Targeted next-generation sequencing of EUS-guided through-the-needle-biopsy sampling from pancreatic cystic lesions.

BACKGROUND AND AIMS: Recent advances have introduced molecular subtyping of pancreatic cystic lesions (PCLs) as a possible amendment to the diagnostic algorithm. The study evaluated the feasibility and diagnostic accuracy of molecular analysis and subtyping of PCLs using the recently introduced EUS-guided through-the-needle-biopsy (TTNB) sampling. METHODS: We prospectively included 101 patients in the study who presented with PCLs >15 mm in the largest cross-section. EUS-guided TTNB samples were obtained by a micro-biopsy forceps introduced through a 19-gauge needle. The TTNB samples were analyzed by next-generation sequencing (NGS) for point mutations in tumor suppressors and oncogenes using a 51-gene customized hotspot panel. Sensitivity and specificity were calculated with the histologic diagnosis as reference. RESULTS: After initial microscopic evaluation of the samples, 91 patients had residual TTNB samples available for NGS. Of these, 49 harbored mutations, most frequently in KRAS and GNAS, reflecting an excess frequency of intraductal papillary mucinous neoplasms (IPMNs) in the study population. A sensitivity and specificity of 83.7% (95% confidence interval [CI], 70.3-92.7) and 81.8% (95% CI, 48.2-97.7), respectively, were demonstrated for the diagnosis of a mucinous cyst and 87.2% (95% CI, 74.2-95.2) and 84.6% (95% CI, 54.5-98.1) for the diagnosis of an IPMN. CONCLUSIONS: Thus, molecular analysis of TTNB samples by NGS has high sensitivity and specificity for diagnosing mucinous cysts and IPMNs. Although the procedure comes with a risk of adverse events of 9.9%, TTNB samples are a robust alternative to cyst fluid for a combined histologic and molecular diagnosis of PCLs. (Clinical trial registration number: NCT03578445.).

Correlation of MET-Receptor Overexpression with MET Gene Amplification and Patient Outcome in Malignant Mesothelioma.

Thanks to clinically newly introduced inhibitors of the mesenchymal-epithelial transition (MET) receptor tyrosine-kinase, MET-gene copy number gain/amplification (MET-GCNG/GA) and increased expression of the MET protein are considered very promising therapeutic targets in lung cancer and other malignancies. However, to which extent these MET alterations occur in malignant mesothelioma (MM) remains unclear. Thus, we investigated by well-established immunohistochemistry and fluorescence in situ hybridization methods, the frequency of these alterations in specimens from 155 consecutive MMs of different subtypes obtained from pleural or peritoneal biopsies and pleurectomies. Thirty-three benign reactive mesothelial proliferations (RMPs) were used as controls. MET-protein upregulation was observed in 35% of all MM-cases, though restricted to predominantly epithelioid MMs. We detected low-/intermediate-level MET-GCNG/GA in 22.2% of MET-overexpressing MMs (7.8% of whole MM-cohort) and no MET-GCNG/GA in the other 77.8%, suggesting other upregulating mechanisms. In contrast, 100% of RMPs exhibited no MET-upregulation or MET-GCNG/-GA. Neither MET exon 14 skipping mutations nor MET-fusions were detected as mechanisms of MET overexpression in MM using RNA next-generation sequencing. Finally, in two cohorts of 30 MM patients with or without MET overexpression (MET-positive/-negative) that were matched for several variables and received the same standard chemotherapy, the MET-positive cases showed a significantly lower response rate, but no significant difference in progression-free or overall survival. Our results imply that MET overexpression occurs in a substantial fraction of predominantly epithelioid MMs, but correlates poorly with MET-amplification status, and may impact the likelihood of response to mesothelioma standard chemotherapy. The predictive significance of MET-IHC and -FISH for possible MET-targeted therapy of MM remains to be elucidated.

