Assessment of microsatellite instability in very small microdissected samples and in tumor samples that are contaminated with normal DNA

Microsatellite instability (MSI) testing is important for the management of young patients with colonic adenocarcinoma. Biopsies can be small and can be contaminated by normal cells. It is not known how sample size or contamination by non-neoplastic cell populations affects the interpretation of MSI assays. Serial microdissection targets (0.75 to 5.5 mm) were obtained from cases with high-level MSI. Polymerase chain reaction was performed for the standard National Cancer Institute recommended markers and products were analyzed by capillary electrophoresis. DNA from a patient with a BAT25 polymorphism was used to determine the sensitivity of detecting an aberrant allele in otherwise normal DNA. In small targets, MSI was seen sporadically in the setting of low DNA concentration. The results for small targets ranged from 1/4 to 5/5 loci with MSI, secondary to allelic dropout. In the sensitivity study, the aberrant allele was detected only when present at a concentration of above 10%. Allelic dropout can lead to under-estimation of the presence of MSI in small tissue samples or samples with low DNA concentration. Contaminating normal cell DNA can mask the presence of MSI. MSI testing on tissue fragments that are <5.5 mm can lead to a false-negative MSI test.

Fractional allelic loss of tumor suppressor genes identifies malignancy and predicts clinical outcome in follicular thyroid tumors

Thyroid follicular tumors can be challenging diagnostically and clinically, because the cytologic and histologic features can be subtle and prognosis is also difficult to predict. In this study, we analyzed thyroid follicular tumors with known long-term follow-up for a molecular panel of tumor suppressor genes to determine whether this molecular approach has prognostic significance. Microdissection and DNA extraction were performed from tumor and normal tissue. Polymerase chain reaction (PCR) was performed for 13 short tandem repeats at or near tumor suppressor genes. PCR product was detected using semiquantitative capillary gel electrophoresis and fractional allelic loss (FAL) was calculated. We included eight adenomas, three minimally invasive carcinomas, four angioinvasive carcinomas, and three widely invasive carcinomas with a mean follow-up of 77 months. Three patients died of disease and an additional two are alive with disease recurrence/metastasis. The mean FAL for benign tumors (14%) was significantly different from that of malignant tumors (56%, p < 0.001). Patients with a follicular tumor who had no evidence of disease recurrence had a mean FAL of 22% and those with disease recurrence or death from disease had a mean of 78% (p < 0.002). Based on these results, a tumor suppressor gene panel for allelic imbalance in follicular-derived tumors (FTT) may correlate with both malignancy and outcome in patients with follicular-derived carcinomas of the thyroid.

Repeat thyroid nodule fine-needle aspiration in patients with initial benign cytologic results

Fine-needle aspiration (FNA) is the standard of care for the initial workup of thyroid nodules, but there is no consensus algorithm to manage patients with benign results. We examined performance characteristics of initial and repeat satisfactory FNAs for all 402 patients who underwent thyroid surgery during a recent 22-month period. Of these patients, 267 had at least 1 satisfactory FNA and 70 had 2 or more. After an initial benign FNA, 1 repeat FNA correctly identified an unsuspected malignancy in 2 of 70 patients and was indeterminate in 17; of these, 7 of 17 were identified as malignant in the final pathologic diagnosis. Overall, the use of 1 repeat FNA increased the sensitivity for malignancy from 81.7% to 90.4% and decreased the false-negative rate from 17.1% to 11.4%. With more than 1 repeat FNA, there was no improvement in performance characteristics. These data make a strong argument for 1 repeat FNA following an initial benign FNA diagnosis.

