's disease (2 patients [11%]), prolactinoma (2 patients [11%]), and silent FSH-staining tumor (1 patient [6%]). The MIB-1 labeling index ranged from 3% to 20% (mean 7%).

Conclusions

Atypical tumors were identified in 15% of resected pituitary adenomas, and they tended to be aggressive, invasive macroadenomas. More longitudinal follow-up is required to determine whether surgical outcomes, potential for recurrence, or metastasis of atypical adenomas vary significantly from their typical counterparts.

Thyroid nodules and cancer in children with PTEN hamartoma tumor syndrome

CONTEXT

Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a complex disorder caused by germline-inactivating mutations of the PTEN tumor suppressor gene. Carriers develop benign and malignant tumors of multiple tissues, including the breast, thyroid, intestine, and skin. Surveillance to facilitate the early detection and treatment of malignancies is recommended but, because thyroid cancers have been reported almost exclusively in adults, childhood risk is considered to be low, and consensus guidelines recommend that surveillance imaging begin at 18 yr of age.

OBJECTIVE/PATIENTS

Seven children with PHTS referred to two thyroidologists form the basis of this report. Medical records, operative histology, and PTEN mutational analysis were reviewed to evaluate the pediatric presentation of PHTS-associated thyroid neoplasia.

RESULTS

Five of the seven children presented with thyroid nodules or thyroid cancer between the ages of 6 and 12 yr, often as the initially identified component of their PHTS. Two others were diagnosed with PHTS on the basis of extrathyroidal features but had markedly abnormal screening ultrasounds with solid thyroid nodule(s) of at least 2 cm, despite the documentation of normal physical examinations. Five of the seven children in this cohort developed thyroid cancer.

CONCLUSIONS

Patients with PHTS can develop thyroid nodules and thyroid cancer in early childhood. This argues both for a high index of suspicion for PHTS in children diagnosed with multiple thyroid nodules and for careful thyroid surveillance in children diagnosed with PHTS. Because early detection improves the outcome of thyroid cancer, we recommend ultrasound surveillance for all patients upon the confirmation of a germline PTEN mutation, regardless of their age.

Effects of metalloproteinase inhibition in a murine model of renal ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a leading cause of acute tubular necrosis (ATN) and delayed graft function in transplanted organs. Up-regulation of matrix metalloproteinases (MMPs) propagates the microinflammatory response that drives IRI. This study sought to determine the specific effects of Marimastat (Vernalis, BB-2516), a broad spectrum MMP and TNF-alpha-converting enzyme inhibitor, on IRI-induced ATN. Mice were pretreated with Marimastat or methylcellulose vehicle for 4 d before surgery. Renal pedicles were bilaterally occluded for 30 min and allowed to reperfuse for 24 h. Baseline creatinine levels were consistent between experimental groups; however, post-IRI creatinine levels were 4-fold higher in control mice (p < 0.0001). The mean difference between the post-IRI histology grades of Marimastat-treated and control kidneys was 1.57 (p = 0.003), demonstrating more severe damage to control kidneys. Post-IRI mean (+/-SEM) MMP-2 activity rose from baseline levels in control mice (3.62 +/- 0.99); however, pretreated mice presented only a slight increase in mean MMP-2 activity (1.57 +/- 0.72) (p < 0.001). In conclusion, these data demonstrate that MMP inhibition is associated with a reduction of IRI in a murine model.

Reduction of hepatocellular injury after common bile duct ligation using omega-3 fatty acids

PURPOSE

Bile duct obstruction and subsequent cholestasis produces hepatocellular injury and an inflammatory response. Fatty acid constitution of cell membranes plays a major role in the inflammatory cascade. Omega-3 fatty acids are antiinflammatory. We proposed that omega-3 fatty acid supplementation would reduce hepatocellular damage and cell death in a model of murine common bile duct ligation.

METHODS

Mice underwent bile duct ligation and were administered either control soy diet (omega-6) or Menhaden diet (omega-3), and parameters of liver injury were measured at postoperative days 1, 4, and 8. Serum was analyzed for liver function tests. Liver tissue was scored for histologic necrosis and inflammation, and apoptosis was qualitatively measured.