KRAS mutations in the parental tumour accelerate in vitro growth of tumoroids established from colorectal adenocarcinoma.

The aim of the present study was to characterize a patient-derived in vitro 3D model (ie tumoroid) established from colorectal adenocarcinoma. This study investigated the growth rate of tumoroids and whether the Kirsten rat sarcoma (KRAS) mutations in the parental tumour accelerate this rate. The tumoroids were established from surgical resections of primary and metastatic colorectal adenocarcinoma from 26 patients. The in vitro growth rate of these tumoroids was monitored by automated imaging and recorded as relative growth rate. The KRAS hotspot mutations were investigated on the parental tumours by Ion Torrent™ next-generation sequencing. The KRAS mutations were detected in 58% of the parental tumours, and a significantly higher growth rate was observed for tumoroids established from the KRAS-mutated tumours compared to wild-type tumours (P < 0.0001). The average relative growth rate (log10) on day 10 was 0.360 ± 0.180 (mean ± SD) for the KRAS-mutated group and 0.098 ± 0.135 (mean ± SD) for the KRAS wild-type group. These results showed that the presence of KRAS mutations in parental tumours is associated with an acceleration of the growth rate of tumoroids. The future perspective for such a model could be the implementation of chemoassays for personalized medicine.

Validation of the VisionArray® Chip Assay for HPV DNA Testing in Histology Specimens of Oropharyngeal Squamous Cell Carcinoma.

BACKGROUND: The detection of human papillomavirus (HPV) has several implications in the diagnostic work-up and management of oropharyngeal squamous cell carcinoma (OPSCC). The choice of HPV detection assay and testing algorithms differ across institutions and vary in cost, detection targets, technical feasibility, and turnaround time. In this study, we aimed to validate the VisionArray® HPV Chip for formalin-fixed and paraffin-embedded (FFPE) samples of OPSCC using the previously applied standard pan-HPV DNA PCR assay as a reference. METHODS: The validation cohort consisted of FFPE tissue samples from patients previously diagnosed with HPV DNA-positive OPSCC (n = 80), HPV DNA-negative OPSCC (n = 21), and a benign group of tumor samples consisting of Warthin's tumors (n = 20) and branchial cleft cysts of the lateral neck (n = 14). All samples were tested with p16 immunohistochemistry, pan-HPV DNA PCR, and the VisionArray® HPV Chip. RESULTS: The overall sensitivity and specificity of the VisionArray® HPV Chip assay were 100% [95% CI 95.5%; 100.0%] and 96.3% [95% CI 87.3%; 99.6%] and the positive predictive value and negative predictive value were 97.6% [95% CI 91.5%; 99.7%] and 100% [95% CI 93.2%; 100%], respectively. CONCLUSIONS: The VisionArray® HPV Chip assay can be recommended for high-risk HPV testing in FFPE tissue samples from OPSCC, providing both a fast and simultaneous genotyping for 41 clinically relevant HPV types.

DNA methylation profile of human dura and leptomeninges.

Healthy meninges are used as control tissue in meningioma studies usually without specification of the exact meningeal layer or macroanatomical origin but the DNA methylation profile of human meninges has not been investigated on a macroanatomical level. We undertook a proof-of-principle analysis to determine whether (1) meningeal tissues show sufficiently homogenous DNA methylation profiles to function as normal control tissue without further specification and (2) if previously described location-specific molecular signatures of meningiomas correspond to region-specific DNA methylation patterns. Dura mater and arachnoid membrane specimens were dissected from 5 anatomical locations in 2 fresh human cadavers and analyzed with the Illumina Infinium MethylationEPIC array. Dura and leptomeninges showed marked differences in global DNA methylation patterns and between rostral and caudal anatomical locations. These differences did not reflect known anatomical predilection of meningioma molecular signatures. The highest numbers of differentially methylated probes were annotated to DIPC2 and FOXP1. Samples from foramen magnum showed hypomethylation of TFAP2B compared to those from remaining locations. Thus, the DNA methylation profiles of human meninges are heterogenous in terms of meningeal layer and anatomical location. The potential variability of DNA methylation data from meningiomas should be considered in studies using meningeal controls.