Comparison of allelic losses in chondroblastoma and primary chondrosarcoma of bone and correlation with fluorescence in situ hybridization analysis

Chondroblastoma (CBL) is a benign neoplasm of bone for which the genomic characteristics remain unclear. We compared the status of allelic losses of CBL with that seen in a set of chondrosarcomas (CS) to determine whether differences in their natural history and behavior are also reflected genetically. Eleven cases of CBL and 10 cases of CS of different grades were included. Tumors were subjected to microdissection and polymerase chain reaction using 17 markers located near genes on chromosomes 5, 9, 11, 13, 17, and 19. The selected chromosomes are known to be involved in several mesenchymal neoplasms. Fluorescence in situ hybridization was also performed on tumors displaying allelic losses, with dual-color probes for 9p, 17p, and 13q. Fractional allelic losses per gene ranged from 18.2% to 63.7% in CBLs and from 28.6% to 66.7% in CSs. Loss of heterozygosity (LOH) of 5q, 9p, 11p, 13q, and 19q occurred in both CBLs and CSs. Loss of heterozygosity of 17p (p53 locus) occurred in 7 of 11 CBLs and in only 1 case of recurrent CS. The pattern of allelic loss was similar in low-grade CSs and CBLs. Loci with LOH in both tumor types suggest possible involvement of the genes p53, RB1, CDKN2/p16, ERC, and XRCC in tumorigenesis. Overall correlation between LOH and fluorescence in situ hybridization results was 90% with 17p13, 80% with 9p, and 60% with 13q. The role of p53 in CBL is uncertain; however, given the benign behavior of this tumor, it is probably unrelated to tumor progression.

NM-23 gene loss of heterozygosity and protein expression in high-stage laryngeal squamous cell carcinomas

Tumor suppressor genes that reduce metastatic potential have been described in a variety of different tumor types. One of the main tumor metastasis suppressor genes is nm-23, which is a nucleoside diphosphate kinase. Two isotypes, nm-23H1 and nm-23H2, have been cloned and map to chromosome 17q21.3. In a variety of tumors, including colon cancer and breast cancer, loss of expression of nm-23 is associated with lymph node metastasis. In other organ systems, however, this relationship is not seen. In head and neck squamous cell carcinomas (HNSCC), there have been conflicting results regarding the association between nm-23 protein expression and metastatic potential. To further explore the tumor metastasis suppressor function of nm-23 in HNSCC, we studied high-stage laryngeal carcinomas, tumors with and without cervical lymph node metastasis for nm-23 protein expression and loss of heterozygosity of the gene locus. Twenty-five cases were included (11 cases with and 14 cases without metastasis). Loss of heterozygosity for the nm-23 gene locus was seen in 7 of 22 (32%) informative tumors. Using immunohistochemistry, most tumors expressed nm-23, though decreased expression was seen in 10 of 25 (40%) cases. Only 2 tumors showed negative expression. We did not find a correlation between either protein expression or loss of heterozygosity with metastatic disease or any other adverse prognostic factors in this group of high-stage laryngeal squamous cell carcinomas. These data imply that nm-23 may be tumor suppressor gene involved in HNSCC but that it may not function as a tumor metastasis suppressor in high-stage laryngeal carcinoma.

Malignant mixed tumors of the salivary gland: a study of loss of heterozygosity in tumor suppressor genes

Carcinosarcomas and carcinoma ex pleomorphic adenoma of the salivary glands are rare tumors that fit into the broader category of malignant mixed tumors. Although most evidence has suggested that the different morphologic components arise from a common clonal origin, there are very few studies that have provided molecular evidence for this clonality. In this study, we examined a set of seven carcinosarcomas and four carcinomas ex pleomorphic adenoma for tumor suppressor gene loss of heterozygosity, in order to assess the clonal patterns in the varying components. Microdissection was performed to obtain each morphological component and tumor suppressor gene loci on 3p, 5q, 9p, 17p, 17q, and 18q were analyzed. The fractional allelic loss (FAL) was calculated for each area, and the different targets were compared for their molecular profile. The overall mean FAL of the malignant targets was 42%. In carcinosarcomas, the sarcomatous targets had a higher mean FAL than the carcinomatous targets (68 vs 46%, respectively) and in carcinomas ex pleomorphic adenoma, the mean FAL in the benign component was 11 vs 46% seen in the carcinomatous component. The most frequently lost genetic loci were p53 (17p13, 73%), nm23-H1 (17q21, 55%), and DCC (18q21, 50%). Loss of heterozygosity of 17q21 and 9p21 only occurred in carcinosarcomas and not in carcinomas ex pleomorphic adenoma. Within the carcinosarcomas, the mutational profiles were conserved between epithelial and sarcomatous areas. In carcinomas ex pleomorphic adenoma, loss of heterozygosity was uncommon in the benign component, but the mutations were conserved in the corresponding malignant areas. These results support the hypothesis that the carcinomatous and sarcomatous components of carcinosarcomas are clonally related. Furthermore, these data support prior studies that suggest a common clonal origin for the benign and malignant components of carcinomas ex pleomorphic adenoma.