RESULTS

At day 8, comparing control and Menhaden, liver function tests were not significantly different. The H&E slides were analyzed and scored. At day 4, the mean necrosis scores for the Menhaden-fed group was 0.01 +/- 0.028 and 0.46 +/- 0.108 for the soy-fed group (P = .001) and at day 8, 0.420 +/- 0.107 and 1.22 +/- 0.132 (P < .001). The mean portal inflammation score for day 4 Menhaden-fed and soy-fed mice was 1.40 +/- 0.245 for both groups (P = 1.00) and for day 8, 1.80 +/- 0.200 and 2.80 +/- 0.200 (P = .008). At day 1, the median terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling scores of the Menhaden vs soy group were 6.0 and 0.0 (P < .001); day 4, 24.0 and 3.0 (P < .001); and day 8, 0.0 and 3.0 (P < .001), respectively.

CONCLUSION

Although there appears to be a trend toward biochemical protection and a marked reduction of necrosis and inflammation, there was no significant liver function test difference between control and Menhaden groups. Considering our data of blunted histologic hepatotoxicity with omega-3 fatty acid supplementation, we hypothesize that this may be a method of reducing long-term complications of liver injury secondary to diseases of cholestasis such as biliary atresia, namely fibrosis and cirrhosis.

Multiple endocrine neoplasia type 1-associated thyrotropin-producing pituitary carcinoma: report of a probable de novo example

Pituitary carcinomas are exceedingly rare. At present, the sole diagnostic criterion is metastatic spread, either craniospinal or systemic. There is no agreement on a histologic, immunohistochemical, and/or ultrastructural definition. We report a clinically and morphologically well-documented example of pituitary thyrotropin cell carcinoma in a man with multiple endocrine neoplasia type 1 syndrome. The tumor produced thyrotropin, alpha-subunit, and prolactin and, through electron microscopy, was found to consist solely of Thyrotroph cells. Over a protracted course, craniospinal and systemic metastases were noted. The primary and metastatic deposits of this aggressive tumor were studied. To our knowledge, this tumor is the first reported case of thyrotropin cell carcinoma occurring in association with the multiple endocrine neoplasia type 1 syndrome. The literature regarding thyrotropin carcinomas is reviewed. Based on the study of several biopsies during disease progression, we believe that the carcinoma originated de novo without an intermediary adenoma phase.

Vascular endothelial growth factor accelerates compensatory lung growth after unilateral pneumonectomy

We hypothesize that compensatory lung growth after unilateral pneumonectomy in a murine model is, in part, angiogenesis dependent and can be altered using angiogenic agents, possibly through regulation of endothelial cell proliferation and apoptosis. Left pneumonectomy was performed in mice. Mice were then treated with proangiogenic factors [vascular endothelial growth factor (VEGF); basic fibroblast growth factor (bFGF)], VEGF receptor antibodies (MF-1, DC101), and VEGF receptor small molecule chemical inhibitors. Lung volume and mass were measured. The lungs were analyzed using immunohistochemistry by CD31 staining, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling, type II pneumocytes staining, and proliferating cell nuclear antigen. Compensatory lung growth was complete by postoperative day 10 and was associated with diffuse apoptosis of endothelial cells and pneumocytes. This process was accelerated by VEGF, such that growth was complete by postoperative day 4 with similar associated apoptosis. bFGF had no effect on lung growth. MF-1 and DC101 had no effect. The VEGF receptor small molecule chemical inhibitors also had no effect. VEGF, but not bFGF, accelerates growth. VEGF receptor inhibitors do not block growth, suggesting that other proangiogenic factors play a role or can compensate for VEGF receptor blockade. Diffuse apoptosis, endothelial cell and pneumocyte, occurs at cessation of both normal compensatory and VEGF-accelerated growth. Angiogenesis modulators may control growth via regulation of endothelial cell proliferation and apoptosis, although the exact relationship between endothelial cells and pneumocytes has yet to be determined. The fact that bFGF did not accelerate growth in our model when it did accelerate regeneration in the liver model suggests that angiogenesis during organ regeneration is regulated in an organ-specific manner.

Inhibition of matrix metalloproteinases increases PPAR-alpha and IL-6 and prevents dietary-induced hepatic steatosis and injury in a murine model