Validation of a Novel EUS-FNB-Derived Organoid Co-Culture System for Drug Screening in Patients with Pancreatic Cancer.

Cancer-associated fibroblasts (CAFs) have been shown to impact the chemosensitivity of patient-derived tumor organoids (PDTOs). However, the published literature comparing PDTO response to clinical outcome does not include CAFs in the models. Here, a co-culture model was created using PDTOs and CAFs derived from endoscopic ultrasound-guided fine-needle biopsies (EUS-FNBs) for potential use in drug screening applications. Co-cultures were established, and growth was compared to monocultures using image metrics and a commercially available assay. We were able to establish and expand validated malignant PDTOs from 19.2% of adenocarcinomas from EUS-FNBs. CAFs could be established from 25% of the samples. The viability of PDTOs in the mixed cell co-culture could be isolated using image metrics. The addition of CAFs promoted PDTO growth in half of the established co-cultures. These results show that co-cultures can be established from tiny amounts of tissue provided by EUS-FNB. An increased growth of PDTOs was shown in co-cultures, suggesting that the present setup successfully models CAF-PDTO interaction. Furthermore, we demonstrated that standard validation techniques may be insufficient to detect contamination with normal cells in PDTO cultures established from primary tumor core biopsies.

PD-L1 expression and FGFR-mutations among Danish patients diagnosed with metastatic urothelial carcinoma: A retrospective and descriptive study.

Checkpoint inhibitors have changed the treatment landscape of advanced urothelial carcinoma (mUC), and recently, a fibroblast-growth-factor-receptor (FGFR) inhibitor has been introduced. This study aimed at estimating programmed death-ligand 1 (PD-L1) expression in primary tumors (PTs) and the PD-L1 expression concordance between PTs and paired metastases in 100 patients with UC managed in the real-world setting. Further, the aim was to investigate FGFR1-3 aberrations and the correlation between FGFR1-3 aberrations and PD-L1 expression. PD-L1 immunohistochemistry was performed on 100 formalin-fixed paraffin-embedded archival primary UC samples and 55 matched metastases using the 22C3 PD-L1 assay. PD-L1 expression was determined by the combined positive score, considered positive at ≥10. Targeted next-generation sequencing on the S5+/Prime System with the Oncomine Comprehensive Assay version 3 was used to detect FGFR1-3 aberrations in PTs. We found that 29 of 100 PTs had positive PD-L1 expression. The PD-L1 concordance rate was 71%. FGFR1-3 aberrations were observed in 18% of PTs, most frequently FGFR3 amplifications or mutations. We found no association between FGFR1-3 aberrations and PT PD-L1 expression (p = 0.379). Our data emphasize the need for further studies in predictive biomarkers.

Redefining germline predisposition in children with molecularly characterized ependymoma: a population-based 20-year cohort.

Ependymoma is the second most common malignant brain tumor in children. The etiology is largely unknown and germline DNA sequencing studies focusing on childhood ependymoma are limited. We therefore performed germline whole-genome sequencing on a population-based cohort of children diagnosed with ependymoma in Denmark over the past 20 years (n = 43). Single nucleotide and structural germline variants in 457 cancer related genes and 2986 highly evolutionarily constrained genes were assessed in 37 children with normal tissue available for sequencing. Molecular ependymoma classification was performed using DNA methylation profiling for 39 children with available tumor tissue. Pathogenic germline variants in known cancer predisposition genes were detected in 11% (4/37; NF2, LZTR1, NF1 & TP53). However, DNA methylation profiling resulted in revision of the histopathological ependymoma diagnosis to non-ependymoma tumor types in 8% (3/39). This included the two children with pathogenic germline variants in TP53 and NF1 whose tumors were reclassified to a diffuse midline glioma and a rosette-forming glioneuronal tumor, respectively. Consequently, 50% (2/4) of children with pathogenic germline variants in fact had other tumor types. A meta-analysis combining our findings with pediatric pan-cancer germline sequencing studies showed an overall frequency of pathogenic germline variants of 3.4% (7/207) in children with ependymoma. In summary, less than 4% of childhood ependymoma is explained by genetic predisposition, virtually restricted to pathogenic variants in NF2 and NF1. For children with other cancer predisposition syndromes, diagnostic reconsideration is recommended for ependymomas without molecular classification. Additionally, LZTR1 is suggested as a novel putative ependymoma predisposition gene.