Nasal chondromesenchymal hamartoma in older children and adults: series and immunohistochemical analysis

CONTEXT

Nasal chondromesenchymal hamartoma is a benign mass lesion of the nasal cavity predominantly described in young infants. These unusual lesions are composed of a proliferation of mesenchymal and cartilaginous elements. Their pathogenesis is unknown, but they may be derived from embryologic rests. To our knowledge, only 1 case in an older child has been reported, and no cases have been reported in adults.

OBJECTIVE

To report 4 cases of nasal chondromesenchymal hamartoma occurring in older children and adults, including immunohistochemical analysis of these unusual lesions.

DESIGN

Cases identified from our archives were examined to confirm the diagnosis of nasal chondromesenchymal hamartoma. Immunohistochemical analysis was performed using a panel of antibodies (epithelial membrane antigen, smooth muscle actin, all muscle actin, cytokeratin, S100, and KP1) to evaluate for epithelial, smooth muscle, neural, chondroid, and histiocytic differentiation.

RESULTS

Four cases of nasal chondromesenchymal hamartoma in patients of 11, 69, 17, and 25 years of age demonstrated histologic evidence of mesenchymal and cartilaginous elements underlying a chronically inflamed respiratory mucosa. Bony and adipose elements and rare glandular elements were interspersed. Cartilaginous elements stained strongly with S100, whereas mesenchymal regions showed variable and weaker staining. Smooth muscle differentiation was seen primarily in the mesenchymal areas. Epithelial membrane antigen was focally positive in all cases.

CONCLUSIONS

Nasal chondromesenchymal hamartomas can rarely occur in the older child and adult. Mesenchymal areas show both myofibroblastic and cartilaginous differentiation. We speculate that inflammation or a recapitulation of developmental signals may be components in the pathogenesis of these lesions.

Analysis of Allelic Loss as an Adjuvant Tool in Evaluation of Malignancy in Uterine Smooth Muscle Tumors

Uterine smooth muscle tumors of uncertain malignant potential (STUMPs) are difficult both from the diagnostic and patient management standpoint because they cannot be classified as benign or malignant by conventional histologic criteria. This study's aim was to determine the diagnostic utility of allelic imbalance (AI) analysis in uterine smooth muscle tumors. Using microdissection and genotyping, we tested 5 leiomyomas, 6 STUMPs, and 10 leiomyosarcomas with follow-up for AI across a panel of seven tumor suppressor genes (p16, p21, p53, VHL, XRCC3, RB, and NM-23). None of the 6 patients with STUMP experienced recurrent disease, whereas 8 of the 10 patients diagnosed with leiomyosarcoma died of disease at follow-up. The mean frequency of allelic loss (FAL) for leiomyomas (18%) was not significantly different from that of STUMPs (21%) (P = 1), whereas leiomyosarcomas displayed a significantly higher FAL (52%) than both leiomyomas (P = 0.001) and STUMPs (P = 0.002). Loss of NM-23, a reported tumor metastasis suppressor gene, was found only in leiomyosarcomas (5 of 9, or 56%), and 4 of 5 (80%) of these were the only cases that demonstrated distant metastases (P = 0.04). Additionally, an FAL of >50% correlated with both NM-23 loss (P = 0.008) and distant metastatic disease (P = 0.04). In conclusion, leiomyomas and STUMPs displayed similar mean FALs and all were clinically benign, whereas uterine leiomyosarcomas had significantly higher frequencies of allelic loss than both leiomyomas and STUMPs. Molecular profiling may thus provide a valuable tool in assessment of malignancy in uterine smooth muscle tumors. Additionally, NM-23 is a promising candidate gene for determination of metastatic potential in these tumors.

