Polymorphous adenocarcinoma of the salivary glands: reappraisal and update

Polymorphous Adenocarcinoma: A Systematic Review of the Literature and Presentation of Two Cases in a Less-Considered Anatomical Site

BACKGROUND

Polymorphous adenocarcinoma (PAC) is the second-most common malignant tumour of the minor salivary glands. Although PAC predominantly affects the palate, it can also involve the buccal mucosa. This systematic review aims to investigate the literature data about PAC. Furthermore, we report two cases of patients affected by PAC in an infrequently considered anatomical site.

METHODS

According to PRISMA guidelines, a systematic review search was conducted on PubMed, Scopus, and Web of Science. Observational studies conducted on patients with a histological diagnosis of PAC were selected and analysed. Furthermore, two cases of patients with PAC affecting the buccal mucosa were reported.

RESULTS

Twenty-nine studies were included, and 143 patients affected by PAC were analysed (62 males, 75 females, and 6 undefined, with a mean age of 57.4 ± 14.5 years). The palate was the most affected site (99/143, 69.2%), followed by the buccal mucosa (12/143, 8.4%). Moreover, we report two cases of patients with PAC affecting the buccal mucosa (one male and one female, with a mean age of 70.5 ± 2.5 years).

CONCLUSIONS

The present study underscores the importance of considering the buccal mucosa as a possible location of minor salivary gland tumours; although it is a less-considered affliction, it is not uncommon.

High-grade transformation of a polymorphous adenocarcinoma of the salivary gland: a case report and review of the literature

Background

Polymorphous adenocarcinoma (PAC) represents the second most widespread neoplasm of the minor salivary glands. These tumors rarely develop a histological progression from low-grade to high-grade malignancy, named "high-grade transformation" (HGT). Only nine cases are described in literature.

Case description

Here, we describe the case of a 76-year-old male patient with a PAC recurrence of the oral floor displaying HGT, and we explore the tumor cytomorphological features, genomic profiling, and the patient's clinical management. The tumor mass was characterized by poorly atypical cellular elements with vesicular nuclei and comedonecrosis foci. The growth pattern was predominantly solid, tubular, and cribriform. The lesion did not show microsatellite instability or targeted molecular alterations. The case was successfully treated with radical surgery followed by radiotherapy.

Conclusion

We report for the first time the recurrence of a PAC with HGT arising in the oral floor after 20 years from the primary lesion. These preliminary data and the literature analysis enhance the knowledge of this extremely rare disease.

Mistaken identity of polymorphous low-grade adenocarcinoma treated as periapical lesion in anterior maxilla: A case report

This report presents a rare case of polymorphous low-grade adenocarcinoma (PLGA) in the anterior maxilla, mimicking a periapical lesion. A 56-year-old male reported with a painless swelling in the maxillary right canine-premolar region. The patient gave a history of root canal therapy for the same teeth one month ago. On intraoral examination, the involved teeth were restored with ceramic crowns. Radiographic examination revealed inadequate obturation with an ill-defined radiolucency in the periapical region. 3D cone beam computer tomography (CBCT) revealed erosion of the buccal cortical plate near the apices of the roots. Endodontic re-treatment was performed on both the teeth. Following this, the lesion was excised and submitted for histopathological analysis wherein it was identified as PLGA. Computerised tomographic (CT) scan and positron emission tomography scan (PET) results showed no regional or distant metastasis. Under general anaesthesia, the teeth were extracted, and wide surgical excision of the anterior maxilla was done till the healthy bone was exposed. Healing was uneventful during the follow-up period.

Minor Salivary Gland Polymorphous Adenocarcinoma With Local Recurrence After Seven Years: A Case Report

Polymorphous adenocarcinoma is a rare neoplasm of the minor salivary glands with an indolent behavior. Here, we report and describe the computed tomography (CT) and magnetic resonance imaging (MRI) of polymorphic adenocarcinoma in a 69-year-old patient who presented with local recurrence seven years after the initial treatment. On contrast CT, the primary lesion appeared heterogeneous and invaded the pterygopalatine fossa and the sphenopalatine foramen. The recurrent lesion on MRI showed a hypointense signal on the T1-weighted sequence, a hyperintense signal on the T2-weighted sequence, and heterogeneous enhancement with contrast. The patient underwent a new surgery for lesion resection and is currently under clinical and radiological follow-up. It is recommended to follow patients for at least 15 years after diagnosis, as local recurrences can occur up to 10 years after the initial treatment.