Extra-axial chordoma of the thumb: Report of a rare case with clinicopathologic and molecular analysis.

Chordoma is a very rare malignant tumor, with a phenotype that recapitulates notochord, and is chiefly located in the axial skeleton with only few cases reported in the extra-axial skeleton and soft tissues. The diagnosis can be challenging for both clinicians, radiologists and pathologists because of the rarity of tumor, its unspecific radiological pattern and histomorphological similarities to other tumors like extra-skeletal myxoid chondrosarcoma, soft tissue myoepithelioma and metastatic adenocarcinomas, more so on small biopsies. We present a case of a recurrent extra-axial chordoma with a prominent soft tissue component in the left thumb around proximal phalanx of an 80-year-old man, with detailed report of the histopathological, imaging and most importantly molecular features, which are in conformity with the typical profile of notochordal neoplasms. To the best of our knowledge, we report the first DNA-methylation- and the copy number variation analysis of an extra-axial chordoma with a very rare localization, thumb. With this case study we try to give a better understanding of tumor's specification, lessen the diagnostic confusion by highlighting its extra-axial occurrence, and more importantly present substantial molecular data, which might help in providing more therapeutic opportunities in the future.

Molecular heterogeneity of pancreatic intraductal papillary mucinous neoplasms and implications for novel endoscopic tissue sampling strategies.

AIMS: Intraductal papillary mucinous neoplasms (IPMNs) may be precursor lesions of pancreatic cancer. The path towards malignancy is associated with mutations in tumour suppressor-and oncogenes that may serve as biomarkers during diagnostic investigation. A novel micro forceps has made it possible to obtain biopsies from the cyst wall for analysis by next generation sequencing (NGS), providing an opportunity for early detection and intervention. However, the impact of spatial tumour heterogeneity on the representability of the biopsies has not been determined. The primary aim is to characterise the impact of molecular heterogeneity of the luminal cyst wall on tissue sampling strategies with small biopsies. METHODS: We performed NGS and immunohistochemical phenotyping on 18 resected IPMNs with varying degrees of dysplasia and for a subset, concomitant carcinoma, using a commercially available NGS-panel of 51 oncogenes. We simulated endoscopic biopsies by performing punch biopsies (PBs) of the cyst wall from resected specimens. RESULTS: In total, 127 NGS analyses were performed. Concomitant KRAS and GNAS was a common feature of the IPMNs. Mutations in KRAS and GNAS were associated with low-grade dysplasia whereas alterations in TP53, SMAD4, CDKN2A and PIK3CA were associated with high-grade dysplasia and/or carcinoma. The mutational analysis of the PBs from the cyst wall was compared with the whole lesion. No difference was detected between PBs and whole lesions when the cumulated mutational profile in increasing order of randomly performed PBs was compared. CONCLUSIONS: Small IPMN biopsies from the cyst wall are adequate to yield a molecular diagnosis.

The molecular profile of mucosal melanoma.