BRAF mutation is unusual in chronic lymphocytic thyroiditis-associated papillary thyroid carcinomas and absent in non-neoplastic nuclear atypia of thyroiditis

Chronic lymphocytic thyroiditis (CLT) has an epidemiological relationship to papillary thyroid carcinoma (PTC). The follicular epithelium in CLT can be markedly atypical, with cytologic changes ranging from oncocytic morphology to clearing and overlapping. At the molecular level, the association between CLT and PTC is more controversial. In order to further characterize the molecular changes in CLT, this study examined the BRAF gene in 27 patient samples with CLT and without carcinoma and 28 samples with CLT and carcinoma (12 conventional papillary carcinomas, 13 follicular variants, and 3 tall cell variants). Microdissection, PCR, and sequencing of exon 15 of the BRAF gene were performed. BRAF mutations were uncommon in the cases studied with only two microscopic and two clinically sized PTCs had BRAF mutations (14%). There was no evidence of BRAF mutation in any of the areas with atypical follicular epithelium in CLT. These data suggest that BRAF is a less frequent mechanism of tumorigenesis in a background of CLT and that BRAF mutation is not present in the atypical follicular epithelium of CLT.

Warthin Tumors Do Not Have Microsatellite Instability and Express Normal DNA Mismatch Repair Proteins

Context.—Warthin tumors are controversial entities with a poorly understood etiology. Although some investigators have suggested a neoplastic origin, others have supported a developmental anomaly. A recent study described the absence of staining for hMLH1 and hMSH2 proteins in the epithelial component of Warthin tumors, suggesting that they arise secondary to defects in the DNA mismatch repair system.

Objective.—To determine if Warthin tumors exhibit evidence of DNA mismatch repair defects.

Design.—Immunostains for hMLH1 and hMSH2 were performed using a standard approach. Microdissection of the epithelial component was followed by DNA extraction from the tissue fragments. Polymerase chain reaction and capillary electrophoresis analyses were performed for the following 5 National Cancer Institute–recommended microsatellites: D2s123, D5s346, D17s250, BAT25, and BAT26.

Patients.—Twelve patients with Warthin tumors were included.

Results.—The immunostains for hMLH1 and hMSH2 showed preserved expression in the nuclei of the epithelial component of all Warthin tumors. No microsatellite instability was detected, and no loss of heterozygosity was seen.

Conclusions.—These results are not concordant with previously reported results showing loss of expression of the hMLH1 and hMSH2 DNA mismatch repair enzymes in the epithelial component of Warthin tumors. Furthermore, no microsatellite instability was detected in the 5 loci tested for each tumor in this series. These data demonstrate that Warthin tumors do not have evidence of DNA mismatch repair defects at the genomic or protein expression level.

Nras loss induces metastatic conversion of Rb1-deficient neuroendocrine thyroid tumor

Mutations in the gene encoding the retinoblastoma tumor suppressor predispose humans and mice to tumor development. Here we have assessed the effect of Nras loss on tumor development in Rb1 heterozygous mice. Loss of one or two Nras alleles is shown to significantly reduce the severity of pituitary tumors arising in Rb1(+/-) animals by enhancing their differentiation. By contrast, C-cell thyroid adenomas occurring in Rb1(+/-) mice progress to metastatic medullary carcinomas after loss of Nras. In Rb1(+/-)Nras(+/-) animals, distant medullary thyroid carcinoma metastases are associated with loss of the remaining wild-type Nras allele. Loss of Nras in Rb1-deficient C cells results in elevated Ras homolog family A (RhoA) activity, and this is causally linked to the invasiveness and metastatic behavior of these cells. These findings suggest that the loss of the proto-oncogene Nras in certain cellular contexts can promote malignant tumor progression.

Recurrent sarcoidosis in lung transplant allografts: granulomas are of recipient origin

INTRODUCTION

Sarcoidosis accounts for only 2.8% of lung transplants in the United States. It is, however, the most commonly reported disease to recur after lung transplantation. In most cases, recurrence is diagnosed as an incidental finding in transbronchial lung allograft biopsy (TBLAB) and is unrelated to clinical or radiologic abnormalities. The origin of the histiocytes composing the noncaseating granulomas in the allograft lung in patients with recurrent sarcoidosis (RS) was analyzed using DNA identity testing in 4 cases.

