Mammalian mastermind like 2 11q21 gene rearrangement in bronchopulmonary mucoepidermoid carcinoma

Primary hepatobiliary mucoepidermoid carcinoma: a case report and review of literature

Hepatobiliary mucoepidermoid carcinoma is a rare malignant tumor comprising mucous, intermediate, and epidermoid cells. Herein, we presented a case of primary liver mucoepidermoid carcinoma preoperatively misdiagnosed as conventional intrahepatic cholangiocarcinoma. A 67-year-old male was admitted to our hospital. Preoperative laboratory tests showed increased aspartate transaminase, alanine transaminase, and carbohydrate antigen 19-9. Abdominal Computer Tomography revealed a 4.8 × 4.9 cm liver mass in segment VI. A preliminary diagnosis of intrahepatic cholangiocarcinoma was made, with undergoing partial hepatectomy. However, on histopathology, the tumor comprised a mixture of epidermoid, mucous, and intermediate cells with diffuse infiltrating at the tumor margin. On special stains, mucous and intermedia cells were positive for mucicarmine and Alcian blue, whereas epidermoid cells were positive for Keratin 5/6 and p63. Intermediate cells are also positive for p63. All tumor cells were positive for Keratin 7. The Ki-67 index was 35%. The final diagnosis was primary hepatic mucoepidermoid carcinoma. Although rare, hepatic mucoepidermoid carcinoma should be considered in the intrahepatic cholangiocarcinoma differential diagnosis. We reviewed previous studies and found that hepatobiliary mucoepidermoid carcinoma is more likely to originate from the biliary tract adjacent to the tumor.

Current diagnosis and treatment of salivary gland-type tumors of the lung

Salivary gland-type tumors of the lung are thought to originate from the submucosal exocrine glands of the large airways. Due to their rare occurrence, reports of their study are limited to small-scale or case reports. Therefore, daily clinical practices often require a search for previous reports. In the last 20 years, several genetic rearrangements have been identified, such as MYB::NF1B rearrangements in adenoid cystic carcinoma, CRTC1::MAML2 rearrangements in mucoepidermoid carcinoma, EWSR1::ATF1 rearrangements in hyalinizing clear cell carcinoma and rearrangements of the EWSR1 locus or FUS (TLS) locus in myoepithelioma and myoepithelial carcinoma. These molecular alterations have been useful in diagnosing these tumors, although they have not yet been linked to molecularly targeted therapies. The morphologic, immunophenotypic, and molecular characteristics of these tumors are similar to those of their counterparts of extrapulmonary origin, so clinical and radiologic differential diagnosis is required to distinguish between primary and metastatic disease of other primary sites. However, these molecular alterations can be useful in differentiating them from other primary lung cancer histologic types. The management of these tumors requires broad knowledge of the latest diagnostics, surgery, radiotherapy, bronchoscopic interventions, chemotherapy, immunotherapy as well as therapeutic agents in development, including molecularly targeted agents. This review provides a comprehensive overview of the current diagnosis and treatment of pulmonary salivary gland tumors, with a focus on adenoid cystic carcinoma and mucoepidermoid carcinoma, which are the two most common subtypes.

Clinical presentation and treatment of four children with pulmonary mucoepidermoid carcinoma

Primary lung cancer in childhood is extremely rare, with an incidence rate of less than 2/100,0000, and pulmonary mucoepidermoid carcinoma (PMEC), is even rarer. Their symptoms are usually not specific, and there are no guidelines for their management, which makes their clinical management a challenge for pediatricians. The purpose of this report is to discuss the clinical presentation, positive signs, examinations, pathological characteristics, surgical modalities, chemotherapy regimens, and prognosis in children. The clinical data of four patients diagnosed with PMEC at the Children's Hospital of Chongqing Medical University from June 2021 to November 2022 were retrospectively analyzed, and their clinical features, treatment, and prognosis were summarized. Among them, two were male and two were female; their ages ranged from 3 years and 10 months to 10 years and 11 months, and all were staged according to tumor node metastasis classification (TNM). Immunohistochemical tests were performed in all children, among which four cases were positive for cytokeratin (CK), two cases were positive for CK7, four cases were positive for p63, about 5-10% of tumor cells were positive for Ki67. Among the four children, three had surgery alone and one had surgery + chemotherapy. All four children are presently living, with no evidence of tumor recurrence or metastasis. PMEC in children is very rare, and its age of onset and symptoms are not specific, and there is no obvious correlation with gender. Its diagnosis mainly relies on pathomorphological diagnosis, and immunohistochemical detection has no specific performance. The prognosis of children with PMEC is related to the clinical stage and whether surgery is performed. Whether further chemotherapy or radiotherapy is needed for patients who cannot undergo surgical resection and for those who have a combination of distant metastases requires further clinical studies.

Recent developments in the pathology of primary pulmonary salivary gland-type tumours

Primary pulmonary salivary gland-type tumours are rare neoplasms that are thought to arise from seromucinous glands that are located in the submucosa of large airways. These neoplasms have clinical and pathologic features that are distinct from other pulmonary neoplasms. The majority of primary pulmonary salivary gland-type tumours are malignant, with the most common entities being mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. Less commonly seen are myoepithelial carcinoma, hyalinizing clear cell carcinoma, acinic cell carcinoma, secretory carcinoma, salivary duct carcinoma, intraductal carcinoma, and polymorphous adenocarcinoma. Benign salivary gland-type tumours of the lung include pleomorphic adenoma and sialadenoma papilliferum. Morphologic, immunophenotypic, and molecular features of these neoplasms are largely similar to salivary gland tumours elsewhere, and therefore the exclusion of metastatic disease requires clinical and radiologic correlation. However, the differential diagnostic considerations are different in the lung. The distinction of salivary gland-type tumours from their histologic mimics is important for both prognostication and treatment decisions. Overall, salivary gland type-tumours tend to have a more favourable outcome than other pulmonary carcinomas, although high-grade variants exist for many of these tumour types. Recent advances in our understanding of the spectrum of salivary gland-type tumours reported in the lung and their diversity of molecular and immunohistochemical features have helped to refine the classification of these tumours and have highlighted a few differences between salivary gland-type tumours of the lung and those primary to other sites.

Mucoepidermoid carcinoma of the lung with hemoptysis as initial symptom: A case report

BACKGROUND

Mucoepidermoid carcinoma of the lung is a rare malignant tumor, accounting for 0.1%-0.2% of all lung malignancies. It is a primary salivary gland tumor of the lung. Surgical resection is the primary treatment for pulmonary mucoepidermoid carcinoma, for which there has been no standardized treatment strategy. This article reports a case of a young woman with pulmonary mucoepidermoid carcinoma with hemoptysis as the first symptom.

CASE SUMMARY

A 24-year-old female patient presented with "4 d of hemoptysis" as the chief complaint. She had no special history and denied any smoking or drinking history. Physical examination revealed that the vital signs were stable and scattered small wet rales were heard in the left lung. After admission, the lung tumor markers were checked, and no abnormalities were found. After completing the bronchoscopy, a spherical lesion was observed at the main bronchus 1.5 cm away from the protubercle, with obvious pulsation and little blood seepage on the surface, and histopathological biopsy results showed acute and chronic inflammation. She was transferred to the Department of Thoracic Surgery for surgical treatment on the 16th day after admission. After exclusion of surgical conjunctures, the patient underwent resection of the tumor in the left main bronchus with single-pore video-assisted thoracic surgery on the 19th day after admission. The postoperative histopathological biopsy results showed mucoepidermoid carcinoma of the lung. The patient and her family refused to complete genetic testing and she was discharged from the hospital on the 8th day after surgery. During the follow-up period, the patient experienced shortness of breath after feeling active and had no special discomfort.

CONCLUSION

We have documented a case of moderately differentiated mucoepidermoid lung cancer with hemoptysis as the first symptom to improve clinicians' understanding of the disease and provide a new dimension of thinking for its future diagnosis and treatment.