Herein, we wanted to explore the molecular landscape of mucosal melanoma from different sites and identify potential molecular targets for future therapy. Mucosal melanomas (N = 40) from different sites (conjunctiva, sinonasal cavity, rectum, and vagina) were investigated. Targeted next-generation sequencing along with Nanostring gene expression profiling was performed. Genetically, conjunctival melanoma was characterized by BRAF-V600E (30%) and NF1 mutations (17%). Mucosal melanomas at nonsun-exposed sites harbored alterations in NRAS, KIT, NF1, along with atypical BRAF mutations. When comparing the gene expression profile of conjunctival melanoma and nonsun-exposed mucosal melanoma, 41 genes were found to be significantly deregulated. Programmed death-ligand 1 (PD-L1) presented a significant sixfold upregulation in conjunctival melanoma compared to the other mucosal melanomas. While melanomas of the sinonasal cavity, vagina, and rectum are molecularly similar, conjunctival melanoma is characterized by a higher frequency of BRAF-V600E mutations and differential expression of several genes involved in the immune response.

A Novel Eight Octapeptide Repeat Insertion in PRNP Causing Prion Disease in a Danish Family.

Octapeptide repeat insertions (OPRI) found in the prion protein gene (PRNP) constitute a subgroup of pathogenic mutations linked to inherited prion diseases, a hallmark of which is a misfolded prion protein. The number of repeats in OPRI has been associated with different disease phenotypes. However, due to the rarity of the cases and heterogenous disease manifestations, the recognition and classification of these variants has been difficult. Here, we report the first Danish family, the fifth worldwide, carrying a novel 8-OPRI with a unique sequence of the additional 8 inserts: R1-R2-R2-R3-R2-R2-R2a-R2-R3g-R2-R2-R3-R4. The mutation was found on the allele coding for methionine at codon 129 in the PRNP gene. The clinical exome sequencing revealed that no other dementia-associated genes harbored pathogenic alterations. Mutation carriers had onset of symptoms in their early thirties, but disease duration varied from 5 to 11 years. Progressive dementia with psychiatric and motor symptoms were the most prominent clinical features. Clinical, pathological, and genetic characteristics of other 4 reported families with 8-OPRI were reviewed and compared with the findings in the Danish family.

An update on head and neck cancer: new entities and their histopathology, molecular background, treatment, and outcome.

The head and neck region harbor numerous specialized tissues of all lineages giving rise to a plethora of different malignancies. In recent years, new types and subtypes of cancer has been described here due to the recognition of their histological and molecular characteristics. Some have been formally accepted in the most recent classifications from the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) as distinct diseases due to characteristics in clinical presentation, outcome, and treatment. In particular, this applies to malignancies of the salivary gland, sinonasal tract, and oropharynx. In this overview, we present the most recent developments in the classification, histopathological characteristics, and molecular features of head and neck cancer. The clinical and radiological characteristics, outcome, and treatment options including perspectives for targeted therapies, are discussed.

Primary and secondary mucosal melanoma of the small intestine - a clinical, pathological, and genetic nationwide survey of Danish patients between 1980 and 2014.

The aim of this study was to describe the epidemiology, symptomatology, pathology, genetics, and treatment of primary and metastatic small intestine melanoma in a national Danish cohort. All Danish patients diagnosed with small intestinal melanoma during the period 1980-2014 were included. For each patient, clinical data along with available pathology report and tissue was registered. Targeted next-generation sequencing (NGS) of known hotspots in 50 oncogenic genes was performed. Twenty patients with small intestinal melanoma were retrieved. Eight of these were primary melanomas. The median age was 66 years for primary melanoma patients and 58 years for secondary melanoma patients. The male/female ratio (M/F) was 3:1 for primary melanoma and 1:1 for secondary melanoma. The median time of survival was 3.5 months and 9 months for primary and secondary melanoma patients, respectively. NGS of primary tumours showed polymorphisms in the HRAS, PI3KCA, and JAK3 genes. Primary mucosal melanoma of the small intestines is a very rare disease, with an incidence of 0.04 cases/million/year in Denmark. Patients aged 59-70 years with abdominal symptoms should make the clinician consider a small bowel melanoma as a differential diagnosis. The prognosis ranged from less than a month to 183.6 months.

