The landscape of salivary gland carcinomas is ever-changing, with a growing list of new tumors and newly elucidated variants of well-known tumor entities. The routine use of next-generation ...sequencing has been instrumental in identifying novel fusions and tumor entities, which has helped bring the classification to a more objective and evidenced-based model. However, morphology remains critical in assessing the validity of these novel molecular findings, and most importantly, in assessing which of these findings will have an impact on the prognosis and treatment decisions for patients. The recognition of microsecretory adenocarcinoma (MSA) as a distinct low-grade malignancy of salivary glands, underpinned by MEF2C::SS18 , and a single possibly related case of SS18::ZBTB7A , recently expanded this growing list of distinctive tumors. It was not until now, however, that the morphology of the latter case was known to be unique and reproducible. The authors have now seen 4 of these distinctive tumors that show a combination of distinctive oncocytic cells forming compact glandular growth as well as amphophilic cells forming tubular growth, and suggest the appellation "microcribriform adenocarcinoma" (MCA). So far, these tumors appear to preferentially occur in nonoral sites (2 parotid, 1 submandibular gland, and 1 bronchial seromucous glands). By immunohistochemistry, they express S100 and SOX-10 with focal outer myoepithelial cells marked by circumferential p63, p40, and smooth muscle actin staining around some of the nests and tubules. The tumors show infiltrative growth within a hyalinized and myxoid stroma. Cytologically, they appear generally low grade, similar to MSA. The morphologic and molecular uniformity of these 4 microcribriform adenocarcinoma cases warrants their recognition, and while related to MSA, they are sufficiently different to be classified as a distinct tumor. So far, in limited follow-up, these tumors appear to be relatively indolent.
Salivary gland adenocarcinoma not otherwise specified (NOS) is a heterogenous group, likely containing distinct tumors not yet characterized. A growing number of low to intermediate-grade salivary ...carcinomas are now known to harbor tumor-specific gene fusions. On occasion, identifying a novel fusion allows for recognition of a new salivary tumor type, in addition to representing a potential diagnostic tool. We sought to characterize a distinctive salivary gland adenocarcinoma that would previously have been regarded as adenocarcinoma NOS. On the basis of the recognition of 5 morphologically identical, distinct low-grade salivary adenocarcinomas, we used targeted RNA sequencing (RNA-Seq) to determine whether these could be differentiated from other fusion-associated salivary gland tumors. RNA-Seq was performed on all 5 low-intermediate grade adenocarcinomas NOS with near-identical histologic appearances, as well as 23 low-intermediate grade control adenocarcinoma NOS cases that did not resemble the index cases. All 5 index cases harbored a novel MEF2C-SS18 gene fusion, which was independently confirmed by reverse transcriptase-polymerase chain reaction. The MEF2C-SS18-positive cases arose in the oral cavity (4/5) and parotid gland (1/5) of 3 women and 2 men ranging from 21 to 80 years (mean: 46) and shared near-identical histologic features: intercalated duct-like cells with eosinophilic to clear cytoplasm and small, uniform oval nuclei, infiltrative microcysts and cords, abundant intraluminal secretions, and cellular fibromyxoid stroma. Mitotic rates were low; necrosis was absent. All MEF2C-SS18-positive tumors were positive for S100 and p63 and negative for p40, smooth muscle actin, calponin, and mammaglobin. One of the 23 control cases, a parotid tumor, was found to contain a SS18-ZBTB7A gene fusion; it demonstrated similar, but not identical histologic and immunophenotypic features compared with the MEF2C-SS18 cases. The remaining control cases were negative for SS18 and MEF2C rearrangements. A novel MEF2C-SS18 gene fusion and unique histologic and immunophenotypic features characterize a heretofore undefined low-grade salivary adenocarcinoma for which we propose the term "microsecretory adenocarcinoma." RNA-Seq helped establish this entity as a distinct tumor type, and identified one possibly related case with a different SS18-related fusion. The recognition of microsecretory adenocarcinoma and its separation from other adenocarcinomas NOS will facilitate a more complete understanding of the clinical and pathologic characteristics of this previously unrecognized neoplasm.
