Papillary-cystic neoplasms of the middle ear are distinct from endolymphatic sac tumours

ETV6::NTRK3-associated papillary adenocarcinoma: let us play it by ear

Ceruminous glands are modified apocrine glands, situated in the external auditory canal (EAC) that, together with sebaceous glands, produce cerumen. The neoplastic transformation of these structures is exceedingly rare. We encounter two cases of EAC adenocarcinoma with ETV6::NTRK3 fusion. Despite this genetic overlap, the morphology and immunophenotype delineate its clear separation from secretory carcinoma. These cases demonstrate novel primary EAC adenocarcinoma with papillary morphology, which expands the ever-increasing list of ETV6::NTRK3-positive malignancies and which we would like to term ETV6::NTRK3-translocation associated papillary adenocarcinoma. We also advocate the use of molecular techniques in rare tumors of uncertain type or differentiation, to increase understanding and possibilities of reproducible classification of these rare neoplasms. Pathologists and oncologists should recognize this entity, which leads to a direct approach for detecting NTRK fusion for appropriate treatment.

Detection of salivary gland and sinonasal fusions by a next-generation sequencing based, ligation-dependent, multiplex RT-PCR assay

AIMS

The discovery of tumour type-specific gene fusion oncogenes in benign and malignant salivary gland and sinonasal (SGSN) tumours has significantly increased our knowledge about their molecular pathology and classification.

METHODS AND RESULTS

We developed a new targeted multiplexed next-generation sequencing (NGS)-based method that utilizes ligation dependent reverse-transcriptase polymerase chain reaction (LD-RT-PCR) to detect oncogenic fusion transcripts involving 116 genes, leading to 96 gene fusions known to be recurrently rearranged in these tumours. In all, 180 SGSN tumours (formalin-fixed, paraffin-embedded samples, 141 specimens and 39 core needle biopsies) from the REFCORpath (French network for rare head and neck cancers) with previously identified fusion genes by fluorescent in situ hybridisation (FISH), RT-PCR, or molecular immunohistochemistry were selected to test its specificity and sensitivity and validate its diagnostic use. Tested tumours encompassed 14 major tumours types, including secretory carcinoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, salivary gland intraductal carcinoma, clear cell carcinoma, pleomorphic adenoma, adamantinoma-like Ewing Sarcoma, EWSR1::COLCA2 sinonasal sarcoma, DEK::AFF2 sinonasal carcinoma, and biphenotypic sinonasal sarcoma. In-frame fusion transcripts were detected in 97.8% of cases (176/180). Gene fusion assay results correlated with conventional techniques (immunohistochemistry [IHC], FISH, and RT-PCR) in 176/180 tumours (97.8%).

CONCLUSION

This targeted multiplexed NGS-based LD-RT-PCR method is a robust, highly sensitive method for the detection of recurrent gene fusions from routine clinical SGSN tumours. It can be easily customized to cover new fusions. These results are promising for implementing an integrated NGS system to rapidly detect genetic aberrations, facilitating accurate, genomics-based diagnoses, and accelerate time to precision therapies in SGSN tumours.

Top Ten Oncocytic Head and Neck Lesions to Contemplate

BACKGROUND

Oncocytes are a component of many metaplastic and neoplastic lesions throughout the head and neck area, primarily originating in salivary/seromucinous glands and the thyroid gland. In addition, other lesions can contain cells that mimic oncocytes (pseudo-oncocytes); these can be of epithelial or non-epithelial origin.

METHODS

Review article.

RESULTS

Oncocytic metaplasia is common in seromucinous glands throughout the upper aerodigestive tract, most notable in the oral cavity, nasopharynx and larynx. The main oncocytic salivary gland neoplasms are Warthin tumor and oncocytoma. Infarction of Warthin tumor may lead to recognition difficulties. Oncocytic subtypes of mucoepidermoid carcinoma and intraductal carcinoma have morphologic and immunohistochemical features that allow distinction from major oncocytic entities. Oncocytic thyroid tumors include adenoma, carcinoma (follicular, papillary and medullary), along with poorly differentiated tumors. Oncocytic papillary sinonasal and middle ear tumors must be distinguished from low grade adenocarcinomas. Pseudo-oncocytic entities include paraganglioma, Langerhans cell histiocytosis, giant cell tumor, rhabdomyoma, and metastatic tumors.