Cribriform adenocarcinoma of the minor salivary glands: a case report

BACKGROUND

Polymorphous adenocarcinoma is the third most common malignant salivary gland tumor. Within polymorphous adenocarcinoma, cribriform adenocarcinoma of salivary glands is a rare subtype and resembles papillary thyroid carcinoma histopathologically. Diagnostically, cribriform adenocarcinoma of salivary glands is challenging for pathologists and surgeons alike as initial presentation and cytologic nuclear features can be easily confused with papillary thyroid carcinoma arising from a thyroglossal duct remnant or lingual thyroid.

CASE PRESENTATION

A healthy 64-year-old Caucasian woman presented to a community otolaryngologist with a 4-year history of progressive postnasal drip, globus sensation, and eventual dysphonia. Flexible fiberoptic laryngoscopy showed a large, smooth, vallecular lesion filling the oropharynx. Computed tomography imaging of the neck showed a rounded heterogeneous mass centered within the right aspect of the oropharynx measuring 4.2 × 4.4 × 4.5 cm. Fine needle aspiration biopsy was suspicious for papillary carcinoma due to microscopic findings of malignant cells, nuclear grooves, and a powdery chromatin pattern. In the operating room, the tumor was resected en bloc using a lateral pharyngotomy approach with partial resection of the right lateral hyoid. A limited cervical lymphadenectomy was performed to facilitate the lateral pharyngotomy approach and two out of three lymph nodes demonstrated regional metastatic disease. Nuclear grooves, nuclear membrane notching, and occasional intranuclear pseudoinclusions were identified, which are overlapping histopathological characteristics of papillary thyroid carcinoma and cribriform adenocarcinoma of salivary glands. It was negative for thyroglobulin and thyroid transcription factor-1, which was in keeping with cribriform adenocarcinoma of salivary glands rather than papillary thyroid carcinoma.

CONCLUSION

It is difficult to distinguish cribriform adenocarcinoma of salivary glands from papillary thyroid carcinoma solely by cytology, and the distinct characteristics of regional lymph node metastasis coupled with nuanced histologic differences should be emphasized in the evaluation of patients presenting with neck lymphadenopathy and an unknown primary or tongue mass. If sufficient fine needle aspiration biopsy material is available, thyroid transcription factor-1, thyroglobulin, or molecular testing may prove useful in differentiating cribriform adenocarcinoma of salivary glands from papillary thyroid carcinoma. A misdiagnosis of papillary thyroid carcinoma may lead to inappropriate treatment including unnecessary thyroidectomy. Therefore, it is critical for both pathologists and surgeons to be aware of this uncommon entity to avoid misdiagnosis and subsequent mismanagement.

Minor Salivary Gland Cancer of the Head and Neck: A Review of Epidemiologic Aspects, Prognostic Factors, and Outcomes

PURPOSE OF REVIEW

Minor salivary gland carcinomas (MiSGC) of the head and neck are a group of rare cancers with significant heterogeneity in histological types and with variable clinical behavior. This study aims to clarify the incidence, epidemiology, predictive factors, and outcome-based survival in a large cohort of patients treated at the Brazilian National Cancer Institute (BNCI) over a 20-year period by comparing and associating the results of current articles on the world stage.

RECENT FINDINGS

The difficulty in developing an algorithm of treatment is due to the low number of cases when evaluated in a single institution and the variety of histological subtypes that have different behaviors and different treatments according to each anatomical location. We reviewed the experience of tertiary centers for the treatment of head and neck cancer and epidemiological studies from the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute of the USA. The lack of consensus on the management of MiSGC requires further knowledge about the biological behaviors of these tumors, as the identification of predictive factor of failure and survival to adequate treatment intensity. The growing collaboration of different centers publishing their experience allows us to unify these samples to reach concrete conclusions about these tumors.