Pulmonary mucoepidermoid carcinoma in children: two case reports and a review of the literature

Pulmonary mucoepidermoid carcinoma (PMEC) is a rare tumor, particularly in children, and its clinical manifestations vary. When the tumor is small, it may be asymptomatic; however, with larger tumors, patients may present with symptoms such as recurring pneumonia, atelectasis, persistent cough, chest pain, and even hemoptysis. PMEC appears as an exophytic intrabronchial mass. This study aims to report on the clinical manifestations, imaging findings, treatment approaches, and prognosis of two children diagnosed with PMEC at our hospital between January 2018 and December 2022. The age of onset for both children was 9 years, and the masses were located in the right upper lobe bronchi. Following surgical treatment, both patients showed a good prognosis. In addition, we conducted a comprehensive review of the relevant literature to enhance the overall understanding of PMEC.

A case of lung carcinoma with a unique biphasic feature: Implications for histogenesis of "fake mucoepidermoid carcinoma" developing in the peripheral lung

We present a case of lung carcinoma with a unique biphasic feature. The patient was a 67-year-old male smoker with idiopathic pulmonary fibrosis (IPF). A subpleural tumor in the left lower lobe, embedded in fibrotic tissue, was resected. Histologically, the tumor consisted of major and minor components of mucoepidermoid carcinoma (MEC) and surrounding conventional lepidic adenocarcinoma, respectively. Both components had the same TP53 somatic mutation (p.V157F) but not Mastermind-like 2 (MAML2) gene rearrangement. The two components may have developed from an identical origin. The tumor could be trans-differentiating from lepidic adenocarcinoma to MEC, possibly promoted by IPF-induced tissue damage. The final diagnosis was "adenosquamous carcinoma with mucoepidermoid-like features (that may originate from lepidic adenocarcinoma)." This case has implications for the potential histogenesis of peripheral lung MEC. Over time, the MEC would expand and outgrow the lepidic adenocarcinoma, making it impossible to distinguish between fake and true MEC. The present case suggests that peripheral MEC could differ from proximal MEC in its histogenesis and molecular genetics. Thus, careful examination is necessary to diagnose peripheral lung MEC, particularly in patients with interstitial lung diseases.

Mucoepidermoid Carcinoma of the Lung Harboring MET Exon 14 Skipping Mutation Treated With Tepotinib: A Case Report

A case of pulmonary mucoepidermoid cancer harboring MET exon 14 skipping mutation and responding to tepotinib.

Pulmonary Salivary Gland Tumor, Mucoepidermoid Carcinoma: A Literature Review

Pulmonary mucoepidermoid carcinoma (PMEC) is the most common malignant salivary gland tumor in the lungs and accounts for 0.1-0.2% of all lung malignancies in adults. It has no specific epidemiological or clinical characteristics. Correct diagnosis requires the combined examinations of images, laboratories, pathology, and immunohistochemistry (IHC) as well as molecular characteristics. PMEC tumors are characterized by squamous, intermediate, and mucus-secreting cells. Currently, histological appearance, mitotic frequency, cellular atypia, and necrocytosis allow the classification of PMEC into low grade or high grade. Molecular changes are crucial to pathological diagnosis. The driver of PMEC seems to be the fusion protein MECT1-MAML2 that is generated from a genetic mutation in t (11; 19) (q21; p13), while other gene mutations are also reported. However, no treatment of PMEC exists so far; surgical excision is still the primary treatment, while the efficacies of chemotherapy or radiotherapy are undefined. Tyrosine kinase inhibitor (TKI) therapy and immunotherapy showed to have significant therapeutic effects but require more investigation and better understanding. This review focuses on the clinical characteristics, imaging and pathologic features, immunohistochemical examination, mutation analysis, differential diagnosis, prognosis, and treatment of PMEC.

Mucoepidermoid carcinoma (MEC) and adenosquamous carcinoma (ASC), the same or different entities?

Mucoepidermoid carcinoma (MEC) and adenosquamous carcinoma (ASC) have overlapping histopathological appearances and sites of occurrence, which may cause diagnostic difficulty impacting subsequent treatment. We conducted a systematic review of the scientific literature to determine whether molecular alterations were sufficiently different in MEC and ASC to aid in classifying the two entities. We searched Medline, Embase and Web of Science for studies reporting molecular determinations of ASC and/or MEC and screened retrieved records for eligibility. Two independent researchers reviewed included studies, assessed methodological quality and extracted data. Of 8623 identified records, 128 articles were included for analysis: 5 which compared the two tumors in the same investigation using the same methods and 123 which examined the tumors separately. All articles, except one were case series of moderate to poor methodological quality. The 5 publications examining both tumors showed that 52/88 (59%) MEC and 0% of 110 ASC had rearrangement of the MAML2 gene as detected by FISH and/or RT-PCR, but did not investigate other genes. In the entire series MEC had MAML2 gene rearrangement in 1337/2009 (66.6%) of tumors studied. The articles examining tumors separately found that MEC had mutations in EGFR (11/329 cases, 3.3%), KRAS (11/266, 4.1%) and ERBB2 (9/126, 7.1%) compared with ASC that had mutations in EGFR (660/1705, 38.7%), KRAS (143/625, 22.9%) and ERBB2 (6/196, 3.1%). The highest level of recurrent mutations was in pancreatic ASC where (108/126, 85.7%) reported mutations in KRAS. The EGFR mutations in ASC were similar in number and kind to those in lung adenocarcinoma. By standards of systematic review methodology and despite the large number of retrieved studies, we did not find adequate evidence for a distinctive molecular profile of either MEC or ASC that could definitively aid in its classification, especially in histologically difficult cases that are negative for MAML2 rearrangement. The case series included in this review indicate the relevance of MAML2 rearrangement to support the diagnosis of MEC, findings that should be confirmed by additional research with adequate study design.

A Young Child With Recurrent Pneumonia and Hemoptysis During the COVID-19 Pandemic

In July 2020, a previously healthy 6-year-old boy was evaluated in a pulmonary clinic in New York after two episodes of pneumonia in the previous 3 months. For each episode, the patient presented with cough, fever, and hemoptysis, all of which resolved with antibiotic therapy and supportive care. The patient never experienced dyspnea during these episodes of pneumonia. He was asymptomatic at the current visit. The patient had no history of travel, sick contacts, asthma, or bleeding disorders.

Diagnostic Value of MAML2 Rearrangements in Mucoepidermoid Carcinoma

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

Salivary Gland-type Tumors of the Lung

CONTEXT.—

Salivary gland-type tumors (SGTs) of the lung represent a distinct group of lung neoplasms. Pulmonary SGTs often pose diagnostic challenges, especially in small biopsy and cytology samples because of limited sample volume and overlapping morphology among pulmonary SGTs, metastatic SGTs of head and neck origin, and other lung tumors.

OBJECTIVE.—

To identify the clinical characteristics, histomorphology, immunophenotypic features, and molecular alterations that are crucial for the diagnosis and differential diagnosis of pulmonary SGTs, especially in small biopsy and cytology specimens.

DATA SOURCES.—

Literature review and authors' personal practice experience.

CONCLUSIONS.—

An accurate diagnosis of pulmonary SGTs can be achieved by careful evaluation of clinical findings and histomorphology in conjunction with immunohistochemical studies and molecular analysis.

Mutational landscape of primary pulmonary salivary gland-type tumors through targeted next-generation sequencing

OBJECTIVES

Primary pulmonary salivary gland-type tumors (PSGTs) mainly comprise of mucoepidermoid carcinoma (MEC) and adenoid cystic carcinoma (ACC), which are rare and molecularly poorly understood. This study aimed to profile the molecular alterations of PSGTs via targeted next-generation sequencing (NGS).

MATERIAL AND METHODS

Immunohistochemistry was used to screen PSGTs in 32 patients and MAML2 and MYB rearrangements were detected using fluorescence in situ hybridization. 1021-Genepanel of targeted NGS was conducted to profile genomic mutations in all the PSGT patients.