Steatosis is a prominent feature of nonalcoholic fatty liver disease and a potential promoter of inflammation. Injury leading to cirrhosis is partly mediated by dysregulation of matrix protein turnover. Matrix metalloproteinase (MMP) inhibitors protect mice from lethal TNF-alpha induced liver injury. We hypothesized that Marimastat, a broad-spectrum MMP and TNF-alpha converting enzyme (TACE) inhibitor, might modulate this injury through interruption of inflammatory pathways. Triglyceride and phospholipid levels (liver, serum) and fatty acid profiles were used to assess essential fatty acid status and de novo lipogenesis as mechanisms for hepatic steatosis. Mice receiving a fat-free, high-carbohydrate diet (HCD) for 19 days developed severe fatty liver infiltration, demonstrated by histology, magnetic resonance spectroscopy, and elevated liver function tests. Animals receiving HCD plus Marimastat (HCD+MAR) were comparable to control animals. Increased tissue levels of peroxisome proliferator activated receptor-alpha (PPAR-alpha), higher levels of serum IL-6, and decreased levels of serum TNF-alpha receptor II were also seen in the HCD+MAR group compared with HCD-only. In addition, there was increased phosphorylation, and likely activation, of PPAR-alpha in the HCD+MAR group. PPAR-alpha is a transcription factor involved in beta-oxidation of fatty acids, and IL-6 is a hepatoprotective cytokine. Liver triglyceride levels were higher and serum triglyceride and phospholipid levels lower with HCD-only but improved with Marimastat treatment. HCD-only and HCD+MAR groups were essential fatty acid deficient and had elevated rates of de novo lipogenesis. We therefore conclude that Marimastat reduces liver triglyceride accumulation by increasing fat oxidation and/or liver clearance of triglycerides. This may be related to increased expression and activation of PPAR-alpha or IL-6, respectively.

Severe hypoglycaemia post-gastric bypass requiring partial pancreatectomy: evidence for inappropriate insulin secretion and pancreatic islet hyperplasia

AIMS/HYPOTHESIS

Postprandial hypoglycaemia following gastric bypass for obesity is considered a late manifestation of the dumping syndrome and can usually be managed with dietary modification. We investigated three patients with severe postprandial hypoglycaemia and hyperinsulinaemia unresponsive to diet, octreotide and diazoxide with the aim of elucidating the pathological mechanisms involved.

METHODS

Glucose, insulin, and C-peptide were measured in the fasting and postprandial state, and insulin secretion was assessed following selective intra-arterial calcium injection. Pancreas histopathology was assessed in all three patients.

RESULTS

All three patients had evidence of severe postprandial hyperinsulinaemia and hypoglycaemia. In one patient, reversal of gastric bypass was ineffective in reversing hypoglycaemia. All three patients ultimately required partial pancreatectomy for control of neuroglycopenia; pancreas pathology of all patients revealed diffuse islet hyperplasia and expansion of beta cell mass.

CONCLUSIONS/INTERPRETATION

These findings suggest that gastric bypass-induced weight loss may unmask an underlying beta cell defect or contribute to pathological islet hyperplasia, perhaps via glucagon-like peptide 1-mediated pathways.

The route of lipid administration affects parenteral nutrition-induced hepatic steatosis in a mouse model

BACKGROUND

The etiology of parenteral nutrition (PN)-associated hepatic injury remains unresolved. Recent studies have suggested that the intravenous (IV) lipid emulsion administered with PN may contribute to PN-associated hepatic injury. We therefore examined whether the route of lipid administration would affect the development of PN-associated liver injury in a previously established animal model of PN-induced hepatic steatosis.

METHODS

Mice were fed ad libitum PN solution as their only nutritional source for 19 days with lipid supplementation by either the enteral or the IV route. Control mice received chow alone, and a final group received enteral PN solution without lipid supplementation.

RESULTS

All mice gained equivalent weight during the study. Mice receiving PN alone or PN with IV lipid developed severe histologic liver damage that was not seen in control mice or in mice receiving PN with enteral lipid. Liver fat content as measured by magnetic resonance spectroscopy was significantly lower in the control and enteral lipid groups when compared with mice receiving PN alone or with IV lipid. Mice receiving enteral lipid had significantly lower levels of serum aspartate aminotransferase and alanine aminotransferase compared with animals receiving PN alone.

CONCLUSIONS

These data provide preliminary evidence that lipid administered through the enteral route protects against PN-associated hepatic injury in an animal model.

Prevention of intra-abdominal adhesions using the antiangiogenic COX-2 inhibitor celecoxib

OBJECTIVE

To determine the effects of COX-2 specific inhibitors on postoperative adhesion formation.

SUMMARY AND BACKGROUND DATA

Intra-abdominal adhesions are the major cause of intestinal obstruction and secondary infertility after surgical procedures. Because adhesion synthesis requires angiogenesis, and cyclooxygenase-2 enzyme (COX-2) inhibitors have antiendothelial activity, we tested COX-2 inhibitors in a murine model of intra-abdominal adhesion formation.