Salivary gland cancer: ESMO-European Reference Network on Rare Adult Solid Cancers (EURACAN) Clinical Practice Guideline for diagnosis, treatment and follow-up

•This ESMO–EURACAN Clinical Practice Guideline provides key recommendations for managing salivary gland cancer. •The guideline covers clinical and pathological diagnosis, staging and risk assessment, treatment and follow-up. •Treatment algorithms for parotid, submandibular, sublingual and minor salivary gland cancer are provided. •The author group encompasses a multidisciplinary group of experts from different institutions and countries in Europe. •Recommendations are based on available scientific data and the authors’ collective expert opinion.

Salivary gland cancers in elderly patients: challenges and therapeutic strategies

Salivary gland carcinomas (SGCs) are the most heterogeneous subgroup of head and neck malignant tumors, accounting for more than 20 subtypes. The median age of SGC diagnosis is expected to rise in the following decades, leading to crucial clinical challenges in geriatric oncology. Elderly patients, in comparison with patients aged below 65 years, are generally considered less amenable to receiving state-of-the-art curative treatments for localized disease, such as surgery and radiation/particle therapy. In the advanced setting, chemotherapy regimens are often dampened by the consideration of cardiovascular and renal comorbidities. Nevertheless, the elderly population encompasses a broad spectrum of functionalities. In the last decades, some screening tools (e.g. the G8 questionnaire) have been developed to identify those subjects who should receive a multidimensional geriatric assessment, to answer the question about the feasibility of complex treatments. In the present article, we discuss the most frequent SGC histologies diagnosed in the elderly population and the relative 5-years survival outcomes based on the most recent data from the Surveillance, Epidemiology, and End Results (SEER) Program. Moreover, we review the therapeutic strategies currently available for locoregionally advanced and metastatic disease, taking into account the recent advances in precision oncology. The synergy between the Multidisciplinary Tumor Board and the Geriatrician aims to shape the most appropriate treatment pathway for each elderly patient, focusing on global functionality instead of the sole chronological age.

Polymorphous Adenocarcinoma: High-Grade Transformation With Immunohistochemical Workup

Intraoral tumours associated with mucosa are commonly oral squamous cell carcinomas followed by minor salivary gland carcinomas, the commonest being mucoepidermoid carcinoma, adenoid cystic carcinoma, and polymorphous adenocarcinoma (PAC). PAC is the second most common malignant tumour that is found in the minor salivary glands of the oral cavity and rarely exhibits high-grade transformation (HGT). We report a case of a 50-year-old woman with a tumour on her buccal mucosa for six months. Histopathologically, the tumour showed more than 15 histopathological patterns with areas of HGT. The high-grade transformed areas predominantly showed solid patterns, increased mitosis, necrosis, vascular invasion, and perineural invasion. An immunohistochemical (IHC) panel inclusive of p63, SOX-10, S-100, calponin, vimentin, and Ki-67 was done to evaluate the tumour and grade PAC. The Ki-67 index was around 25%-30%, confirming the diagnosis of PAC-HGT. This might be the first case of primary PAC-HGT seen on the buccal mucosa on initial clinical presentation.

[Penile metastasis of a carcinoma of the salivary glands at the tongue base: a case report]

We report the case of a 64-year-old man, initially diagnosed with a polymorphous adenocarcinoma of the small salivary glands at the tongue base, with occurrence of a penile metastasis ten years after diagnosis. To our knowledge, only two such cases have been described in the literature to date.

Undifferentiated and dedifferentiated head and neck carcinomas

Undifferentiated carcinomas arising at salivary gland and head and neck mucosal sites may originate either de novo or through a process of dedifferentiation of a differentiated carcinoma. While in the latter group the diagnosis is largely dependent on the identification of the differentiated component or recognition of a specific genotype, the classification of undifferentiated carcinomas that lack a differentiated component is mainly based on the identification of specific genetic drivers, like for example the NUTM1 fusions in NUT carcinoma. A further category is represented by virus associated carcinomas (mainly HPV and EBV), that frequently displays an undifferentiated morphology. Overall, these tumors often represent a diagnostic challenge, especially in small biopsies. This review summarizes and discuss the diagnostic approach to the main head and neck carcinoma types that frequently or occasionally display an undifferentiated appearance, with a focus on salivary gland, oropharyngeal, nasopharyngeal and sinonasal subsites.