RESULTS

Among the 32 patients, 25 had MEC and 7 had ACC. MAML2 and MYB rearrangements were detected in 80.0% (20/25) of the MEC and 71.4% (5/7) of the ACC patients. Among the MEC patients, 10 (40.0%) had ≥1 mutation, and 6 of them had 11 isolated mutations with abundance >5%, namely NFE2L2, MYOD1, INPP4B, CCND2, SNTG1, HSPD1, TGFBR1, RBM10, NOTCH4, ASXL1, and PTPRD mutations. The remaining 4 patients had 9 mutations with abundance <5%, namely KMT2A, PDCD11, FLT1, BRCA2, APC, SLX4, FOXP1, FGFR1, and HRAS mutations. All the ACC patients had mutations, which were enriched in 5 pathways including the PI3K and NOTCH pathways, chromatin and cytoskeleton remodeling, and DNA damage. These results explain PSGTs harbor distinct driver features of MAML2 or MYB rearrangement, accompanied with wide mutational diversity with very low rate of somatic mutation. Several important pathways, including the NOTCH and PI3K pathways, and chromatin remodeling could be targeted to improve the survival in patients with ACC.

Updates in the molecular pathology of non-small cell lung cancer

An understanding of the molecular pathology of non-small cell lung cancer (NSCLC) is important for pathologists as molecular characterization is now required for treatment decisions in advanced stage disease. While assessment for EGFR mutations, ALK and ROS1 fusions, and in some countries BRAF mutations, is now standard practice, other oncogenic mutations are also emerging that may impact routine clinical practice including alterations involving KRAS, NTRK, RET, MET and HER2. In addition, molecular pathology alterations of NSCLC are associated with responses to immune checkpoint therapy and are being increasingly investigated. Finally, specific molecular pathological alterations define some rarer subtypes of NSCLC such as salivary gland tumours, NUT carcinoma and SMARCA4-deficient undifferentiated tumour, and an understanding of the molecular pathology is important for their accurate diagnosis. In this review, the molecular pathology of NSCLC is discussed with a focus on clinically relevant molecular alterations.

Whole-exome sequencing reveals the etiology of the rare primary hepatic mucoepidermoid carcinoma

Background

Primary hepatic mucoepidermoid carcinoma (HMEC) is extremely rare and the molecular etiology is still unknown. The CRTC1-MAML2 fusion gene was previously detected in a primary HMEC, which is often associated with MEC of salivary gland in the literature.

Methods

A 64-year-old male was diagnosed with HMEC based on malignant squamous cells and mucus-secreting cells in immunohistochemical examination. Fluorescence in situ hybridization (FISH) was used to detect the CRTC1-MAML2 fusion gene in HMEC. Whole-exome sequencing and Sanger sequencing were used to reveal the molecular characteristics of HMEC and analysis was performed with public data. Pedigree investigation was performed to identify susceptibility genes.

Results

Hematoxylin–eosin staining and immunohistochemistry revealed that the tumor cells were composed of malignant epidermoid malignant cells and mucous cells, indicating a diagnosis of HMEC. The CRTC1-MAML2 fusion gene was not detected in the primary HMEC, and somatic mutations in GNAS, KMT2C and ELF3 genes were identified by sequencing. Analyses of public data revealed somatic GNAS alterations in 2.1% hepatobiliary tumors and relation with parasite infection. Heterozygous germline mutations of FANCA, FANCI, FANCJ/BRIP1 and FAN1 genes were also identified. Pedigree investigation verified that mutation of Fanconi’s anemia susceptibility genes were present in the pedigree.

Conclusions

Here we provide the first evidence of the molecular etiology of a rare HMEC associated with germline Fanconi’s anemia gene mutations and somatic GNAS R201H mutation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01086-3.

Recent updates in salivary gland tumors of the lung

Salivary gland tumors are uncommon primary lesions in the lung. Their morphologic, immunophenotypic, and molecular characteristics resemble those of their counterparts in the head and neck or elsewhere. Most common primary pulmonary salivary gland tumors include mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. The study of these neoplasms is hampered by their paucity. Therefore, studies are in general small or restricted to individual cases. Despite this challenge recent advances have been made specifically at the molecular level. Molecular alterations such as MAML2 rearrangements in mucoepidermoid carcinoma, MYB rearrangements in adenoid cystic carcinomas, and EWSR1 rearrangements in hyalinizing clear cell carcinomas and myoepithelial tumors have been identified. These molecular alterations might be helpful in the distinction of these salivary gland tumors from other neoplasms in the lung. However, the distinction from metastatic disease remains challenging. Awareness of these tumors and knowledge of available ancillary studies to confirm the diagnosis is important to avoid misdiagnosis which might lead to differences in treatment, management, and prognosis. Further studies are needed to identify biomarkers to better predict patient's outcome and for individual management and treatment of patients.

Primary pulmonary mucoepidermoid carcinoma: Cyto-histologic correlation and review of the literature

Preoperative fine needle aspiration diagnosis and cyto-histologic correlation of primary pulmonary mucoepidermoid carcinoma have rarely been described in detail in the literature. A 26-year old male presented at our institution with cough, bloody sputum, and a 4.3 cm left lower lobe lung mass. He was accurately diagnosed with pulmonary mucoepidermoid carcinoma on preoperative aspiration cytology. The patient subsequently proceeded to left lower lobectomy, confirming the diagnosis. In this article, we present a detailed report of primary pulmonary mucoepidermoid carcinoma describing the cytologic and histologic morphologic features, its differential diagnosis with review of the literature.

Conjunctival Adenosquamous Carcinoma Lacks MAML2 Translocation: A Variant of Squamous Cell Carcinoma With Mucoepidermoid Differentiation and Aggressive Behavior?

Conjunctival adenosquamous carcinoma, also known as mucoepidermoid carcinoma (MEC), is a rare tumor that preferentially affects the perilimbal area of the conjunctiva with aggressive local invasion. Consisting of infiltrative proliferation of squamous cells and mucous cells, its morphologic features are reminiscent of the salivary gland-type MEC except for the absence of intermediate cells and frequent keratin production. We reported 2 cases of conjunctival adenosquamous carcinoma and, for the first time, studied the MAML2 translocation status of this rare entity. The 2 patients were women, aged 45 and 42 years, presenting with an erythematous lesion in the left lower palpebral conjunctiva and a pigmented nodule over the left nasal conjunctiva, respectively. One tumor recurred 6 months after the initial biopsy. Excision with lid reconstruction and postoperative radiotherapy was performed for margin involvement and perineural invasion. This patient was disease free at 3-year follow-up. The other patient was lost to follow-up after tumor excision. Fluorescence in situ hybridization and reverse transcription polymerase chain reaction failed to demonstrate MAML2 translocation and CRCT1-MAML2 transcripts in both tumors. The absence of this characteristic translocation and reappraisal of the cellular composition, morphologic features, and precursor lesion suggest that conjunctival MEC may represent a variant of conjunctival squamous cell carcinoma but not related to the salivary gland-type MEC.

Primary Lung Tumors in Children: Radiologic-Pathologic Correlation From the Radiologic Pathology Archives

Primary lung tumors in children are rare, with a narrow range of diagnostic considerations. However, the overlapping imaging appearances of these tumors necessitate attention to key discriminating imaging and pathologic features. In the neonate and infant, the important considerations include pleuropulmonary blastoma (PPB), infantile fibrosarcoma, and fetal lung interstitial tumor. Among these tumors, imaging findings such as air-filled cysts in type 1 PPB and homogeneously low attenuation of fetal lung interstitial tumors are relatively specific. Key pathologic and genetic discriminators among this group of tumors include the DICER1 germline mutation found in PPB and the t(12,15)(p13;q25) translocation and ETV6-NTRK3 fusion gene seen in infantile fibrosarcoma. Primary lung tumors in older children include inflammatory myofibroblastic tumors (IMTs), carcinoid salivary gland-type tumors of the lung, recurrent respiratory papillomatosis, and other rare entities. IMT, a spindle-cell proliferation with inflammatory elements, is the most common lung tumor in children. Anaplastic lymphoma kinase, a receptor-type protein tyrosine kinase, is present in 50% of these tumors, and this finding may support an imaging diagnosis of IMT. Carcinoid tumors account for a substantial portion of childhood lung tumors, and their characteristic avid enhancement on images corresponds to the compressed fibrovascular stroma histologically. Furthermore, novel imaging agents used with somatostatin receptor analogs have an emerging role in the evaluation of carcinoid tumors. Although less common than mucoepidermoid carcinoma, adenoid cystic carcinoma tends to recur given the perineural spread seen histologically. Integrating radiologic and pathologic knowledge is critical to accurate diagnosis, treatment planning, and surveillance of primary lung tumors in children.

