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Myoepithelial carcinoma of salivary glands is an underrecognized and challenging entity with a broad morphologic spectrum, including an EWSR1-rearranged clear cell variant. Myoepithelial carcinoma is generally aggressive with largely unknown genetic features. A retrospective review of Salivary Gland Tumor Registry in Pilsen searching for the key words "clear cell myoepithelial carcinoma," "hyalinizing clear cell," and "clear cell malignant myoepithelioma" yielded 94 clear cell myoepithelial carcinomas (CCMCs) for molecular analysis of EWSR1 rearrangement using fluorescence in situ hybridization (FISH). Tumors positive for EWSR1 gene rearrangement were tested by next-generation sequencing (NGS) using fusion-detecting panels. NGS results were confirmed by reverse-transcription polymerase chain reaction or by FISH. Twenty-six tumors originally diagnosed as CCMC (26/94, 27.6%) revealed split signals for EWSR1 by FISH. Six of these tumors (6/26, 23%) displayed amplification of the EWSR1 locus. Fifteen cases were analyzable by NGS, whereas 9 were not, and tissue was not available in 2 cases. None of the CCMCs with EWSR1 rearrangements detected by FISH had an EWSR1 fusion transcript. Fusion transcripts were detected in 6 cases (6/15, 40%), including LIFR-PLAG1 and CTNNB1-PLAG1, in 2 cases each, and CHCHD7-PLAG1 and EWSR1-ATF1 fusions were identified in 1 case each. Seven cases, including those with PLAG1 fusion, were positive for PLAG1 rearrangement by FISH, with notable exception of CHCHD7-PLAG1, which is an inversion not detectable by FISH. One single case with EWSR1-ATF1 fusion in NGS showed ATF1 gene rearrangement by FISH and was reclassified as clear cell carcinoma (CCC). In addition, another 4 cases revealed ATF1 rearrangement by FISH and were reclassified as CCC as well. Moreover, 12/68 (17%) CCMCs with intact EWSR1 gene were selected randomly and analyzed by NGS. PLAG1 fusions were found in 5 cases (5/12, 41.6%) with LIFR (2 cases), FGFR1 (2 cases), and CTNNB1 (1 case) as partner genes. Overall, PLAG1 gene rearrangements were detected in 10/38 (26%) tested cases. None of the tumors had SMARCB1 loss by immunohistochemistry as a possible explanation for the EWSR1 abnormalities in FISH. Novel findings in our NGS study suggest that EWSR1-FISH positive CCMC is a gene fusion-driven disease with frequent oncogenic PLAG1 fusions, including LIFR-PLAG1 and CTNNB1-PLAG1 in most cases. Productive EWSR1 fusions are found only in a minority of EWSR1-ATF1-rearranged cases, which were in part reclassifiable as CCCs. Detectable EWSR1-FISH abnormality in CCMCs without gene fusion perhaps represents a passenger mutation with minor or no oncologic effect.

Salivary gland carcinomas represent a heterogeneous group of poorly characterized head and neck tumors. The purpose of this study was to evaluate ALK gene and protein aberrations in a large, well-characterized cohort of these tumors. A total of 182 salivary gland carcinomas were tested for anaplastic lymphoma kinase (ALK) positivity by immunohistochemistry (IHC) using the cut-off of 10% positive cells. ALK positive tumors were subjected to FISH analysis and followed by hybrid capture–based next generation sequencing (NGS). Of the 182 tumors, 8 were ALK positive by IHC. Further analysis using hybrid capture NGS analysis revealed a novel MYO18A (Exon1-40)-ALK (exon 20-29) gene fusion in one case of intraductal carcinoma. Additional genomic analyses resulted in the detection of inactivating mutations in BRAF and TP53, as well as amplifications of ERBB2 and ALK. ALK rearrangements are a rare entity in salivary gland carcinomas. We identified a potentially targetable novel ALK fusion in an intraductal carcinoma of minor salivary glands.