The PRKD1 E710D hotspot mutation is highly specific in separating polymorphous adenocarcinoma of the palate from adenoid cystic carcinoma and pleomorphic adenoma on FNA.

BACKGROUND: Polymorphous adenocarcinoma (PAC) of the palatal minor salivary glands, previously known as polymorphous low-grade adenocarcinoma, is the second most common intraoral malignant salivary gland carcinoma after adenoid cystic carcinoma (ACC) and carries an excellent prognosis. Unfortunately, PAC demonstrates cytological overlap with 2 other salivary gland tumors frequently encountered in the same location, namely ACC and pleomorphic adenoma (PA). Recently, the protein kinase D1 (PRKD1) hotspot mutation E710D was demonstrated to be specific for PAC and to be present in the majority of cases. The objective of the current study was to investigate the value of PRKD1 hotspot sequencing in identifying PAC in paired fine-needle aspiration (FNA) and surgical specimens from cases of PAC, ACC, and PA. METHODS: Paired May-Grunwald-Giemsa-stained FNA and corresponding surgical specimens were collected from 18 PAC cases, 25 ACC cases, and 21 PA cases. Both sets of specimens were subjected to dideoxynucleotide sequencing of PRKD1 exon 15, including the PRKD1 E710D hotspot. RESULTS: Of the PAC cases, approximately 50% demonstrated identical PRKD1 E710D hotspot mutations on the FNA specimen and corresponding surgical specimen. Two ACC specimens had point mutations within the sequenced region in the FNA specimen as well as the surgical specimen, but none were located in the hotspot region. None of the PA cases demonstrated PRKD1 mutations. The specificity of the PRKD1 hotspot mutation for identifying PAC among ACC and PA cases was 100% whereas the sensitivity was 50%. CONCLUSIONS: The PRKD1 E710D hotspot mutation is highly specific for identifying PAC on FNA among cases of ACC and PA, whereas the sensitivity is only modest. Alternative PRKD1 mutations exclude PAC, and are more suggestive of ACC. Cancer Cytopathol 2018;126:275-81. © 2017 American Cancer Society.

Sporadic Creutzfeldt-Jakob Disease in a Woman Married Into a Gerstmann-Sträussler-Scheinker Family: An Investigation of Prions Transmission via Microchimerism.

This is the first report of presumed sporadic Creutzfeldt-Jakob disease (sCJD) and Gerstmann-Sträussler-Scheinker disease (GSS) with the prion protein gene c.305C>T mutation (p.P102L) occurring in one family. The father and son were affected with GSS and the mother had a rapidly progressive form of CJD. Diagnosis of genetic, variant, and iatrogenic CJD was ruled out based on the mother's clinical history, genetic tests, and biochemical investigations, all of which supported the diagnosis of sCJD. However, given the low incidence of sCJD and GSS, their co-occurrence in one family is extraordinary and challenging. Thus, a hypothesis for the transmission of infectious prion proteins (PrPSc) via microchimerism was proposed and investigated. DNA from 15 different brain regions and plasma samples of the CJD patient was subjected to PCR and shallow sequencing for detection of a male sex-determining chromosome Y (chr. Y). However, no trace of chr. Y was found. A long CJD incubation period or presumed small concentrations of chr. Y may explain the obtained results. Further studies of CJD and GSS animal models with controlled genetic and proteomic features are needed to determine whether maternal CJD triggered via microchimerism by a GSS fetus might present a new PrPSc transmission route.

Genetic rearrangements, hotspot mutations, and microRNA expression in the progression of metastatic adenoid cystic carcinoma of the salivary gland.