MATERIAL AND METHODS

Native lung resections and corresponding transbronchial biopsies from patients who underwent lung transplantation for sarcoidosis between 1990 and 2004 and who developed RS were gathered from the paraffin block archives of University of Pittsburgh Medical Center. Clinical parameters including age, sex, grade of rejection, number of episodes of RS, and follow-up were recorded. Native lungs and corresponding TBLAB showing granulomas consistent with RS were microdissected in cases where adequate material was available. DNA was extracted, and an ABI AmpflSTR commercial kit was used to simultaneously amplify 15 short tandem repeat (STR) loci as well as 1 marker for the XY chromosomes. The informative STR loci in native lung (pure recipient), nongranulomatous donor lung, and granulomas in donor lung were analyzed in 4 patients. The relative proportion of donor and recipient cells in the chimera was quantified using the fluorescence intensity of each peak on an electropherogram. FISH analysis using probes targeted to X and Y chromosomes was performed in a case of sex-mismatched lung transplantation.

RESULTS

Eight patients with RS were identified. Two had bilateral lung transplantation, and the remaining 6 had single-lung transplantation. The age at transplantation ranged between 39 and 53. Five were females and 3 were men. Recurrent disease was diagnosed in 1 to 11 biopsies per patient and occurred first in the first 6 months following transplantation in 2 cases (25%), between 6 months and 1 year in 2 other cases (25%), and between 1 and 2 years in 4 cases (50%). In 4 patients, sufficient material allowed for DNA analysis. Amplification failed in 1 of the 4 cases, while the other 3 were successful. Patient 1 showed no ACR and granulomatous inflammation of RS in TBLAB. Donor (D) to recipient (R) profile changed from "normal" donor lung (37% D, 63% R) to 15% D and 85% R DNA in the granuloma. In patient 2, the TBLAB showed minimal ACR and granulomatous inflammation. D to R profile changed from 75% D and 25% R in the "normal" D lung to 54% D and 46% R in the granuloma. Patient 3 showed no ACR and RS in TBLAB. D to R profile changed from 85% D and 15% R in the "normal" D lung to 71% D and 29% R in the granuloma. FISH analysis showed a predominance of male cells of recipient origin.

CONCLUSIONS

DNA analysis of 3 cases of RS suggests that the presence of recurrent granulomas in the graft is associated with an increase in the percentage of recipient DNA in the epithelioid cell clusters, as confirmed by the FISH analysis of 1 case.

Controversial ectopic thyroid: a case report of thyroid tissue in the axilla and benign total thyroidectomy

A 43-year-old woman presented with a mass in her left axilla, which was surgically excised. Histologically, the tissue was a reactive lymph node with adjacent thyroid follicular tissue. The differential diagnosis included benign ectopic thyroid versus metastatic well-differentiated follicular-derived thyroid carcinoma. Because of the possibility of carcinoma, the patient underwent a diagnostic total thyroidectomy. The thyroid was grossly normal with no histologic evidence of malignancy. Post-operatively, the patient underwent a whole body 131I scan. Aside from an expected residual uptake in the thyroid bed region, there was no extrathyroidal uptake to suggest additional ectopic thyroid tissue or metastatic disease. At the time of this scan, her thyrotropin (TSH) was 92.8 microU/mL, thyroglobulin was less than 0.3 ng/mL, and thyroglobulin antibody was less than 3 IU/mL. Abnormalities in the embryologic development and migration of the thyroid gland can result in ectopic thyroid tissue. The most frequent locations are along the midline from the base of the tongue to the mediastinum. Only rare case reports exist of ectopic thyroid in other locations, including the chest (heart, trachea), abdomen (liver, gallbladder, pancreas), and pelvis (vagina). This case represents the first description of thyroid tissue in the axilla with a histologically benign thyroid gland.