The etiology of sarcoidosis is unknown, but microbial agents are suspected as triggers.We sought to identify bacterial, fungal, or viral lineages in specimens from patients with sarcoidosis enriched relative to control subjects using metagenomic DNA sequencing. Because DNA from environmental contamination contributes disproportionately to samples with low authentic microbial content, we developed improved methods for filtering environmental contamination.We analyzed specimens from subjects with sarcoidosis (n = 93), control subjects without sarcoidosis (n = 72), and various environmental controls (n = 150). Sarcoidosis specimens consisted of two independent sets of formalin-fixed, paraffin-embedded lymph node biopsies, BAL, Kveim reagent, and fresh granulomatous spleen from a patient with sarcoidosis. All specimens were analyzed by bacterial 16S and fungal internal transcribed spacer ribosomal RNA gene sequencing. In addition, BAL was analyzed by shotgun sequencing of fractions enriched for viral particles, and Kveim and spleen were subjected to whole-genome shotgun sequencing.In one tissue set, fungi in the Cladosporiaceae family were enriched in sarcoidosis compared with nonsarcoidosis tissues; in the other tissue set, we detected enrichment of several bacterial lineages in sarcoidosis but not Cladosporiaceae. BAL showed limited enrichment of Aspergillus fungi. Several microbial lineages were detected in Kveim and spleen, including Cladosporium. No microbial lineage was enriched in more than one sample type after correction for multiple comparisons.Metagenomic sequencing revealed enrichment of microbes in single types of sarcoidosis samples but limited concordance across sample types. Statistical analysis accounting for environmental contamination was essential to avoiding false positives.

Aim The aim of the study was to assess the watch&wait strategy for management of patients with close surgical margin after conservative parotidectomy due to early low/intermediate grade parotid carcinoma. Patients and methods Out of 78 patients operated on due to primary parotid gland cancer we selected 32 patients with a history of parotidectomy, and preservation of 7th nerve, with negative (≥1 mm), but close (≤5 mm) surgical margin and who did not receive supplementary radiotherapy due to other indications. Margins ranged from 1 to 3 mm (in 27 cases it was 1 mm, in 3 cases – 2 mm and in 2 cases – 3 mm), average 1.2 mm. The patients underwent further clinical-histological analysis. Results 3 of 32 (9.38%) patients experienced a local recurrence 36, 53 and 56 months post-surgery. The 5-year disease-free survival (DFS) was 90.6%. Recurrences were treated surgically, followed by radiotherapy, which resulted in an overall survival of 107, 104 and 104 months. One patient died 72 months after surgery due to non-oncological causes. The 10-year disease-free survival (DFS) was 96.3%. The 3 patients with recurrence of cancer had histological diagnosis of epithelial-myoepithelial carcinoma LG, with a margin of 2, 1 and 3 mm, respectively. There were no other distinctive features. Conclusion The watch&wait strategy with intensive follow-up seems justified in cases of close margin after excision of I/LG T1/T2 parotid tumors. EMC should be considered as a neoplasm associated with higher risk of recurrence.

The present study was undertaken to evaluate real probability and pattern of cervical occult lymph node metastases (OLNM) in primary parotid carcinoma (PPC). We carried out a retrospective analysis of 66 patients treated in years 1992–2010 due to PPC, who underwent elective neck dissection (END). In search of risk factors for OLNM, we analysed the following parameters: age, sex, pT-Status, tumour size, skin invasion, facial nerve palsy, tumour fixation, extraparotid extension, localization, grade, histology, intra/periparotid LN metastases (IPLNM). OLNM was observed in 30.3% of patients. In a univariate analysis statistical significance was found for IPLNM, extraparotid extension and high risk histology. A multivariate analysis showed statistical significance only for the first variable. The most common location of cervical OLNM was level II (80%), then III (45%) and V (30%). In a compilation of our own material with data from the literature (5 series), we obtained a group of 80 patients with OLNM, selected out of 650 patients with cN0 (12.3%). The proportion of metastases to particular levels was the following: 69%—II, 22.5%—III, 20%—I,16%—V, 7.5%—IV. END should be carried out in case of all T3/T4a carcinomas with minimal range of levels II and III. Removal of levels Ib and Va is recommended as well. In the T1/T2 carcinomas with high grade/high risk histology, END should be performed including levels II and III.