Adenoid cystic carcinoma (ACC) is among the most common salivary gland malignancies, and is notorious for its unpredictable clinical course with frequent local recurrences and metastatic spread. However, the molecular mechanisms for metastatic spread are poorly understood. This malignancy is known to frequently harbor gene fusions involving MYB, MYBL1, and NFIB, and to have a low mutational burden. Most studies have focused on primary tumors to understand the biology of ACC, but this has not revealed a genetic cause for metastatic dissemination in the majority of cases. Hence, other molecular mechanisms are likely to be involved. Here, we characterize the genetic and microRNA expressional landscape of primary ACC and corresponding metastatic lesions from 11 patients. FISH demonstrated preservation of MYB aberrations between primary tumors and metastases, and targeted next-generation sequencing identified mutations exclusive for the metastatic lesions in 3/11 cases (27.3%). Global microRNA profiling identified several differentially expressed miRNAs between primary ACC and metastases as compared to normal salivary gland tissue. Interestingly, individual tumor pairs differed in miRNA profile, but there was no general difference between primary ACCs and metastases. Collectively, we show that MYB and NFIB aberrations are consistently preserved in ACC metastatic lesions, and that additional mutations included in the 50-gene hotspot panel used are infrequently acquired by the metastatic lesions. In contrast, tumor pairs differ in microRNA expression and our data suggest that they are heterogeneous according to their microRNA profile. This adds an additional layer to the complex process of ACC metastatic spread.

Appendicitis Caused by Primary Varicella Zoster Virus Infection in a Child with DiGeorge Syndrome.

INTRODUCTION: Chickenpox is caused by varicella zoster virus (VZV). Although predominantly a mild disease, it can cause considerable morbidity and in rare occasions even mortality in healthy children as well as increased morbidity and mortality in immunocompromised patients. The aetiology of appendicitis is largely unknown but is thought to be multifactorial. Appendicitis is a suspected, but not well documented, complication from varicella zoster virus infection. CASE PRESENTATION: A five-year-old girl diagnosed with DiGeorge syndrome and a prolonged primary VZV infection was admitted due to abdominal pain, increasing diarrhoea, vomiting, and poor general condition. She developed perforated appendicitis and an intraperitoneal abscess. VZV DNA was detected by PCR in two samples from the appendix and pus from the abdomen, respectively. The child was treated with acyclovir and antibiotics and the abscess was drained twice. She was discharged two weeks after referral with no sequela. CONCLUSION: Abdominal pain in children with viral infections can be a challenge, and appendicitis has to be considered as a complication to acute viral diseases, especially if the child is immunocompromised.

Genomic and immunohistochemical characterisation of a lacrimal gland oncocytoma and review of literature.

The aim of the present study was to report the genetic and immunohistochemical profile of a rare case of lacrimal gland oncocytoma. A 20-year-old male underwent magnetic resonance imaging (MRI) due to viral encephalitis. Notably, the MRI revealed a multicystic tumor in the left lacrimal gland. A lateral orbitotomy was performed and the tumor was completely excised. Four months following surgery, the patient was free of symptoms. Histopathologically, the tumor was composed of large, eosinophilic and polyhedral cells with small round nuclei. The tumor cells stained strongly for antimitochondrial antibody MU213-UC, cytokeratin (CK) 5/6, CK 7, CK 17, CK 8/18 and CK 19. The final diagnosis was an oncocytoma of the lacrimal gland without any signs of malignancy. Array-based comparative genomic hybridisation demonstrated a gain of one copy of chromosome 8 and loss of one copy of chromosome 22 as the sole genomic imbalances. These chromosomal alterations have not previously been identified in oncocytoma and may be specific to lacrimal gland oncocytoma. Sequencing of the mitochondrial genome demonstrated multiple alterations of the NADH-ubiquinone oxidoreductase chain 5 (ND5) gene involved in mitochondrial oxidative phosphorylation. This may support the notion of a common genetic background of oncocytic lesions in the lacrimal gland and other anatomical sites.