"Pancreatic Mucoepidermoid Carcinoma" Is not a Pancreatic Counterpart of CRTC1/3-MAML2 Fusion Gene-related Mucoepidermoid Carcinoma of the Salivary Gland, and May More Appropriately be Termed Pancreatic Adenosquamous Carcinoma With Mucoepidermoid Carcinoma-like Features

"Mucoepidermoid carcinoma (MEC)" has been accepted as a synonym for pancreatic adenosquamous carcinoma (ASC). Pancreatic ASC can show salivary gland-type MEC-like morphology. CRTC1/3-MAML2 fusion gene is a characteristic molecular feature of MEC of the salivary gland. We conducted this study to clarify whether the pancreatic ASC with salivary gland-type MEC-like morphology (Pan-MEC) is a pancreatic counterpart of salivary gland-type MEC (Sal-MEC). We retrospectively analyzed 37 pancreatic ASCs including 16 Pan-MECs and 21 tumors without MEC-like features (ASC-NOS [not otherwise specified]), and we investigated (1) clinicopathologic features, (2) the presence of CRTC1/3-MAML2 fusion gene by reverse transcription polymerase chain reaction, (3) the presence of rearrangement of MAML2 gene by fluorescence in situ hybridization, and (4) mucin core proteins by immunohistochemistry. We also compared 16 Pan-MECs with 20 Sal-MECs by immunohistochemistry for mucin core protein. There were no significant differences of any clinicopathologic characteristics and survival analysis between the Pan-MECs and ASCs-NOS. Of note, the pancreatic ASCs (including Pan-MEC and ASC-NOS) were significantly more aggressive than conventional pancreatic ductal adenocarcinoma. In addition, all Pan-MECs were histologically high-grade. CRTC1/3-MAML2 fusion gene and MAML2 gene rearrangement were not detected in any ASCs including Pan-MECs. There were significant differences of MUC5AC and MUC6 between the Pan-MECs and Sal-MECs, but no significant differences of mucin core protein between the Pan-MECs and pancreatic ASCs-NOS. Pan-MEC is histologically and biologically high-grade and unrelated to CRTC1/3-MAML2 fusion gene, unlike Sal-MEC which is related to CRTC1/3-MAML2 fusion gene. Pan-MEC is not a pancreatic counterpart of CRTC1/3-MAML2 fusion gene-related Sal-MEC.

[Immunophenotyping of lung tumors : An update]

The WHO Classification of Lung Tumors (2015) established the use of immunohistochemical stainings for resection specimens, however, detailed recommendations had been missing. Now, an international expert panel has summarized key questions for daily routine practice and provided recommendations to assist the community in the appropriate use of immunohistochemistry in this context. This article provides an overview of the most important aspects.

Uncommon Types of Lung Carcinoma With Mixed Histology: Sarcomatoid Carcinoma, Adenosquamous Carcinoma, and Mucoepidermoid Carcinoma

CONTEXT

- Lung tumors are histologically heterogeneous, but classification of lung carcinoma has prognostic impact and increasingly, specific molecular correlates.

OBJECTIVE

- To update the gross, microscopic, and molecular pathology of unusual lung carcinomas to assure accurate classification. In entities with mixed histology, the recognition of specific features or rare patterns is critical to diagnosis. These diagnoses can identify tumors with aggressive clinical behavior, and diagnostic pitfalls can therefore result in underdiagnosis of these already rare entities. Incorrect classification of more indolent tumors into the more aggressive categories can also occur. In the area of molecular pathology, these unusual tumors have a specific spectrum of molecular alterations.

DATA SOURCES

- PubMed searches for lung and sarcomatoid carcinoma, pleomorphic carcinoma, blastoma, carcinosarcoma, and adenosquamous and mucoepidermoid carcinoma were undertaken and this information was integrated with clinical experience of the author.

CONCLUSIONS

- These uncommon carcinomas have specific clinicopathologic features, and attention to their gross and microscopic pathology leads to classification with important associated molecular findings.

Molecular and Morphological Profiling of Lung Cancer: A Foundation for "Next-Generation" Pathologists and Oncologists

The pathological diagnosis of lung cancer has largely been based on the morphological features observed microscopically. Recent innovations in molecular and genetic technology enable us to compare conventional histological classifications, protein expression status, and gene abnormalities. The introduction of The Cancer Genome Atlas (TCGA) project along with the widespread use of the next-generation sequencer (NGS) have facilitated access to enormous data regarding the molecular profiles of lung cancer. The World Health Organization classification of lung cancer, which was revised in 2015, is based on this progress in molecular pathology; moreover, immunohistochemistry has come to play a larger role in diagnosis. In this article, we focused on genetic and epigenetic abnormalities in non-small cell carcinoma (adenocarcinoma and squamous cell carcinoma), neuroendocrine tumor (including carcinoids, small cell carcinoma, and large cell neuroendocrine carcinoma), and carcinoma with rare histological subtypes. In addition, we summarize the therapeutic targeted reagents that are currently available and undergoing clinical trials. A good understanding of the morphological and molecular profiles will be necessary in routine practice when the NGS platform is widely used.

Best Practices Recommendations for Diagnostic Immunohistochemistry in Lung Cancer

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.

The Role of Molecular Testing in the Differential Diagnosis of Salivary Gland Carcinomas

Salivary gland neoplasms are a morphologically heterogenous group of lesions that are often diagnostically challenging. In recent years, considerable progress in salivary gland taxonomy has been reached by the discovery of tumor type-specific fusion oncogenes generated by chromosome translocations. This review describes the clinicopathologic features of a selected group of salivary gland carcinomas with a focus on their distinctive genomic characteristics. Mammary analog secretory carcinoma is a recently described entity characterized by a t(12;15)(p13;q25) translocation resulting in an ETV6-NTRK3 fusion. Hyalinizing clear cell carcinoma is a low-grade tumor with infrequent nodal and distant metastasis, recently shown to harbor an EWSR1-ATF1 gene fusion. The CRTC1-MAML2 fusion gene resulting from a t(11;19)(q21;p13) translocation, is now known to be a feature of both low-grade and high-grade mucoepidermoid carcinomas associated with improved survival. A t(6;9)(q22-23;p23-34) translocation resulting in a MYB-NFIB gene fusion has been identified in the majority of adenoid cystic carcinomas. Polymorphous (low-grade) adenocarcinoma and cribriform adenocarcinoma of (minor) salivary gland origin are related entities with partly differing clinicopathologic and genomic profiles; they are the subject of an ongoing taxonomic debate. Polymorphous (low-grade) adenocarcinomas are characterized by hot spot point E710D mutations in the PRKD1 gene, whereas cribriform adenocarcinoma of (minor) salivary glands origin are characterized by translocations involving the PRKD1-3 genes. Salivary duct carcinoma (SDC) is a high-grade adenocarcinoma with morphologic and molecular features akin to invasive ductal carcinoma of the breast, including HER2 gene amplification, mutations of TP53, PIK3CA, and HRAS and loss or mutation of PTEN. Notably, a recurrent NCOA4-RET fusion has also been found in SDC. A subset of SDC with apocrine morphology is associated with overexpression of androgen receptors. As these genetic aberrations are recurrent they serve as powerful diagnostic tools in salivary gland tumor diagnosis, and therefore also in refinement of salivary gland cancer classification. Moreover, they are promising as prognostic biomarkers and targets of therapy.