Metastatic tumors involving salivary glands arising from the non-head and neck area are very rare. Renal cell carcinoma (RCC) is known for its high propensity for metastasis to unusual localizations. RCC metastasis to the maxillofacial area is an uncommon event (16%), but metastasis to salivary glands is extremely rare. We report a series of 9 such cases retrieved from two institutions. The group included 6 females and 3 males. The age at diagnosis ranged from 60 to 97 years (mean 72.6 years). The tumors involved the parotid gland in 7 cases, and the submandibular and small salivary gland of the oral cavity in 1 case each. The size of tumors ranged from 0.4 to 5 cm. Total parotidectomy with selective neck dissection was performed in 4 cases, while superficial parotidectomy was performed in 1 case and simple resection in 3 cases. Histologically, all the tumors were clear cell renal cell carcinomas, and therefore the differential diagnosis mainly included clear cell variants of salivary gland carcinomas. The parotid gland was the initial manifestation of renal malignancy in 4 of the cases, while in the remaining 5 cases a history of RCC had been known. The salivary gland involvement developed from 11 months to 13 years after the time of diagnosis of the primary tumor. In 2 cases it was the first site of dissemination. Pathologists need to maintain a high index of suspicion for the possibility of metastasis when confronted with oncocytic or clear cell neoplasms developing in salivary glands. RCC, although rare, should be included in this differential diagnosis.

Bones are the most common metastatic site of relapse in breast cancer patients and the prediction of bone metastases (BM) risk might prompt developing preventive and therapeutic strategies. The aim of the study was to correlate imumohistochemical (IHC) expression of selected proteins in primary breast cancer with the occurrence of BM. We analyzed expression of proteins potentially associated with BM in primary tumors of 184 patients with metastatic breast cancer (113 with- and 71 without BM). Expression of estrogen receptor (ER) in primary tumor was more common in patients with- compared to those without BM (74 vs. 45 % respectively, p = 0.0001), whereas in this subset less common was expression of parathyroid hormone related protein receptor type 1 (16 vs. 34 %, respectively, p = 0.007) and cytoplasmic expression of osteopontin (OPNcyt; 1.9 vs. 14 %, respectively, p = 0.002). The relationship between expression of ER and OPNcyt and the occurrence of BM was confirmed in the multivariate analysis. The ER-positive/OPNcyt negative phenotype was significantly more common in patients with- compared to those without BM (75 and 25 %, p