Canalicular adenoma: palatal presentation of an uncommon lesion

Canalicular adenoma is a unique, rare, benign salivary gland neoplasm whose reported prevalence varies in different studies. According to literature, this neoplasm has a marked predilection to occur in the upper lip of elderly women. Histological features are usually distinctive and diagnostic. This neoplasm has good prognosis after conservative surgical management but the propensity of multifocal nature and recurrence of this lesion mandates regular follow-up. This case report illustrates the case of a canalicular adenoma in the palate in a 71-year-old male patient. Here, we discuss the differential diagnosis with a brief review of literature.

Classic polymorphous adenocarcinoma: Fine needle aspiration cytopathology of eight cases

INTRODUCTION

The cytopathology and diagnostic accuracy of salivary gland (SG) polymorphous adenocarcinoma (PAC) is the subject of a limited number of reports. We undertook a review of our experience with fine needle aspiration (FNA) biopsy and PAC.

MATERIALS AND METHODS

A search was made of our cytopathology files for PAC cases that also had histopathological confirmation. FNA biopsy smears and cell-blocks were performed and examined using standard techniques.

RESULTS

Eight FNA biopsy cases of histologically proven PAC from 7 patients [F:M = 1.3:1, age 39-75 years, mean = 58] met study inclusion. Metastatic aspirates were most common (4), followed by 3 primary cases and 1 locally recurrent neoplasm. Primary FNA sites included hard palate (1 case), lip (1), and lateral tongue (1); all metastatic sites were in the neck. A precise cytologic diagnosis was made in 38% of cases; however, when applying the Milan classification system, 100% could be categorised as either malignant or of uncertain malignant potential. Ancillary immunohistochemical testing performed in 44% of the cases was non-specific. Cytologic smears showed cellular uniformity and structural variety of cell groups with tubular, branching, cribriform, and convex patterns as well as variable, but occasionally abundant globular myxoid stroma leading to confusion with adenoid cystic carcinoma.

CONCLUSION

The imitative cytopathology of PAC with other SG neoplasms as well as its infrequency in routine FNA biopsy practice makes specific interpretation difficult, but using a classification system allows for appropriate patient management. Molecular testing in future specimens holds promise for enhancing diagnostic accuracy.

High-grade Transformation/Dedifferentiation in Salivary Gland Carcinomas: Occurrence Across Subtypes and Clinical Significance

High-grade transformation (HGT) or dedifferentiation has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, secretory carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous adenocarcinoma, low-grade mucoepidermoid carcinoma, and hyalinizing clear cell carcinoma. High-grade (HG) transformed tumors are composed of a conventional low-grade component characterized by specific microscopic and immunohistochemical features for the given entity, intermingled with or juxtaposed to areas of HG morphology. This is usually either poorly differentiated adenocarcinoma, carcinoma not otherwise specified, or undifferentiated carcinoma, in which the original line of differentiation is lost. The HG component is composed of solid nests of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. Frequent mitoses and extensive necrosis may be present. The Ki-67 labeling index is consistently higher in the HG component. The molecular genetic mechanisms responsible for HGT of salivary gland carcinomas are largely unknown, though p53 inactivation and human epidermal growth factor receptor 2 overexpression and/or gene amplification have been demonstrated in the HG component in a few examples, the frequency varies for each histologic type. Salivary gland carcinomas with HGT are more aggressive than conventional carcinomas, with a higher local recurrence rate and a poorer prognosis. They have a high propensity for cervical lymph node metastasis suggesting a need for a wider resection and neck dissection. HGT of salivary gland carcinoma can occur either at initial presentation or less commonly at the time of recurrence, sometimes following postoperative radiotherapy. The potential for HGT in almost any type of salivary gland carcinoma warrants a thorough sampling of all salivary gland malignancies to prevent oversight of a HG component.

Pleomorphic adenoma: the great mimicker of malignancy

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, and its diagnosis is straightforward in the majority of cases. However, not infrequently, PA shows unusual and uncommon histological features that can be confused with those of malignancy. The difficulties in diagnosing PA arise from its ability to mimic invasion, show atypical or metaplastic cytomorphology, and show morphological features that overlap with those of established salivary gland carcinomas. In addition, recognising early malignant transformation to carcinoma ex-pleomorphic adenoma continues to be a frequent challenge. This review describes the diagnostic pitfalls of PA, and offers a systematic approach to avoid them by combining classic histopathology with novel immunohistochemical and molecular tests.