CRTC1-MAML2 fusion-induced lncRNA LINC00473 expression maintains the growth and survival of human mucoepidermoid carcinoma cells

Mucoepidermoid carcinoma (MEC) arises in many glandular tissues and contributes to the most common malignant salivary gland cancers. MEC is specifically associated with a unique t(11;19) translocation and the resulting CRTC1-MAML2 fusion is a major oncogenic driver for MEC initiation and maintenance. However, the molecular basis underlying the CRTC1-MAML2 oncogenic functions remain very limited. Through gene expression profiling analysis, we observed that LINC00473, a long noncoding RNA (lncRNA), was the top down-regulated target in CRTC1-MAML2-depleted human MEC cells. LncRNAs belong to a new class of non-coding RNAs with emerging roles in tumorigenesis and progression, but remain poorly characterized. In this study, we investigated the role of LINC00473 in mediating CRTC1-MAML2 oncogenic activity in human MEC. We found that LINC00473 transcription was significantly induced in human CRTC1-MAML2-positive MEC cell lines and primary MEC tumors, and was tightly correlated with the CRTC1-MAML2 RNA level. LINC00473 induction was dependent on the ability of CRTC1-MAML2 to activate CREB-mediated transcription. Depletion of LINC00473 significantly reduced the proliferation and survival of human MEC cells in vitro and blocked the in vivo tumor growth in a human MEC xenograft model. RNA in situ hybridization analysis demonstrated a predominantly nuclear localization pattern for LINC00473 in human MEC cells. Furthermore, gene expression profiling revealed that LINC00473 depletion resulted in differential expression of genes important in cancer cell growth and survival. LINC00473 likely regulates gene expression in part through its ability to bind to a cAMP signaling pathway component NONO, enhancing the ability of CRTC1-MAML2 to activate CREB-mediated transcription. Our overall results demonstrate that LINC00473 is a downstream target and an important mediator of the CRTC1-MAML2 oncoprotein. Therefore, LINC00473 acts as a promising biomarker and therapeutic target for human CRTC1-MAML2-positive MECs.

Clinicopathological characteristics and molecular analysis of primary pulmonary mucoepidermoid carcinoma: Case report and literature review

Primary pulmonary mucoepidermoid carcinoma (PMEC) is extremely rare. Herein, we report a case of a 71‐year‐old male patient with high‐grade PMEC involving the right upper lobe that was successfully resected via lobectomy. As a result of invasion into the pleural and paratracheal lymph nodes, four cycles of adjuvant chemotherapy with paclitaxel and carboplatin were administered. There were no signs of relapse during 10 months of follow‐up. Furthermore, we reviewed the literature and summarized the surgical approaches, prognostic factors, and underlying genetic mechanisms of PMEC, which will benefit clinical treatment.

The Molecular Pathology of Lung Cancer

Advances in lung cancer genomics have revolutionized the diagnosis and treatment of this heterogeneous and clinically significant group of tumors. This article provides a broad overview of the most clinically relevant oncogenic alterations in common and rare lung tumors, with an emphasis on the pathologic correlates of the major oncogenic drivers, including EGFR, KRAS, ALK, and MET. Illustrations emphasize the morphologic diversity of lung adenocarcinoma, including genotype-phenotype correlations of genomic evolution in tumorigenesis. Molecular diagnostic approaches, including PCR-based testing, massively parallel sequencing, fluorescence in situ hybridization, and immunohistochemistry are reviewed.

Surgical outcomes of pulmonary mucoepidermoid carcinoma: A review of 41 cases

INTRODUCTION

Pulmonary mucoepidermoid carcinoma is a rare cancer that occurs primarily in younger patients. The prognostic factors of pulmonary mucoepidermoid carcinoma are largely undetermined, especially in elderly patients. The aim of this study was to examine the clinical characteristics and prognostic factors influencing survival after surgical resection in patients with pulmonary mucoepidermoid carcinoma and also analyze the clinical manifestations and prognostic factors in elderly patients.

MATERIALS AND METHODS

The pathological records of 41 pulmonary mucoepidermoid carcinoma patients (mean age, 61.4 years) who underwent surgical resection at our hospital between January 1991 and July 2015 were retrospectively reviewed. Subjects >65 years of age (n = 22) were considered elderly.

RESULTS

The median follow-up duration was 42.9 (interquartile range, 15.0-120.8) months. Sixteen patients (39.0%) experienced tumor relapse, including 13 patients (81.3%) within 2 years. The 5-year disease-free survival rate was 57.9%. Tumor grade did not influence disease-free survival (P = 0.286). In the multivariate analysis, age, tumor size, pathological T3-4 status, and pathological N2 status were independent predictors of disease-free survival. The 5-year overall survival rate was 57.0%. Tumor grade also did not influence overall survival (P = 0.170). Age, tumor size, pathological T status, and pathological N2 status were independent predictors of overall survival. In elderly patients, the 5-year disease-free survival and overall survival rates were 41.4% and 41.5%, respectively. Pathological T status was the only independent predictor of both disease-free survival and overall survival in elderly patients.

CONCLUSIONS

Prognostic factors identified for pulmonary mucoepidermoid carcinoma in this study differ from those of previous studies. Principally, tumor grade did not influence either disease-free survival or overall survival. Age, tumor size, and pathological factors were independent predictors of disease-free survival and overall survival. In elderly patients, pathological T status was the only independent predictor of disease-free survival and overall survival.

New Developments in Salivary Gland Pathology: Clinically Useful Ancillary Testing and New Potentially Targetable Molecular Alterations

Accurate diagnosis of salivary gland tumors can be challenging because of the many diagnostic entities, the sometimes extensive morphologic overlap, and the rarity of most tumor types. Ancillary testing is beginning to ameliorate some of these challenges through access to newer immunohistochemical stains and fluorescence in situ hybridization probes, which can limit differential diagnostic considerations in some cases. These ancillary testing strategies are especially useful in small biopsy samples, including aspiration cytology. Molecular techniques are also expanding our understanding of salivary gland tumor pathology and are helping to identify potential targets that may improve treatment for some of these tumors. Here, we summarize the clinical use of new immunohistochemical markers in our practice and review the current understanding of chromosomal rearrangements in salivary gland tumor pathology, emphasizing the prospects for exploiting molecular alterations in salivary gland tumors for diagnosis and targeted therapy. We find that immunohistochemistry and fluorescence in situ hybridization are powerful tools toward the diagnosis of salivary gland tumors, especially when used in a systematic manner based on morphologic differential-diagnostic considerations. As new targeted therapies emerge, it will become increasingly vital to incorporate appropriate molecular testing into the pathologic evaluation of salivary gland cancers.

The 2015 World Health Organization Classification of Tumors of the Thymus: Continuity and Changes

This overview of the 4th edition of the World Health Organization (WHO) Classification of thymic tumors has two aims. First, to comprehensively list the established and new tumor entities and variants that are described in the new WHO Classification of thymic epithelial tumors, germ cell tumors, lymphomas, dendritic cell and myeloid neoplasms, and soft-tissue tumors of the thymus and mediastinum; second, to highlight major differences in the new WHO Classification that result from the progress that has been made since the 3rd edition in 2004 at immunohistochemical, genetic and conceptual levels. Refined diagnostic criteria for type A, AB, B1-B3 thymomas and thymic squamous cell carcinoma are given, and it is hoped that these criteria will improve the reproducibility of the classification and its clinical relevance. The clinical perspective of the classification has been strengthened by involving experts from radiology, thoracic surgery, and oncology; by incorporating state-of-the-art positron emission tomography/computed tomography images; and by depicting prototypic cytological specimens. This makes the thymus section of the new WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart a valuable tool for pathologists, cytologists, and clinicians alike. The impact of the new WHO Classification on therapeutic decisions is exemplified in this overview for thymic epithelial tumors and mediastinal lymphomas, and future perspectives and challenges are discussed.