This study examines the presence of the EWSR1 rearrangement in a variety of clear cell salivary gland carcinomas with myoepithelial differentiation. A total of 94 salivary gland carcinomas with a prominent clear cell component included 51 cases of clear cell myoepithelial carcinomas de novo (CCMC), 21 cases of CCMCs ex pleomorphic adenoma (CCMCexPA), 11 cases of epithelial-myoepithelial carcinoma (EMC), 6 cases of EMC with solid clear cell overgrowth, and 5 cases of hyalinizing clear cell carcinoma of minor salivary glands. In addition, 10 cases of myoepithelial carcinomas devoid of clear cell change and 12 cases of benign myoepithelioma were included as well. All the tumors in this spectrum were reviewed, reclassified, and tested by fluorescence in situ hybridization (FISH) for the EWSR1 rearrangement using the Probe Vysis EWSR1 Break Apart FISH Probe Kit. The EWSR1 rearrangement was detected in 20 of 51 (39%) cases of CCMC, in 5 of 21 (24%) cases of CCMCexPA, in 1 of 11 (9%) cases of EMC, and in 4 of 5 (80%) cases of hyalinizing clear cell carcinoma. The 25 EWSR1-rearranged CCMCs and CCMCexPAs shared similar histomorphology. They were arranged in nodules composed of compact nests of large polyhedral cells with abundant clear cytoplasm. Necrosis, areas of squamous metaplasia, and hyalinization were frequent features. Immunohistochemically, the tumors expressed p63 (96%), cytokeratin CK14 (96%), and S100 protein (88%). MIB1 index varied from 10% to 100%, with most cases in the 20% to 40% range. Clinical follow-up information was available in 21 cases (84%) and ranged from 3 months to 15 years (mean 5.2 y); 4 patients were lost to follow-up. Ten patients are alive with no evidence of recurrent or metastatic disease in the follow-up period from 3 months to 15 years (mean 5 y), 3 patients are alive with recurrent and metastatic disease, and 8 died of disseminated cancer 9 months to 16 years after diagnosis (mean 6 y). Lymph node metastasis appeared in 5 patients within 5 months to 4 years after diagnosis (mean 22 mo), distant metastases were noted in 7 patients with invasion of orbit (2 cases), and in 1 case each metastasis to the neck soft tissues, liver, lungs, mediastinum, and thoracic vertebra was noted. We describe for the first time EWSR1 gene rearrangement in a subset of myoepithelial carcinomas arising in minor and major salivary glands. The EWSR1-rearranged CCMC represents a distinctive aggressive variant composed predominantly of clear cells with frequent necrosis. Most EWSR1-rearranged CCMCs of salivary glands are characterized by poor clinical outcomes.

Whilst the role of eukaryotic translation initiation factors (eIFs) has already been investigated in several human cancers, their role in endometrial cancer (EC) is relatively unknown. In the present retrospective study, 279 patients with EC (1180 samples) were included (mean age: 63.0 years, mean follow-up: 6.1 years). Samples were analysed for expression of 7 eIFs subunits (eIF2&alpha, eIF3c, eIF3h, eIF4e, eIF4g, eIF5, eIF6) through immunohistochemistry and western blotting. Fifteen samples of healthy endometrium served as controls. Density and intensity were assessed and mean combined scores (CS) calculated for each patient. Upon immunohistochemistry, median eIF5 CS were significantly higher in EC as compared with non-neoplastic tissue (NNT, p &lt, 0.001), whilst median eIF6 CS were significantly lower in EC (p &lt, 0.001). Moreover, eIF5 (p = 0.002), eIF6 (p = 0.032) and eIF4g CS (p = 0.014) were significantly different when comparing NNT with EC grading types. Median eIF4g CS was higher in type II EC (p = 0.034). Upon western blot analysis, eIF4g (p &lt, 0.001), peIF2&alpha, (p &lt, 0.001) and eIF3h (p &lt, 0.05) were significantly overexpressed in EC, while expression of eIF3c was significantly reduced in EC as compared with NNT (p &lt, 0.001). The remaining eIFs were non-significant. Besides tumour stage (p &lt, 0.001) and patient&rsquo, s age (p &lt, 0.001), high eIF4g CS-levels were independently associated with poor prognosis (HR: 1.604, 95%CI: 1.037&ndash, 2.483, p = 0.034). The other eIFs had no prognostic significance. Notably, the independent prognostic significance of eIF4g was lost when adding tumour type. Considering the difficulties in differentiating EC type I and II, eIF4g may serve as a novel prognostic marker indicating patient outcome.