CONCLUSIONS

Correct diagnosis of oncocytic head and neck lesions requires a knowledge of the spectrum of possible entities, their characteristic sites of occurrence, architecture, histomorphology, and immunohistochemistry. Oncocytic subtypes of several newly described entities are now recognized. Both epithelial and non-epithelial mimics of oncocytes exist. The molecular features of oncocytic tumors can be helpful in their diagnosis and understanding their pathogenesis.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumours: Tumours of the Ear

In the recently published 5th Edition of the World Health Organisation Classification of Head and Neck Tumours, there are relatively few changes to report in terms of nomenclature in lesions of ear and temporal bone and fewer developments in molecular pathogenesis in comparison to other sites, particularly in sinonasal tract. Ear and temporal bone tumours are rare and biopsy material is limited. As a result, resources in the literature are scarce with few large series, no controlled clinical trials and the approaches to staging and management are not standardised. New entities are difficult to characterise. The number of entries has, however, increased for tumours of the ear and temporal bone (thirteen) compared to the 4th Edition (eleven). Some lesions previously included in the 4th Edition considered to have no site-specific features have been excluded to be discussed elsewhere and other benign lesions that are specific to this site have been included. The tumours and tumour-like entities of ear and temporal bone are discussed here mindful that the chapter in the 5th edition better correlates disease processes with clinical information and imaging and as far as possible standardises nomenclature.

Head and Neck Low-Grade Fibromyxoid Sarcoma: A Clinicopathologic Study of 15 Cases

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon mesenchymal tumor usually arising in the lower extremities and trunk. Only rare examples in the head and neck region have been reported. Fifteen cases of head and neck LGFMS were retrieved. MUC4 was performed on all cases. Results for smooth muscle actins, β-catenin, desmin, S100 protein, Epithelial membrane antigen (EMA) and STAT6 immunohistochemistry, as well as FUS rearrangement status, were recorded when available. Sites included neck (8), supraclavicular region (4) and orbit (1), parapharyngeal space (1) and lower lip (1). The age of the patients ranged from 3 to 97 years (median, 26 years). Tumors displayed classical morphologic features of LGFMS, as described. All cases (15/15) were positive for MUC4, and all cases tested (4/4) harbored FUS rearrangement. Variable positivity for EMA was identified in one case. Follow-up was available in 11 patients, ranging from 2 to 240 months (mean 71.4 months; median, 44 months). Three tumors recurred locally; none metastasized. In conclusion, although distinctly uncommon, LGFMS may arise in the head and neck region and should be distinguished from other more common spindle cell tumors in these locations. The morphologic, immunohistochemical and molecular genetic features of head/neck LGFMS are identical to those occurring elsewhere. The long-term metastatic risk of LGFMS in these locations remains to be fully elucidated.

Endolymphatic sac tumor: single-institution series of seven cases with updated review of literature

BACKGROUND

Endolymphatic sac tumour (ELST) is a rare low-grade locally aggressive neoplasm arising from the endolymphatic duct or sac. It presents mostly with vestibulo-cochlear symptoms either sporadically or as part of von Hippel-Lindau (VHL) syndrome. Micro-neurosurgical excision remains the cornerstone of therapy with the role of radiotherapy (RT) being controversial. This is a clinico-pathological analysis of consecutive ELST patients presenting to a single-institution in India.

METHODS

Neuropathology database of a tertiary-care comprehensive cancer centre was searched electronically to identify consecutive patients with histopathological diagnosis of ELST registered at the institute over last one decade. Data regarding demographic profile, clinical presentation, histopathological features, treatment details and outcomes were retrieved from electronic medical records for this retrospective analysis.

RESULTS

Electronic search identified seven unique patients with biopsy-proven ELST registered at the institute between 2009 and 2020. Median age of the study cohort was 39 years (range 24-65 years) with strong male predilection (5:2 ratio) and left-sided preponderance (71%). Most common presenting symptoms were hearing loss (86%) and earache (71%) on affected side followed by headache (43%). All patients underwent maximal safe resection at initial diagnosis and were followed-up closely with periodic surveillance imaging. Two patients underwent salvage RT using high-precision conformal techniques at recurrence/progression.

CONCLUSION

ELST is a rare low-grade locally aggressive neoplasm that arises generally as part of VHL syndrome or sometimes sporadically. Gross total resection provides the best chance of cure with RT being reserved for unresectable disease, large residue, medical inoperability, or as salvage therapy for recurrent/progressive tumor.