METHODS

A silicone patch was secured to the lateral abdominal wall of groups of C57BL/6 mice, followed by cecal abrasion to promote adhesion formation. Beginning on the day of surgery, mice were treated with the selective COX-2 agents, celecoxib or rofecoxib, and the nonspecific COX inhibitors, aspirin, naproxen, ibuprofen, or indomethacin. Animals were treated for 10 days and killed. A second group (celecoxib, rofecoxib, aspirin) was treated for 10 days and observed for an additional 25 days. After treatment, intra-abdominal adhesions were scored using a standard method. The patch was subjected to immunohistochemistry with the endothelial-specific marker, CD31.

RESULTS

Animals treated with selective and nonselective COX-2 inhibitors, except aspirin, had significantly fewer adhesions than control animals. Celecoxib produced a maximal reduction in adhesion formation compared with rofecoxib and the nonselective COX-2 inhibitors at 10 days. After 25 days, celecoxib and rofecoxib, but not aspirin, had fewer adhesions than control mice. Adhesions from mice treated with celecoxib had reduced microvessel density compared with rofecoxib, the nonselective COX inhibitors, and control animals.

CONCLUSIONS

Selective COX-2 inhibitors, in particular celecoxib, provide durable inhibition of intra-abdominal adhesions through an antiangiogenic mechanism.

Midline Carcinoma of Children and Young Adults With NUT Rearrangement

Purpose

A balanced chromosomal translocation, t(15;19), resulting in the BRD4-NUT oncogene, has been identified in a lethal carcinoma of young people, a disease described primarily in case reports. We sought to amass a more definitive series of tumors with NUT and/or BRD4 gene rearrangements and to determine distinct clinicopathologic features.

Patients and Methods

Carcinomas (N = 98) in young individuals (median age, 32.5 years) were screened for NUT and BRD4 rearrangements using dual-color fluorescence in situ hybridization. Four published carcinomas with BRD4 and NUT rearrangements were also evaluated. Immunophenotypic analyses were performed.

Results

Eleven tumors had NUT gene rearrangements, including eight with BRD4-NUT fusions and three with novel rearrangements, which were designated as NUT variant. All NUT-rearranged carcinomas (NRCs) arose from midline epithelial structures, including the first example arising below the diaphragm. Patients were young (median age, 17.6 years). Squamous differentiation (seen in 82% of NRCs) was particularly striking in NUT-variant cases. In this first description of NUT-variant carcinomas, the average survival (96 weeks, n = 3) was longer than for BRD4-NUT carcinomas (28 weeks, n = 8). Strong CD34 expression was found in six of 11 NRCs but in zero of 45 NUT wild-type carcinomas.

Conclusion

NRCs arise from midline structures in young people, and NRCs with BRD4-NUT are highly lethal, despite intensive therapies. NUT-variant carcinomas might have a less fulminant clinical course than those with BRD4-NUT fusions. CD34 expression is characteristic in NRCs and, therefore, holds promise as a diagnostic test for this distinctive clinicopathologic entity.

Genetic and biological subgroups of low-stage follicular thyroid cancer

Investigations of cancer-specific gene rearrangements have increased our understanding of human neoplasia and led to the use of the rearrangements in pathological diagnosis of blood cell and connective tissue malignancies. Here, we have investigated 3p25 rearrangements of the peroxisome proliferator-activated receptor gamma (PPAR gamma) gene in follicular epithelial tumors of the human thyroid gland. Eleven of 42 (26%) low-stage follicular carcinomas, 0 of 40 follicular adenomas, 1 of 30 Hurthle cell carcinomas, 1 of 90 papillary carcinomas, and 0 of 10 nodular goiters had 3p25 rearrangements by interphase fluorescence in situ hybridization. All 11 follicular carcinomas with 3p25 rearrangement exhibited strong, diffuse nuclear immunoreactivity for PPAR gamma, consistent with expression of PPAR gamma fusion protein. Twelve of 42 (29%) low-stage follicular carcinomas had 3p25 aneusomy without PPAR gamma rearrangement (P = 0.01), suggesting that PPAR gamma rearrangement and aneuploidy are independent early events in follicular cancer. Eleven of 12 follicular carcinomas with 3p25 aneusomy exhibited no PPAR gamma immunoreactivity, supporting the existence of two independent pathways. Follicular carcinoma patients with PPAR gamma rearrangement more frequently had vascular invasion (P = 0.01), areas of solid/nested tumor histology (P < 0.001), and previous non-thyroid cancers (P < 0.01) compared with follicular carcinoma patients without PPAR gamma rearrangement. Our experiments identify genetic subgroups of low-stage follicular thyroid cancer and provide evidence that follicular carcinomas with PPAR gamma rearrangement are a distinct biological entity. The findings support a model in which separate genetic alterations initiate distinct pathways of oncogenesis in thyroid carcinoma subtypes.