Allelic loss in parathyroid neoplasia can help characterize malignancy

Parathyroid carcinoma can be difficult to diagnose, and the final pathologic diagnosis relies on clinicopathologic correlation. Clinical features of malignancy include high preoperative calcium levels and an intraoperative impression that the gland is adherent to local structures. Histologic features of malignancy include increased mitoses, vascular invasion, and broad bands of fibrosis. This study used molecular genotyping to assess parathyroid neoplasia for loss of heterozygosity across a panel of known tumor suppressor genes that have been previously identified as being important in the pathogenesis of parathyroid diseases. Parathyroid adenomas, hyperplasia, and carcinomas were included in the study, and a fractional allelic loss was calculated for each lesion. Losses of 1q25, 7q13.3, 10q23, 13q14.3, and 11p15.5 were particularly prevalent. In addition, almost all adenomas and carcinomas had loss of the markers for 1p. The benign parathyroid diseases (adenomas and hyperplasia) had low mean fractional allelic loss (11% and 15%, respectively). The parathyroid carcinomas, in contrast, showed high mean fractional allelic loss (63%). This difference in the mutational profile suggests that this type of assay may be useful as an adjunctive diagnostic test in cases of parathyroid neoplasia.

Molecular assessment of allelic loss in Warthin tumors

Warthin's tumors are benign lesions of the head and neck that have a characteristic morphologic appearance. The etiology of Warthin's tumors is controversial and whether they are true neoplasms or developmental malformations continues to be debated. In this study, we examined 12 Warthin tumors with a molecular and immunohistochemical approach. Immunostains for p53 and p16ink were performed. The epithelial and lymphoid components of each lesion were microdissected and PCR was performed for 13 microsatellite markers at or near common tumor suppressor genes. The results were analyzed semiquantitatively using capillary electrophoresis. Frequency of allelic loss was calculated. The epithelial component of all tumors was negative for p53 and p16ink. By molecular genotyping there was only one case that had one locus with allelic imbalance, while the remainder had no evidence of clonal allelic loss. The immunohistochemical and molecular results in this study lend support to the hypothesis that Warthin tumors are non-neoplastic, as there was no evidence of aberrant staining for tumor suppressor gene protein products and no evidence of consistent clonal allelic losses.

Unusual adrenal cortical tumor of unknown biologic potential: a nodule in a nodule in a nodule

Adrenocortical tumors are uncommon neoplasms in childhood. Most pediatric adrenal tumors are virilizing and carcinomas are more common than adenomas. Recent molecular data suggest an adenoma-to-carcinoma progression sequence in adrenal cortical neoplasms. We report a case of a 5-year-old boy who presented with virilizing symptoms secondary to an adrenal tumor that was resected laparoscopically. The bulk of the tumor was a large, yellow mass with typical features of an adrenal cortical adenoma. In the center was a well-circumscribed tan-brown nodule that was distinct from the adenoma and had oncocytic features. A third minute focus (3.0 mm) was noted that was not circumscribed or encapsulated, but showed marked pleomorphism and abundant mitoses, including atypical forms and increased Ki67 compared with the outer 2 nodules. Molecular analysis to assess the clonality and mutation rates of the 3 distinct areas showed only 2 genetic loci with allelic imbalances.

Immunophenotypic comparison of salivary gland oncocytoma and metastatic renal cell carcinoma

OBJECTIVES/HYPOTHESIS

The differential diagnosis of oncocytic neoplasms of salivary glands includes both primary and metastatic tumors, one of which is renal cell carcinoma. This study compared immunohistochemical staining characteristics of oncocytomas arising from salivary gland to metastatic renal cell carcinoma using a panel of markers.

STUDY DESIGN

Immunohistochemistry for cytokeratin 7 (CK7), cytokeratin 20 (CK20), epithelial membrane antigen (EMA), vimentin, CD10, and renal cell carcinoma marker (RCC) was performed on 10 oncocytomas and compared with ten metastatic renal cell carcinomas.

RESULTS

There were overlapping histologic findings in the oncocytomas and metastatic renal cell carcinomas, with oncocytomas displaying clear cell changes in 2 of 10 cases. CK7 was positive in 9 of 10 oncocytomas and CK20 in 8 of 10 (7/10 stained for both), and vimentin was only weakly positive in 4 of 10 oncocytomas. All oncocytomas were EMA positive, with membranous staining, and all were negative for CD10 and RCC. Metastatic renal cell carcinoma was strongly positive for vimentin, EMA, and CD10 in most cases. RCC and CK7 were variably positive in metastatic renal cell carcinomas (4/10), and only 1 of 10 showed weak staining with CK20.