SalvGlandDx - a comprehensive salivary gland neoplasm specific next generation sequencing panel to facilitate diagnosis and identify therapeutic targets

Diagnosis of salivary gland neoplasms is often challenging due to their high morphological diversity and overlaps. Several recurrent molecular alterations have been described recently, which can serve as powerful diagnostic tools and potential therapeutic targets (e.g. NTRK or RET fusions). However, current sequential molecular testing can be expensive and time consuming. In order to facilitate the diagnosis of salivary gland neoplasms, we designed an all-in-one RNA-based next generation sequencing panel suitable for the detection of mutations, fusions and gene expression levels (including NR4A3) of 27 genes involved in salivary gland neoplasms. Here we present the validation of the "SalvGlandDx" panel on FFPE histological specimen including fine needle aspiration (FNA) cell block material, against the standard methods currently used at our institution. In a second part we describe selected unique cases in which the SalvGlandDx panel allowed proper diagnosis and new insights into special molecular characteristics of selected salivary gland tumors. We characterize a unique salivary gland adenocarcinoma harboring a ZCCHC7-NTRK2 fusion, a highly uncommon spindle cell and pseudoangiomatoid adenoid-cystic carcinoma with MYBL1-NFIB fusion, and a purely oncocytic mucoepidermoid carcinoma, whereas diagnosis could be made by detection of a CRTC3-MAML2 rearrangement on the cell block specimen of the FNA. Further, a rare case of a SS18-ZBTB7A rearranged low-grade adenocarcinoma previously described as potential spectrum of microsecretory adenocarcinoma, is reported. In addition, features of six cases within the spectrum of polymorphous adenocarcinoma / cribriform adenocarcinoma of salivary gland including PRKD1 p.E710D mutations and novel fusions involving PRKAR2A-PRKD1, SNX9-PRKD1 and ATL2-PRKD3, are described.

Magnetic resonance imaging of salivary gland tumours: Key findings for imaging characterisation

Salivary gland tumours are rare, representing only 3% of all head and neck neoplasms, with the parotid gland being the most common site (80 %). The risk of malignancy is inversely proportional to the size of the gland: lesions arising in the sublingual or minor salivary glands are more likely to be malignant, whereas parotid gland neoplasms are mostly benign. Fine needle aspiration cytology and core needle biopsy are considered the most accurate modalities for the diagnosis of a salivary gland neoplasm; however, they are not always conclusive due to procedural sampling errors and for the presence of a cytological / histological overlap between benign and malignant tumours. Moreover, they cannot be easily performed for parotid deep portion localisation. The role of magnetic resonance imaging (MRI) is growing and advanced techniques (diffusion-weighted and dynamic contrast-enhanced perfusion-weighted imaging) can provide useful additional information for the assessment of salivary gland neoplasms. The aim of this review is to present the main MRI and clinical features of salivary gland tumours to improve their comprehensive evaluation and characterisation.

[Malignant tumors of the oral cavity]

Klinisches/methodisches Problem

Mundhöhlenmalignome stellen weltweit die häufigsten Tumoren im Bereich der Hals-Nasen-Ohrenheilkunde bzw. Otorhinolaryngologie dar. Es handelt sich um eine heterogene Gruppe an Tumoren, deren Kenntnis erforderlich ist, um den unterschiedlichen Anforderungen an Diagnostik und Therapie gerecht zu werden.

Radiologische Standardverfahren

Computertomographie (CT), Magnetresonanztomographie (MRT), Sonographie, nuklearmedizinische Verfahren (NUK).

Leistungsfähigkeit

Die o. g. Diagnostika werden komplementär eingesetzt.

Bewertung

Eine frühzeitigere Diagnose des Tumors verbessert das Staging und somit die Therapie und Prognose des Patienten.

Schlussfolgerung

Dem Radiologen kommt bei der interdisziplinären Behandlung von Malignomen der Mundhöhle eine bedeutende Rolle zu. Trotz großer Fortschritte in der Radiotherapie, Onkologie und Immuntherapie spielt die Chirurgie weiterhin eine wichtige Rolle in der Behandlung maligner Erkrankungen der Mundhöhle.