Adamantinoma-like Ewing sarcoma (ALES) is a rare tumor that demonstrates the EWSR1-FLI1 translocation characteristic of Ewing sarcoma despite overt epithelial differentiation including diffuse ...expression of cytokeratins and p40. Most cases of ALES described to date have occurred in the head and neck where they can mimic a wide range of small round blue cell tumors. Because distinguishing ALES from basaloid salivary gland carcinomas can be particularly difficult, we analyzed a series of 10 ALESs that occurred in the salivary glands with the aim of identifying features that allow for better recognition of this entity. The salivary ALESs included 8 parotid gland and 2 submandibular gland tumors in patients ranging from 32 to 77 years (mean: 52 y). Nine were initially misclassified as various epithelial neoplasms. Although these tumors displayed the basaloid cytology, rosette formation, infiltrative growth, and nuclear monotony characteristic of ALES, peripheral palisading and overt keratinization were relatively rare in this site. Salivary ALESs not only displayed positivity for AE1/AE3, p40, and CD99, but also demonstrated a higher proportion of synaptophysin reactivity than has been reported for nonsalivary ALESs. These morphologic and immunohistochemical findings make ALES susceptible to misclassification as various other tumors including basal cell adenocarcinoma, adenoid cystic carcinoma, squamous cell carcinoma, NUT carcinoma, large cell neuroendocrine carcinoma and myoepithelial carcinoma. Nevertheless, monotonous cytology despite highly infiltrative growth and concomitant positivity for p40 and synaptophysin can provide important clues for consideration of ALES, and identification of the defining EWSR1-FLI1 translocations can confirm the diagnosis.
Molecular analysis has reshaped the landscape of high grade sinonasal tumors by defining novel entities and identifying recurrent mutations in established tumor types. However, sinonasal ...teratocarcinosarcoma (TCS), a rare and aggressive tumor with intermixed teratomatous, carcinomatous, and sarcomatous elements, remains poorly understood. The multiphenotypic differentiation of TCS has engendered persistent controversy about its histogenesis and leads to diagnostic overlap with several other malignancies. In this study, we evaluated the molecular underpinnings of TCS to clarify its pathogenesis and diagnosis. We performed SMARCA4 immunohistochemistry (IHC) on 22 TCS and 153 other sinonasal tumors. We identified loss of SMARCA4 expression in 18 TCS (82%), including 15 (68%) with complete loss and 3 (14%) with partial loss. Although we also identified partial SMARCA4 loss in 1 of 8 SMARCB1-deficient sinonasal carcinomas (13%), SMARCA4 was intact in all other sinonasal carcinomas and neuroendocrine tumors. We then selected 3 TCS with complete SMARCA4 loss by IHC for a targeted next-generation sequencing panel that included 1425 cancer-related genes. We confirmed biallelic somatic inactivation of SMARCA4 without other known oncogenic mutations in these 3 cases. Overall, these findings suggest that SMARCA4 inactivation may be the dominant genetic event in TCS, expanding understanding of this gene's role in sinonasal tumorigenesis. They also raise the possibility that TCS is on a diagnostic spectrum with the newly described SMARCA4-deficient sinonasal carcinoma, blurring the lines between established and emerging sinonasal entities. In addition, SMARCA4 IHC may provide a useful adjunct for confirming a diagnosis of TCS in limited material.
A novel DEK-AFF2 fusion was recently reported in 4 nonkeratinizing squamous cell carcinomas of the sinonasal region and skull base, including 1 with exceptional response to immunotherapy, but it is ...not yet clear if this rearrangement defines a unique clinicopathologic category or represents a rare event. This study aims to characterize a larger cohort of carcinomas with DEK-AFF2 fusions to assess whether they truly constitute a distinctive entity. Among 27 sinonasal and skull base nonkeratinizing squamous cell carcinoma that were negative for human papillomavirus and Epstein-Barr virus, RNA sequencing identified DEK-AFF2 fusions in 13 cases (48%). Nine were centered in the nasal cavity, 2 in the middle ear/temporal bone, 1 in the nasopharynx, and 1 in the orbit. These tumors displayed recurrent histologic features including (1) complex endophytic and exophytic, frequently papilloma-like growth, (2) transitional epithelium with eosinophilic to amphophilic cytoplasm, (3) absent or minimal keratinization with occasional compact keratin pearls, (4) monotonous nuclei, and (5) prominent tumor-infiltrating neutrophils or stromal lymphocytes. This appearance not only overlaps with high-grade basaloid sinonasal carcinomas but also with benign papillomas and tumors reported as low-grade papillary Schneiderian carcinoma. However, DEK-AFF2 carcinomas showed frequent local recurrence, cervical lymph node metastases, and distant metastasis with 2 deaths from disease, confirming they are aggressive malignancies despite relatively bland histology. Overall, the distinctive molecular, histologic, and clinical features of DEK-AFF2 carcinomas suggest they represent a unique entity in the sinonasal region. This tumor merits increased pathologic recognition to better understand its prognostic and therapeutic implications.