CONCLUSIONS

Salivary gland oncocytomas and metastatic renal cell carcinomas share some similar histologic and immunohistochemical characteristics. CD10 and CK20 were the most useful markers to distinguish metastatic renal cell carcinoma from oncocytomas in the salivary gland, whereas RCC, EMA, CK7, and vimentin are not as useful.

Potential Diagnostic Use of p16INK4A, a New Marker That Correlates With Dysplasia in Oral Squamoproliferative Lesions

Protein products of tumor suppressor genes are often involved in regulating the cell cycle, and aberrant expression can correlate with underlying genetic mutations. Mutations in the p16 gene have been detected at relatively high rates in squamous cell carcinomas of the oral cavity. However, immunohistochemical staining for the protein product has not been examined as a diagnostic tool for identifying dysplastic lesions in the oral cavity. Sixty cases of biopsies of reactive, inflammatory, and dysplastic lesions of all grades were stained with an antibody to p16INK4A and analyzed for which layer of the epithelium had positive cells. Staining was seen only in the basal or lower third in keratoses and mild dysplasias and was seen in the mid and upper thirds in moderate to severe dysplasia. The staining across larger fragments of biopsied epithelium highlighted skip lesions, with strong staining restricted to dysplastic regions. Inflammatory lesions, including chronic ulcers, showed absent or minimal basal layer staining with p16INK4A. In this preliminary study, p16INK4A shows promise as to a potential marker to aid in recognizing the presence of dysplasia in squamous mucosa of the head and neck, particularly in subtle lesions, and in an inflammatory or ulcerated background.

Cultured podocytes establish a size-selective barrier regulated by specific signaling pathways and demonstrate synchronized barrier assembly in a calcium switch model of junction formation

Podocytes form unique cell-cell junctions (slit diaphragms) that are central to glomerular selectivity, although regulation and mechanisms of slit diaphragm assembly are poorly understood. With the use of cultured podocytes, a paracellular permeability flux assay was established to characterize properties of the size-selective barrier. Paracellular flux of differentiated podocytes was measured using anionic fluorescent dextrans of 3, 10, 40, and 70 kD. Podocytes form a highly selective barrier with a 160-fold difference in flux from the 3-kD dextran (11 pmol/min) to the 70-kD dextran (0.06 pmol/min). Barrier development was dependent on podocyte differentiation and not affected by dextran charge. Puromycin, a known podocyte toxin, increased flux 250% in a dose-dependent manner without affecting cell viability. Screening with modulators of specific signaling pathways identified reversible increases in flux with Src tyrosine and Rho kinase inhibition. The calcium switch model of epithelial junction assembly was modified to determine whether podocytes regulate barrier assembly. When cultured in low calcium for 90 min, flux increased by 300% and consistently returned to baseline 24 to 48 h after switching to normal calcium. Similar to classical epithelial junctions, barrier recovery occurred in the presence of cyclohexamide, an inhibitor of protein synthesis. During the calcium switch, there were reversible changes in localization and detergent solubility of the slit diaphragm protein ZO-1 and alpha-actinin-4, whereas nephrin and podocin solubility were unchanged. Taken together, these findings demonstrate that cultured podocytes develop a selective size barrier that is regulated by specific signaling pathways, and similar to classical epithelial junctions, podocytes demonstrate synchronized assembly of the barrier.

TLR4 and TNF-alpha polymorphisms are associated with an increased risk for severe sepsis following burn injury

CONTEXT

Sepsis, organ failure, and shock remain common among patients with moderate to severe burn injuries. The inability of clinical factors to identify at-risk patients suggests that genetic variation may influence the risk for serious infection and the outcome from severe injury.

OBJECTIVE

Resolution of genetic variants associated with severe sepsis following burn injury.

PATIENTS

A total of 159 patients with burns > or =20% of their total body surface area or any smoke inhalation injury without significant non-burn related trauma (injury severity score (ISS)> or =16), traumatic or anoxic brain injury, or spinal cord injury and who survived more than 48 h post-admission.

METHODS

Candidate single nucleotide polymorphisms (SNPs) within bacterial recognition (TLR4 +896, CD14 -159) and inflammatory response (TNF-alpha -308, IL-1beta -31, IL-6 -174) loci were evaluated for association with increased risk for severe sepsis (sepsis plus organ dysfunction or septic shock) and mortality.