Primary Pulmonary Salivary Gland-type Tumors: A Review and Update

Pulmonary salivary gland-type tumors (SGT) comprise a very small proportion of primary lung neoplasms. The most common tumors among this group are mucoepidermoid carcinoma and adenoid cystic carcinoma. Contrary to the head and neck region, benign SGT such as pleomorphic adenomas are exceedingly rare in the pulmonary system. More recently, 2 additional SGT, namely hyalinizing clear cell carcinoma and salivary duct-like carcinoma were recognized as primary lung tumors expanding the spectrum of SGT that have been described to originate in the tracheobronchial system. Primary pulmonary SGT must be clinically excluded from metastatic salivary gland neoplasms as their morphology is indistinguishable from that of their salivary gland counterparts. Little is known about the clinical behavior and best treatment approach for these unusual tumors. In this review, we provide a comprehensive summary of primary pulmonary SGT with particular emphasis on morphologic characteristics and latest developments in terms of immunohistochemical and molecular techniques.

Landscape of gene fusions in epithelial cancers: seq and ye shall find

Enabled by high-throughput sequencing approaches, epithelial cancers across a range of tissue types are seen to harbor gene fusions as integral to their landscape of somatic aberrations. Although many gene fusions are found at high frequency in several rare solid cancers, apart from fusions involving the ETS family of transcription factors which have been seen in approximately 50% of prostate cancers, several other common solid cancers have been shown to harbor recurrent gene fusions at low frequencies. On the other hand, many gene fusions involving oncogenes, such as those encoding ALK, RAF or FGFR kinase families, have been detected across multiple different epithelial carcinomas. Tumor-specific gene fusions can serve as diagnostic biomarkers or help define molecular subtypes of tumors; for example, gene fusions involving oncogenes such as ERG, ETV1, TFE3, NUT, POU5F1, NFIB, PLAG1, and PAX8 are diagnostically useful. Tumors with fusions involving therapeutically targetable genes such as ALK, RET, BRAF, RAF1, FGFR1-4, and NOTCH1-3 have immediate implications for precision medicine across tissue types. Thus, ongoing cancer genomic and transcriptomic analyses for clinical sequencing need to delineate the landscape of gene fusions. Prioritization of potential oncogenic "drivers" from "passenger" fusions, and functional characterization of potentially actionable gene fusions across diverse tissue types, will help translate these findings into clinical applications. Here, we review recent advances in gene fusion discovery and the prospects for medicine.

Primary Pulmonary Mucoepidermoid Carcinoma: Histopathological and Moleculargenetic Studies of 26 Cases

Introduction

Pulmonary mucoepidermoid carcinoma (PMEC) is an uncommon neoplasm of the lung and the main salivary gland-type lung carcinoma. The aims of this study were to review the clinicopathological and immunohistochemical features of PMEC and characterize the genetic events in PMEC.

Methods

We reviewed the pathology cases in our hospital and found 34 initially diagnosed PMEC cases, 26 of which were confirmed as PMEC after excluding 8 cases of MEC-like pulmonary carcinoma. The clinicopathological characteristics of the 26 PMEC cases and the 8 cases of MEC-like pulmonary carcinoma were retrospectively reviewed. MAML2 rearrangement was detected by fluorescence In Situ Hybridization (FISH). Immunostains of ALK, calponin, collagen IV, CK7, EGFR, HER2, Ki-67, Muc5Ac, p63, p40, and TTF-1 were performed. DNA was extracted from 23 cases of PMEC. Mutation profiling of the EGFR, KRAS, BRAF, ALK, PIK3CA, PDGFRA, and DDR2 genes were carried out using next-generation sequencing (NGS), Sanger sequencing, and quantitative polymerase chain reaction (QPCR) in 9 successfully amplified cases.

Results

Twenty-six cases of PMEC (18 low-grade, 8 high-grade) included 13 men and 13 women aged 12–79 years. Twenty-two cases had a central/endobronchial growth pattern, and 4 cases had a peribronchial growth pattern. Immunohistochemically, CK7, Muc5Ac, p40, and p63 were positive in all cases (26/26);EGFR was positive in 11 cases (11/26); TTF-1, Calponin, HER2 and ALK were negative in all cases (0/26). MAML2 rearrangement was identified in 12 of 18 PMEC cases. No mutations were detected in any of the 7 genes in the 9 cases that qualified for mutation analysis. Twenty-three PMEC patients had follow-up information with a median interval of 32.6 months. Both the 5- and 10-year overall survival rates (OS) were 72.1%, and a high-grade tumor was an adverse prognostic factor in PMEC. There were 8 cases of MEC-like pulmonary carcinoma aged 36–78 years: 2 cases were located in the bronchus, and 6 cases were located in the lung. p63 and TTF-1 were positive in all cases (8/8), p40 was positive in 5 cases (5/8), and ALK was positive in 5 cases (5/8). No cases of MAML2 rearrangement were detected, but there were 5 cases of ALK rearrangement.

Conclusions

PMEC is a primary malignant pulmonary tumor with a relatively good prognosis that is historically characterized by the presence of mucous cells and a lack of keratinization. There are distinct differences between PMEC and MEC-like pulmonary carcinoma in tumor location preference, immunophenotype, and molecular genetics, and the differential diagnosis is critical due to the therapeutic and prognostic considerations.

Primary intraosseous mucoepidermoid carcinoma of the jaw: Reappraisal of The MD Anderson Cancer Center experience

BACKGROUND

Mucoepidermoid carcinoma arises from major or minor salivary glands, making up 10% of salivary gland tumors. Intraosseous mucoepidermoid carcinomas are rare, and make up only 2% to 3% of all mucoepidermoid carcinomas. The t(11;19) and its CRTC1-MAML2 fusion gene transcript have been identified in mucoepidermoid carcinoma and are associated with a subset of mucoepidermoid carcinomas. The extent to which the transcript influences disease features and patient survival is unclear.

METHODS

We conducted a retrospective analysis of records for clinical features, surgical interventions, and prognoses. Reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) used to assess the t(11;19) fusion gene in intraosseous mucoepidermoid carcinoma.

RESULTS

Twenty-five patients with intraosseous mucoepidermoid carcinoma treated between 1998 and 2013 were identified. The t(11;19) fusion gene transcript CRTC1-MAML2 manifested in 9 intraosseous mucoepidermoid carcinomas, whereas is was not detected in another 9 intraosseous carcinomas. Although the incidence of this fusion in mucoepidermoid carcinoma varies, it is generally accepted that more than 50% of this entity manifest the CRTC1-MAML2.

CONCLUSION

Intraosseous mucoepidermoid carcinoma diagnosis should be based on clinical and pathologic manifestations and complete resection is the first choice for patient treatment. The need for neck dissection and adjuvant treatment are debatable. Radiotherapy may improve prognosis and may be recommended in the postoperative period. Primary intraosseous mucoepidermoid carcinoma can manifest the fusion transcript in a subset of tumors. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1312-E1317, 2016.

Efficacy of Bronchoscopic Therapies for Bronchial Mucoepidermoid Carcinoma in Children: Results from Six Patients

Aims and Background

Bronchial mucoepidermoid carcinoma is a rare disease in children, and lobectomy is traditionally considered as a first-line treatment. As the tumor is characterized by intraluminal growth, low malignancy and superficial infiltration of bronchial walls, bronchoscopic interventional therapy may provide an alternative treatment with favorable results. The aim of the study was to evaluate the efficacy and safety of bronchoscopic therapies for bronchial mucoepidermoid carcinoma in children.

Methods and Study design

Clinical manifestations, multiple bronchoscopic interventions and outcomes in 6 children with bronchial mucoepidermoid carcinoma were retrospectively analyzed.

Results

The median age was 8.7 years (range 4 to 12 years). All the tumors were located in the lobar bronchus and were detected by computerized tomography. Diagnoses of low-grade mucoepidermoid carcinoma were made based on biopsies obtained via bronchoscopy. Five tumors were classified as intraluminal type and successfully eradicated by carbon dioxide cryotherapy and argon plasma coagulation under bronchoscopy. The other tumor in patient 3 was classified as the mixture type and could not be removed by a bronchoscopic, so left upper lobectomy was performed. For each patient, interventional procedures were conducted on the average for 6 times. No recurrence was detected by bronchoscopic inspections or computed tomography scans during follow-ups for 16-72 months.