Objectives/Hypothesis
To evaluate if a simple method for assessing tumor‐infiltrating lymphocytes (TIL) in primary tumor specimens improves the prognostic value of the American Joint Committee on ...Cancer, 8th Edition (AJCC8) cancer staging system in human papillomavirus–positive oropharyngeal squamous cell carcinoma (HPV‐OPC).
Study Design
Retrospective study.
Methods
In this study, TIL density was quantified on hematoxylin and eosin (H&E)–stained specimens from patients presenting to Johns Hopkins Hospital between 2009 and 2017 who underwent primary surgical therapy and had primary tumor specimens available for analysis. The prognostic effect of TIL density was evaluated by Kaplan‐Meier method and Cox proportional hazards models considering recurrence‐free survival (RFS) as the primary outcome.
Results
This study included 132 patients. Ninety‐five percent were classified by clinical criteria with AJCC8 early‐stage disease (stage I: 82%, stage II: 13%). After 84 months of follow‐up, 15 recurrences were observed. Among clinically early‐stage disease, TILhigh status was associated with improved RFS compared to TILlow (P = .002). Adjusted analysis showed TILhigh status was associated with 79% lower risk of recurrence than TILlow (adjusted hazard ratio aHR: 0.210, 95% confidence interval CI: 0.061‐0.723). In clinical stage I disease, TILhigh status was associated with improved RFS compared to TILlow in both univariate and multivariate analyses (hazard ratio: 0.235, P = .021; aHR: 0.218; 95% CI: 0.058‐0.822). TIL density similarly stratified risk in pathologically staged disease.
Conclusions
In patients with AJCC8 stage I disease, low TIL density was associated with diminished RFS. Our data suggest that assessing TIL density on H&E‐stained primary tumor specimens may enhance the prognostic resolution of the AJCC8 staging criteria for HPV‐OPC.
Level of Evidence
4 Laryngoscope, 130:930–938, 2020
Adenoid cystic carcinoma (AdCC) can demonstrate histologic and immunohistochemical (IHC) overlap with a wide range of salivary and nonsalivary tumors, especially in small biopsy specimens. While MYB ...fluorescence in situ hybridization (FISH) frequently is used to confirm the diagnosis of AdCC, the pathognomonic MYB-NFIB fusion is only present in 40% to 70% of cases. Likewise, although MYB RNA overexpression is seen in the vast majority of AdCC regardless of translocation status, MYB IHC has shown suboptimal specificity for this diagnosis. In this study, we sought to determine whether a novel chromogenic RNA in situ hybridization (ISH) platform could directly detect MYB RNA overexpression and offer a rapid diagnostic adjunct for AdCC. We performed MYB RNA ISH on 84 cases of AdCC as well as 128 other salivary tumors and 108 basaloid and sinonasal carcinomas that mimic AdCC. MYB RNA ISH was 92% sensitive for AdCC, including 97% of cases with MYB rearrangement and 83% without MYB rearrangement by FISH. It was also 89% specific for AdCC overall, with 95% specificity among other salivary tumors and 81% specificity in basaloid and sinonasal carcinomas. In contrast, MYB IHC was 94% sensitive but just 54% specific for AdCC. Overall, MYB RNA ISH provides superior sensitivity for the diagnosis of AdCC compared with MYB FISH and superior specificity compared with MYB IHC. This assay could provide a useful tool for rapidly confirming the diagnosis of AdCC in formalin-fixed, paraffin-embedded specimens.