RESULTS

After adjustment for age, full-thickness burn size, ethnicity, and gender, carriage of the TLR4 +896 G-allele imparted at least a 1.8-fold increased risk of developing severe sepsis following a burn injury, relative to AA homozygotes (adjusted odds ratio (aOR) 6.4; 95% confidence interval (CI) 1.8 to 23.2). Carriage of the TNF-alpha -308 A-allele imparted a similarly increased risk, relative to GG homozygotes (aOR = 4.5; 95% CI 1.7 to 12.0). None of the SNPs examined were significantly associated with mortality.

CONCLUSIONS

The TLR4 +896 and TNF-alpha -308 polymorphisms were significantly associated with an increased risk for severe sepsis following burn trauma.

Molecular Staging of Cervical Lymph Nodes in Squamous Cell Carcinoma of the Head and Neck

Clinical staging of cervical lymph nodes from patients with squamous cell carcinoma of the head and neck (SCCHN) has only 50% accuracy compared with definitive pathologic assessment. Consequently, both clinically positive and clinically negative patients frequently undergo neck dissections that may not be necessary. To address this potential overtreatment, sentinel lymph node (SLN) biopsy is currently being evaluated to provide better staging of the neck. However, to fully realize the potential improvement in patient care afforded by the SLN procedure, a rapid and accurate SLN analysis is necessary. We used quantitative reverse transcription-PCR (QRT-PCR) to screen 40 potential markers for their ability to detect SCCHN metastases to cervical lymph nodes. Seven markers were identified with good characteristics for identifying metastatic disease, and these were validated using a set of 26 primary tumors, 19 histologically positive lymph nodes, and 21 benign nodes from patients without cancer. Four markers discriminated between positive and benign nodes with accuracy >97% but only one marker, pemphigus vulgaris antigen (PVA), discriminated with 100% accuracy in both the observed data and a statistical bootstrap analysis. A rapid QRT-PCR assay for PVA was then developed and incorporated into a prototype instrument capable of performing fully automated RNA isolation and QRT-PCR. The automated analysis with PVA provided perfect discrimination between histologically positive and benign lymph nodes and correctly identified two lymph nodes with micrometastatic tumor deposits. These assays were completed (from tissue to result) in approximately 30 minutes, thus demonstrating the feasibility of intraoperative staging of SCCHN SLNs by QRT-PCR.

Human Leukocyte Antigen (HLA) Class I Defects in Head and Neck Cancer: Molecular Mechanisms and Clinical Significance

The potential role of immunological events in the pathogenesis and clinical course of head and neck squamous cell carcinoma (SCCHN) has stimulated interest in the characterization of HLA class I antigen expression in SCCHN lesions, because these molecules play an important role in the interaction of malignant cells with the host's immune system. Therefore in this paper, following a description of the methodology used to analyze HLA class I antigen expression in normal tissues and in malignant lesions, we have reviewed data about the frequency of HLA class I antigen defects in about 500 primary and in about 25 metastatic SCCHN lesions. The mean frequency of total HLA class I antigen loss in primary and metastatic lesions is approx 15% and 40%, respectively. The mean frequency of selective HLA class I antigen loss in primary lesions is approx 37%. This type of abnormality has not been investigated in metastatic lesions so far. The molecular mechanisms underlying HLA class I antigen defects in SCCHN cells have been investigated to a limited extent. The available information suggests that structural defects in beta2m genes are rare. In contrast, functional abnormalities of the antigen processing machinery (APM) components are frequent in SCCHN cells. The latter abnormalities are likely to account for the unusual finding that most of SCCHN cell lines are resistant in vitro to HLA class I antigen restricted, tumor antigen (TA)-specific CTL recognition under basal conditions in spite of the expression of TA and HLA class I antigens. CTL recognition of SCCHN cells is restored by incubation with IFN-gamma. These in vitro findings provide a mechanism for the association between APM component defects in SCCHN lesions and clinical course of the disease and imply that T cell-based immunotherapy of SCCHN may benefit from the intralesional administration of IFN-gamma.