Conclusions

Multiple bronchoscopic procedures, as alternative treatments, are effective in removing bronchial mucoepidermoid carcinoma mucoepidermoid carcinoma in children without any major complications.

Mixed mucoepidermoid carcinoma and adenocarcinoma of the lung: Two cases with unusual histologic features

We herein report two cases of non-small cell lung cancer with unusual histologic patterns, comprising mixed mucoepidermoid carcinoma and adenocarcinoma. Both cases presented identical genetic mutations in each histologic component of the tumor; specifically, one case possessed an ALK-rearrangement and the other case presented a deletion in exon 19 of the EGFR gene. The two current cases, as well as an additional case that we previously reported, were all identified as being a specific type of mixed lung cancer with driver mutations typically encountered in conventional lung adenocarcinomas. Our findings support the supposition that different histological components in mixed-histology lung cancer are clonally related. Accordingly, extensive tissue sampling is necessary to avoid overlooking minor adenocarcinomatous components, as patients with mixed lung cancer could potentially benefit from treatment with tyrosine kinase inhibitors.

Thymic Mucoepidermoid Carcinoma

Thymic mucoepidermoid carcinoma (TMEC) is a vanishingly rare entity that usually presents as low to intermediate grade MEC and carries a better prognosis when compared with other poorly differentiated thymic carcinomas. The recently described fusions, t(11;19)(q21;p13) CREB (cAMP response element-binding protein)-regulated transcription coactivator 1 and MAML2, mastermind-like gene 2 (CRTC1-MAML2) and t(11:15)(q21;q26) CRTC3-MAML2 characterize a considerable proportion of MEC examples arising from a variety of anatomical sites. Recent data point out that the aberrant proteins produced by this fusion drive oncogenesis by disrupting the cAMP/CREB and NOTCH1 pathways. To date, only 2 TMEC cases have been reported to have MAML2 rearrangements, a feature that was found to be absent in TMEC mimics. These findings led the authors to recommend this test as a diagnostic tool in the differential diagnosis for thymic carcinoma. Herein, we present a case of TMEC arising in a 58-year-old woman, which was predominantly cystic with intracystic papillary formations composed of a mixture of mucinous cells and intermediate/epidermoid eosinophilic cells. This case was negative for CTCR1-MAML2 and CTCR3-MAML2 fusion transcripts by reverse transcriptase polymerase chain reaction and lacked a MAML2 rearrangement by fluorescence in situ hybridization. We report a CTCR1/3-MAML2 fusion and MAML2 rearrangement–negative TMEC, indicating that a different molecular pathway must be involved in the generation of these tumors. The possibility of fusion-negative TMEC should be taken into consideration in the differential diagnosis of a thymic carcinoma.

Histopathologic, immunophenotypic and cytogenetic features of pulmonary mucoepidermoid carcinoma

Pulmonary mucoepidermoid carcinoma is an uncommon but distinctive manifestation of mucoepidermoid carcinoma. Pulmonary mucoepidermoid carcinoma occurs in adults and children and can cause diagnostic problems, especially in small biopsies. Few studies have characterized the histologic and immunophenotypic features of pulmonary mucoepidermoid carcinoma. t(11;19)(q21;p13) is considered disease-defining for mucoepidermoid carcinoma; its significance in pulmonary mucoepidermoid carcinoma warrants further study. Forty three pulmonary mucoepidermoid carcinomas were re-reviewed and graded according to the Brandwein grading system for mucoepidermoid carcinoma. Four cases were excluded because of a split opinion between pathology report and re-review. These cases were negative for MAML2 rearrangement by FISH. TTF-1, napsin A, p40 and p63 immunostains were scored: 0 (negative), 1 (1-25% tumor cells), 2 (26-50%), 3 (51-75%) or 4 (>75%). FISH to detect MAML2 rearrangement used a MAML2-11q21 break-apart probe. Thirty nine pulmonary mucoepidermoid carcinoma (4 low, 30 intermediate, 5 high grade) contained mucous, epidermoid and intermediate cells and lacked keratinization and in situ carcinoma of the overlying epithelium. All cases with available gross description (n=22) had a central/endo- or peribronchial location. All 25 cases tested for immunohistochemistry were positive (scores 1-4) for p63; 23 also expressed p40. In six cases, the p63 score was higher than p40. TTF-1 and napsin were uniformly negative in all 25 cases. MAML2 rearrangement was identified by FISH in each of the 24 cases tested (3 low, 19 intermediate, 2 high grade). Clinical history was available in 29 patients (15 men) (median age, 48 years) with follow-up in 24 (median, 8.4 years). Five patients died of unrelated causes; one developed metastatic pulmonary mucoepidermoid carcinoma. In conclusion, features helpful in distinguishing pulmonary mucoepidermoid carcinoma from other lung cancers include its central/endo- or peribronchial location together with the presence of mucous cells, p63 expression, lack of keratinization and MAML2 rearrangement. TTF-1 and napsin are typically not expressed.

Mucoepidermoid carcinoma of lung masquerading as urothelial carcinoma of bladder

BACKGROUND

Mucoepidermoid carcinoma (MEC) of the lung is a rare subtype of non-small cell lung cancer. There is no consensus regarding optimal management for this disease.

CASE REPORT

We present a case of MEC of the lung in a 75 year-old female with a history of superficial urothelial carcinoma of the bladder. The patient was found to have an asymptomatic lung mass. Initial biopsy suggested metastatic recurrence of urothelial carcinoma and therefore, cisplatin and gemcitabine chemotherapy was administered prior to surgical resection. Pathological analysis of the resected specimen confirmed a diagnosis of stage IIIA MEC with focal high-grade features including transitional cell-like areas. Adjuvant radiotherapy was administered due to a positive microscopic resection margin. No chemotherapy was given due to lack of supporting data. The patient developed widespread metastatic disease 3 months following completion of radiotherapy and died 1 month later.

CONCLUSION

This case demonstrates the possibility of dual pathology in cases where metastatic disease is suspected. The use of small tissue samples may complicate diagnosis due to the heterogeneity of malignant tumours.

MAML2 rearrangement in primary pulmonary mucoepidermoid carcinoma and the correlation with FLT1 expression

Introduction

Primary pulmonary mucoepidermoid carcinoma (PMEC) is an uncommon neoplasm with remarkable resemblance to mucoepidermoid carcinoma of the salivary glands. The latter has been shown to harbor t(11,19) resulting in MECT1-MAML2 fusion, which may be of diagnostic and prognostic values. However, the importance of such feature in PMEC has not been well studied.

Methods

We detected MAML2 rearrangement using fluorescence in situ hybridization (FISH) in tissue samples from 42 cases of PMEC and 40 of adenosquamous carcinoma (ASC), and the expression of potential downstream targets of MECT1-MAML2, including HES1, FLT1 and NR4A2 with immunohistochemistry (IHC). The findings were then examined regarding the clinicopathological parameters and patient outcomes.

Results

FISH analysis revealed MAML2 rearrangement in 50% of the PMEC cases, and such property was prominent in considerable younger patients (33 versus 60 years; p = 0.001) and restricted to cases of low and intermediate grades. IHC analysis showed that FLT1 and HES1 were expressed at lower level in MAML2 rearranged group than MAML2 non-rearranged group (p<0.001 and p = 0.023, respectively). Survival analysis showed significant correlation between MAML2 rearrangement and overall survival (p = 0.023) or disease-free survival (p = 0.027) as well as correlation between FLT1 and overall survival (p = 0.009).

Conclusions

MAML2 rearrangement appears frequent in PMEC and specific with this tumor. Both the presence of MAML2 rearrangement and absence of FLT1 tend to confer a favorable clinical outcome. These findings suggest that molecular detection of MAML2 rearrangement combined with FLT1 may be of important clinical value for PMEC.