Abstract Targeted therapies for pulmonary adenocarcinoma (ACA) necessitate specific subtyping and molecular testing of non-small cell lung carcinomas (NSCLC). However, endobronchial ultrasound-guided ...transbronchial needle aspiration (EBUS-TBNA) has decreased the tissue available for these assessments. While EBUS-TBNA specimens have previously been reported to, successfully subtype NSCLC, allow immunohistochemistry (IHC), and support molecular diagnostics, no studies have documented the extent to which all objectives are possible in a single sample. Of 107 consecutive EBUS-TBNA specimens that were eligible for molecular testing, 98.8% had enough tissue for IHC, 80.2 % received a definitive subtype, and 71.0% had both sufficient tissue to attempt molecular testing and technical success on multigene next generation sequencing (NGS) and ALK fluorescence in situ hybridization (FISH) assays. Both subtyping and molecular diagnostics were possible in 57.9% of patients. The mean number of immunostains performed did not differ between patients with or without successful molecular testing (4.4 vs. 4.6, p = 0.88). Only 40% of patients with insufficient tissue underwent repeat sampling. These findings indicate that a majority of EBUS-TBNA specimens provide sufficient tissue for subtyping pulmonary NSCLC, performing IHC, and completing multiple gene analyses. Although priorities must be assessed for each case individually, performance of IHC does not detract from completion of molecular diagnostics in general. Because most patients never undergo repeat sampling, the tissue yield of EBUS-TBNA should be improved to maximize evaluation for targeted therapies.
Highlights • HPV RISH detects transcriptionally active HPV in most p16+, HPV DISH-OPSCCs. • HPV RISH is highly sensitive and specific, easy to interpret, and readily automated. • By contrast to HPV ...RISH, the performance of second generation HPV DISH is poor. • HPV RISH should be considered as a first-line platform for HPV testing in OPSCCs.
Molecular analysis has allowed for refinement of salivary gland tumor classification and, in some cases, the recognition of entirely new tumor types. Microsecretory adenocarcinoma (MSA) is a salivary ...gland tumor described in 2019 characterized by microcystic growth, bland cytomorphology, luminal secretions, fibromyxoid stroma, and S100/p63 positivity with negative p40. Most important, MSA is defined by
MEF2C-SS18
fusion. While this fusion has, to this point, been detected by next-generation sequencing, this is a technique that is currently inaccessible in most diagnostic laboratories. On the other hand,
SS18
break-apart fluorescence in situ hybridization (FISH) is widely available and frequently used as an adjunct for diagnosing synovial sarcoma. It is not known if
SS18
break-apart FISH is positive in tumors with
MEF2C-SS18
, or if it is entirely specific for MSA. Break apart FISH for
SS18
was performed on 4 cases of MSA, as well as 8 tissue microarrays (TMAs) containing 423 various salivary gland carcinomas: 26 acinic cell carcinomas, 35 adenocarcinomas not otherwise specified, 96 adenoid cystic carcinomas, 3 basal cell adenocarcinomas, 20 epithelial–myoepithelial carcinomas, 15 hyalinizing clear cell carcinomas, 3 intraductal carcinomas, 12 myoepithelial carcinomas, 117 mucoepidermoid carcinomas, 30 polymorphous adenocarcinomas, 45 salivary duct carcinomas, 19 secretory carcinomas, and 2 undifferentiated carcinomas.
SS18
break-apart FISH was also performed on whole slides of 2 tumors from the TMAs. All MSA cases demonstrated classic split patterns on
SS18
break-apart FISH. On the TMAs, 374 cases were evaluable by FISH, and 372 cases were clearly negative for
SS18
rearrangement. Two cases, both mucoepidermoid carcinomas, had rare split signals below the positivity threshold of 12% on their TMA cores, so FISH was performed on whole sections. On the whole sections both tumors were unequivocally negative for
SS18
rearrangement. Taken together,
SS18
break-apart FISH was 100% sensitive and 100% specific for a diagnosis of MSA.
SS18
break-apart FISH, a diagnostic tool widely available in pathology laboratories, appears to be a highly accurate method for diagnosing MSA of salivary glands. Accordingly, this new tumor type may be molecularly confirmed without needing to resort to highly specialized techniques like next-generation sequencing.
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