Background There are no clinically useful biomarkers predictive of brain metastases (BM) in breast cancer. In this study, we investigated the correlation between expression of selected proteins in the primary tumor and the risk of BM in patients with metastatic breast cancer (MBC). Methods The study included 198 MBC patients (96 with and 102 without BM). Using tissue microarrays derived from the primary tumor, we assessed by immunohistochemical expression of ER, PR, HER2, Ki-67, CK5/6, EGFR, HER3, CXCR4, Rad51, E-cadherin, and claudin 3 and 4. Results Ki-67 ≥14% (hazard ratio [HR] 2.76; P P = 0.014) and ER-negativity (HR 1.72; P = 0.029) were associated with increased risk of BM in the multivariate analysis. A three-biomarker profile including ER, Ki-67 and Rad51 vs. other subtypes combined yielded an HR of 4.43 ( P Conclusions ER-negativity, cytoplasmic expression of Rad51 and high Ki-67 are associated with increased risk of BM.

The molecular background of endometrial cancer (EC) has not been fully elucidated. In the present study, we developed a quantitative PCR (qPCR) platform to examine the gene dosages of the potential molecular markers MGB1, TOP2A, ERBB1-4, MYC, CCND1, ESR1 and PI3K. The platform was applied in samples collected from 157 EC patients (stage I-IV) to verify its clinical utility and to examine the diagnostic and prognostic significance of the analysed biomarkers. The gene dosage pattern of the ERBB family and its downstream effectors PI3K and MYC showed particularly strong correlations with clinicopathological data. The ERBB PI3K/Akt pathway was upregulated in 31 (20%) of 156 cases. Activation of the ERBB PI3K/Akt pathway was positively correlated with a higher stage (p=0.001), higher grade (p=0.001), histological type II disease (p=0.0003) and metastases (p=0.02). The implemented hierarchical clustering revealed that cluster 2 was characterised by high copy numbers of the studied genes. Cluster 2 was associated with shorter overall survival (p=0.05). The platform was found to be a fast and simple method for direct analysis of the genes involved in uterine carcinogenesis, making it feasible for EC biology characterisation.

Thyroid transcription factor-1 (TTF-1) is a marker of tumors of pulmonary and thyroid origin, and its expression practically excludes diagnosis of Merkel cell carcinoma (MCC). However, TTF-1 expression in combined MCC was recently reported. PAX5 is a marker of B-cell origin that is also expressed in most classical MCC cases; however, its expression was not described in combined MCC. The authors decided to evaluate the expression of both these markers in a group of 5 combined MCCs (2 with invasive squamous cell carcinoma, 2 with squamous cell carcinoma in situ, and 1 with basal cell carcinoma). Expression of TTF-1 was found in 4 of 5 cases; in 3 cases, the marker was shown in the MCC component (weakly in 2 cases and strongly in 1 case), whereas the non-MCC component presented TTF-1 expression in 2 cases. A weak-to-moderate immunoreactivity for PAX5 was identified in all cases of the MCC component but in none of the non-MCC component. The results show that the expression of TTF-1 is a frequent finding in combined MCC and can be present in the neuroendocrine component, which differs from the conventional MCC. In contrast, PAX5 expression pattern is similar to that of the classical MCC.

Background Endometrial cancer (EC) is a hormone-related disease, showing highly diverse features of ER/PR/HER2 status-based molecular subtypes. Long noncoding RNA (lncRNA) HOX antisense intergenic RNA (HOTAIR) has recently emerged as a key molecule in many cancers, triggering epithelial-mesenchymal transition (EMT)–mediated cancer stem cell (CSC) formation, but little is known about its significance in EC. Thus, we aimed to investigate the clinical significance of HOTAIR itself in different molecular subtypes of EC and possible links between HOTAIR, EMT and CSC-related markers. Methods The study group included 156 consecutive, stage I-IV EC patients treated between 2000 and 2010. ER, PR and HER2 protein expression were examined by immunohistochemistry (IHC) on tissue microarrays. RT-qPCR was used to analyze the expression levels of HOTAIR, EMT-related genes – SNAIL and SLUG – and the CSCs marker CD133. Results Molecular subtypes, defined as ER/PR+HER2+, ER/PR+HER2-, ER-PR-HER2+ and ER-PR-HER2-, occurred in 40.2%, 52.3%, 4.7% and 1.9% of cases, respectively. The expression of HOTAIR did not differ between the subtypes, but high HOTAIR expression correlated with shorter overall survival (p = 0.04) in the entire group. The expression levels of HOTAIR, SNAIL, SLUG and CD133 were similar in defined EC molecular subtypes. Conclusions Our data do not confirm the role of HOTAIR in EMT-mediated CSC formation in EC. Neither does the diversity of EC molecular subtypes influence these processes. But HOTAIR expression could serve as an independent prognostic factor in EC. The clinical importance of the above discoveries requires further studies.