Glandular odontogenic cysts (GOCs) lack MAML2 rearrangements: a finding to discredit the putative nature of GOC as a precursor to central mucoepidermoid carcinoma

Glandular odontogenic cyst (GOC) is a cyst of the gnathic bones that is characterized by squamous and glandular differentiation. The histopathologic features of GOC overlap considerably with central mucoepidermoid carcinoma (MEC), suggesting that GOC could be a precursor lesion to, or even a low-grade form of, central MEC. Differentiating the two lesions may be difficult or impossible on a limited biopsy. MAML2 rearrangements have been recently found to be specific for MEC, even those arising in the jaws. An analysis of MAML2 in GOCs could help clarify its relationship with central MEC. Tissue blocks from 21 GOCs and 5 central MECs were retrieved from the surgical pathology archives of The Johns Hopkins Hospital. Each MEC exhibited solid areas and clear-cut stromal invasion. In addition, 4 of the MECs demonstrated cystic areas that were histologically similar to GOC. Break-apart fluorescence in situ hybridization for MAML2 was performed. For the MECs, analysis was performed on both the solid components and the cystic areas that resembled GOC. MAML2 rearrangements were identified in all 5 of the MECs, but in none of the 21 GOCs (100 vs. 0 %; p < 0.0001, Fisher's Exact). In the MECs, the rearrangement was present in both the solid and GOC-like cystic areas. While central MECs consistently harbor the MAML2 rearrangement, even in low-grade cystic areas that resemble a pre-existing GOC, true GOCs do not. Accordingly, GOC does not appear to represent an early or low-grade form of central MEC, but rather an unrelated lesion. The high sensitivity and specificity of MAML2 rearrangement for MECs points to its utility as a diagnostic adjunct in separating mucinous cystic lesions of the gnathic bones.

Pulmonary adenosquamous carcinoma with mucoepidermoid carcinoma-like component with characteristic p63 staining pattern: either a novel subtype originating from bronchial epithelium or variant mucoepidermoid carcinoma

BACKGROUND

Our previous study found unique adenosquamous carcinomas (ADSQs) containing a mucoepidermoid carcinoma (MEC)-like component and a characteristic p63 staining pattern. This study focused on these unique ADSQs.

METHODS

Thirty ADSQ cases were studied histologically and by immunohistochemistry for TTF-1 and p63. Of these 30 ADSQs, eight were selected as unique ADSQs. The clinicopathological characteristics of these ADSQs were further studied, and the gene rearrangement of mammalian mastermind-like 2 (MAML2) was investigated by fluorescence in situ hybridization (FISH) for differentiation from pulmonary MEC.

RESULTS

The clinicopathological characteristics between the eight ADSQs and the other ADSQ cases showed no statistically significant differences, except for serum CEA level. Histologically, the eight ADSQs contained varying degrees of the MEC-like component, which consisted of solid nests with mucin-filled cysts or a cribriform-like structure. Immunohistochemically, p63-positive nuclei characteristically encircled the tumor nests, although TTF-1 was completely negative. All unique ADSQs not only had a variable degree of squamous cell carcinoma component in addition to the MEC-like component, but also contained a small tubular adenocarcinoma component in three tumors. FISH analysis revealed no MAML2 gene rearrangement in the eight ADSQs.

CONCLUSIONS

Of the 30 ADSQs investigated in this study, eight contained a MEC-like component with a characteristic p63 basilar staining pattern similar to that of bronchial basal cells. These unique ADSQs shared clinical characteristics with ordinary ADSQs, but clinicopathologically differed from pulmonary ordinary MEC. Therefore, these unique ADSQs may be either a novel ADSQ subtype originating from bronchial epithelium or variant-type MEC.

Unusual combined thymic mucoepidermoid carcinoma and thymoma: a case report and review of literature

BACKGROUND

In rare condition, combined thymic epithelial tumors showing either type A or type B thymomas areas combined with thymic carcinoma components may occur in thymus. Mucoepidermoid carcinoma (MEC) of the thymus is rare in thymic carcinoma, and so far there is no report to describe a combined epithelial tumor of thymus with MEC component. We report an unusual case of combined thymic MEC/type B2 thymoma in a middle-aged male occurring in a mass of anterior mediastinum.

CASE REPORT

A 51-year-old Chinese male patient presented with a 6-month history of right ptosis and progressive muscle weakness. Computed tomography (CT) examination revealed a solitary, well-circumscribed mass was in the anterior mediastinum with mild heterogeneous enhancement. Histologically, the mass contained two separated components and displayed typically histological features of low-grade MEC and type B2 thymoma, respectively. There was no gradual transition of these two components observed in mass, and no enlarged lymph node was found in the surrounding tissues. A diagnosis of combined thymic MEC/type B2 thymoma was made. The patient received thymectomy to resect the mass totally. After surgery, chemotherapy with regiments of cisplatin and mitomycin, and radiotherapy of the main tumor bed were performed on the patient. There was no evidence of tumor recurrence during the period of 12 months follow-up.

CONCLUSION

To our best knowledge, this is the first report of combined thymic epithelial tumor with MEC component. Although this tumor is rare, the diagnosis of a thymic MEC should be taken into consideration when a combined epithelial tumor is occasionally encountered in thymus.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9721397571157894.

Mucoepidermoid carcinoma of the lung: a case report and literature review

Introduction. Mucoepidermoid carcinoma (MEC) of the lung is a rare form of lung cancer that is classified into low grade and high grade based on histological features. Surgical resection is the primary treatment for low-grade MEC with excellent outcomes, while high-grade MEC is a more aggressive form of malignancy. Clinical Case. We report a case of a 46-year-old woman who presented with dyspnea on exertion. Imaging studies revealed a mass involving the right upper lobe bronchus. Bronchoscopy, surgical resection, and pathological examination revealed a low-grade MEC with tumor-free margins. No adjuvant treatment was given. Discussion. Primary pulmonary MEC is a rare type of lung cancer with only few reported cases. This patient illustrates a typical presentation for low-grade MEC wherein surgical resection is considered curative. In contrast, high-grade MEC is a more aggressive malignancy with a poorer outcome. The role of targeted therapy directed against EGFR or a novel CRTC1-MAML2 fusion protein expressed in some high-grade tumors is yet to be determined.

Analysis of MAML2 rearrangement in mucoepidermoid carcinoma of the thymus

Primary thymic mucoepidermoid carcinoma (TMEC) is rare. High-grade TMEC can be difficult to distinguish from poorly differentiated squamous cell carcinoma and adenosquamous carcinoma. A strong association between mucoepidermoid carcinoma (MEC) and t(11;19)(q21;p13) has been observed in other anatomical sites. Although this translocation is largely considered a disease-defining event for MEC, its incidence in TMEC has not been explored. In this study, we evaluate the value of identifying MAML2 rearrangement by fluorescence in situ hybridization (FISH) to distinguish TMEC from poorly differentiated squamous cell carcinoma and adenosquamous carcinoma. Cases of TMEC, moderate to poorly differentiated squamous cell carcinoma, and adenosquamous carcinoma were re-reviewed by 3 surgical pathologists and classified according to the current World Health Organization classification of thymic tumors (2004). Cases of TMEC were histologically graded using the Brandwein system. FISH was used to detect MAML2 rearrangements using a break-apart probe. FISH for MAML2 rearrangement was performed on cases of TMEC (n = 2), thymic squamous cell carcinoma (n = 5), and thymic adenosquamous carcinoma (n = 3). The 2 cases of TMEC showed MAML2 rearrangement. All other tested cases did not show rearrangement of MAML2. In conclusion, using FISH to identify MAML2 rearrangement is a valuable diagnostic tool in the evaluation of thymic malignancies, specifically, distinguishing TMEC from squamous cell carcinoma and adenosquamous carcinoma. These findings also suggest that TMEC has both histomorphologic and cytogenetic similarities to cases of MEC arising from other anatomical sites.