ETV6 gene abnormalities are well described in tumor pathology. Many fusion partners of ETV6 have been reported in a variety of epithelial and hematological malignancies. In salivary gland tumor pathology, however, the ETV6-NTRK3 translocation is specific for mammary analogue secretory carcinoma (MASC), and has not been documented in any other salivary tumor type. The present study comprised a clinical and molecular analysis of 25 cases morphologically and immunohistochemically typical of MASC. They all also displayed the ETV6 rearrangement as visualized by fluorescent in situ hybridization but lacked the classical ETV6-NTRK3 fusion transcript by standard reverse-transcriptase-polymerase chain reaction. In 4 cases, the classical fusion transcript was found by more sensitive, nested reverse-transcription-polymerase chain reaction. Five other cases harbored atypical fusion transcripts as detected by both standard and nested reverse-transcription-polymerase chain reaction. In addition, fluorescent in situ hybridization with an NTRK3 break-apart probe was also performed; rearrangement of NTRK3 gene was detected in 16 of 25 cases. In 3 other cases, the tissue was not analyzable, and in 2 further cases analysis could not be performed because of a lack of appropriate tissue material. Finally, in the 4 remaining cases whose profile was NTRK3 split-negative and ETV6 split-positive, unknown (non-NTRK) genes appeared to fuse with ETV6 (ETV6-X fusion). In looking for possible fusion partners, analysis of rearrangement of other kinase genes known to fuse with ETV6 was also performed, but without positive results. Although numbers were small, correlating the clinico-pathologic features of the 4 ETV6-X fusion tumors and 5 MASC cases with atypical fusion transcripts raises the possibility of that they may behave more aggressively.

The aim the study was to compare two groups of endometrial cancer patients (below and above 45 years of age) in the aspect of clinicopathological and molecular data.The study encompassed 456 primary tumour samples retrospectively collected from a cohort of endometrial cancer patients, primarily treated by surgery Molecular analysis covered: copy number variations of 10 genes (TOP2A, ERBB1, ERBB2, ERBB3, ERBB4, MYC, CCND1, ESR1, PIK3CA, RAD21) analyzed by quantitative PCR; mRNA expression of 6 genes (SCGB2A2, RAD27, RUNX1, SNAI1, SNAI2, PROM1) analyzed with the use of reverse transcription quantitative PCR; protein expression analysis of 8 markers (PGR, ESR1; ERBB1, ERBB2, ERBB3, ERBB4, TOP2A, pAKT1) performed with the use of immunohistochemistry.The younger group of patients was characterized by less frequent hypertension (p0.00007), less frequent myometrial infiltration (p=0.002) and longer overall survival (p=0.003). Apart from RAD21 gene aberrations, which were more frequent in younger patients (p=0.02), the study revealed no statistically significant differences between the groups.The study showed no molecular differences in the profile of younger and older endometrial cancer patients. Data on both the prognostic and predictive significance of RAD21 in endometrial cancer are still insufficient. The clinical profile of younger patients with endometrial carcinoma was slightly better when compared to elderly patients. Younger patients were characterized by longer overall survival.

Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) are presumed to be key conditions for malignancy. Data concerning their role in endometrial cancer (EC) are scarce. We aimed to investigate the possible link between EMT and CSCs markers in EC samples.The study encompassed 156 primary tumour samples. Using RT-qPCR, we analyzed the expression of EMT-related genes, SNAIL and SLUG, and the CSCs marker CD133.SNAIL and SLUG correlated with each other (R=0.33; p=0.00003). All the studied genes were expressed in both normal and malignant endometrial tissue. Decreased SNAIL expression was found to correlate with post-menopausal status (p=0.002). Decreased SLUG expression was associated with shorter overall survival (p=0.01).SLUG expression could serve as a prognostic factor in EC. No correlation between the expression of EMT and CSCs markers was found, suggesting there to be no association between the EMT and CSC phenotype in endometrial cancer.

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumour that harbours the recurrent ETV6-NTRK3 translocation. This is the first series of MASC cases identified in the historic cohort of carcinomas of salivary glands with clinical/pathological correlation and follow-up data. We reviewed 183 primary carcinomas of major and minor salivary glands resected at the Medical University of Gdansk, Poland, between 1992 and 2012. Based on morphology and immunohistochemistry, cases suspicious for MASC were selected, and the diagnosis was confirmed by fluorescence in situ hybridization (FISH) for ETV6 rearrangement and by RT-PCR for the ETV6-NTRK3 fusion transcript. Seven carcinomas met the criteria of MASC, as they exhibited a typical appearance with solid/microcystic and papillary architecture and intraluminal secretions, and cells completely devoid of basophilic cytoplasmic zymogen granules indicative of true acinar differentiation. The only paediatric case was an unencapsulated tumour composed of macrocystic structures covered by a mostly single but, focally, double layer of cells with apocrine morphology. In all cases, the neoplastic cells revealed immunoreactivity for S100, mammaglobin, cytokeratin CK7, CK8, STAT5a and vimentin. FISH for ETV6 gene rearrangement was positive in six out of seven cases, and RT-PCR was positive in three cases. MASC is a new entity of malignant epithelial salivary gland tumours not included in the 2005 WHO Classification of Head and Neck Tumours. There is a growing body of evidence that it is not as rare as was assumed, as is also indicated by our series (3.8 %). In most cases, MASC shares some microscopic features with AciCC, adenocarcinoma/cystadenocarcinoma NOS and low-grade MEC. In rare cases, MASC with high-grade transformation may mimic the morphological appearances of high-grade salivary gland malignancies, such as salivary duct carcinoma.

Reassessment of histological specimens of salivary gland carcinomas is associated with a change of primary diagnosis in a significant number of patients. The authors evaluated the relation between reclassification/verification of histological diagnosis and the clinical course of parotid gland carcinomas. Histological and immunohistochemical examinations of 111 specimens of parotid gland carcinomas operated on during the years 1992-2010 were revised and in some cases supplemented with cytogenetic tests (FISH), to verify the diagnosis and potentially reclassify the tumours. Analysis of the clinical documentation and follow-up data of patients whose diagnosis was changed was then carried out. The prognostic factors taken into account in the evaluation of the clinical course included the T and N stage, the tumour grade and the extent of resection. The primary diagnosis was changed on review in 28 patients (25.2 %). In 16 patients, the change involved a different histological type of cancer. In six cases, what was thought to be a primary salivary gland cancer was reclassified as a secondary tumour. In four other cases, the change was made from a malignant to a benign tumour and in one case to a non-neoplastic lesion (necrotizing sialometaplasia). Additionally, in two patients with carcinoma ex pleomorphic adenoma, the malignant component was found to be of in situ type. A potentially atypical clinical course was observed in 4 out of 28 patients whose diagnosis was changed. In the case of 2 patients, the course of disease was more aggressive (dissemination, death) than predicted and less aggressive in rest of the patients. Histological reclassification/verification of parotid gland carcinomas can explain the cause of an atypical clinical course in some patients and sometimes enables doctors to implement a change in therapy.