Primary Pituitary Adenoid Cystic Carcinoma: A Rare Salivary Gland-Like Tumor in the Sella

Adenoid cystic carcinoma (ACC) is a tumor of the exocrine glands that originates primarily from the minor and major salivary glands, nasopharynx, and lacrimal glands. ACC grows slowly but is locally aggressive and prone to recurrence. It is uncommon for ACCs to develop in the pituitary gland as a primary tumor. We present a case of primary pituitary ACC extending to the sphenoid sinus resembling an invasive adenoma in a 71-year-old woman with a history of nasal epistaxis. We reviewed other reported cases of pituitary ACCs with retrospective validation of whether the tumor was primary or not. The intrasellar tumor exhibited MYB rearrangement with enlargement and destruction of the sella turcica and dural tears toward the sphenoid sinus, which would be consistent for a tumor originating from the pituitary gland. Including our case, only four intrasellar and one suprasellar ACC have been confirmed as primary tumors. All intrasellar ACCs had the characteristic of some form of invasion of neighboring structures with evidence of hyperprolactinemia. ACC could develop in the pituitary gland as a form of salivary gland-like tumor derived from the ectopic salivary gland rests. ACCs rarely arise from the pituitary gland; however, the accurate determination of primary occurrence is difficult because of the invasive nature of these tumors, and the anatomical relationship with the sphenoid sinus and the cavernous sinus. Excessive bleeding from the tumor or unexpected internal carotid artery injury should be avoided during surgery for primary and secondary pituitary ACC.

Role of elective neck dissection and adjuvant radiation therapy in patients with polymorphous adenocarcinoma

PURPOSE

To evaluate the role of elective neck dissection (END) and of adjuvant radiation (aRT) in polymorphous adenocarcinoma (PAC), previously known as polymorphous low-grade adenocarcinoma (PLGA).

METHODS

Retrospective cohort study of patients in the National Cancer Database with a histology of PAC (coded as PLGA) at a head and neck site diagnosed between 2004 and 2015. Multivariable Cox proportional hazard modeling was used to assess overall survival in the overall population, and in sub-analyses of clinically N0 disease, positive resection margins, and late stage disease.

RESULTS

A total of 922 patients [66.8% female; mean (SD) age, 60.9 (13.9) years] met inclusion criteria. 74.7% of patients received surgery alone, and 18.0% received surgery and aRT. Only 7.6% of patients with clinically N0 disease received an END, with 10.6% of these having at least one positive node. END did not have a survival benefit compared to no END [HR 1.28 (0.61-2.68)]. Compared to surgery alone, aRT did not have significantly increased survival in the overall population or in late stage [HR 0.68 (0.39-1.19) and HR 0.46 (0.18-1.22), respectively]. On sub-analysis of patients with positive resection margins, aRT had a significant survival benefit compared to surgery alone [HR 0.37 (0.14-0.99)].

CONCLUSION

PAC is a rare, slow-growing malignant tumor typically treated with surgical excision, with undefined indications for END or aRT. Our findings show END to not have a benefit to overall survival. In patients with positive resection margins, there was a survival benefit for aRT.

Clinicopathological Features of Thyroid-Like Low-Grade Nasopharyngeal Papillary Adenocarcinoma: A Case Report and Review of the Literature

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TL-LGNPPA) is an extremely rare neoplasm of the nasopharynx. Accordingly, its clinical and pathological characteristics are not well-known. We report a case of TL-LGNPPA and review the relevant literature on TL-LGNPPA. A 38-year-old Japanese woman presented with a history of nasal obstruction that had persisted for 1 month after symptoms of a common cold (e.g., low-grade fever, sore throat, and fatigue). A pedunculated tumor of ~20 mm in diameter was found on the posterior edge of the nasal septum. The tumor was endoscopically resected. Based on careful histopathological and immunohistochemical examinations, it was diagnosed as TL-LGNPPA. At 5 years after surgery, the patient remained disease-free. TL-LGNPPA has a very good prognosis, and complete resection with a sufficient safety margin is recommended as the first-line treatment. The morphological characteristics and immunohistochemical findings, especially TTF-1 positivity and thyroglobulin negativity, are important for the diagnosis.

Fine needle aspiration cytology of polymorphous adenocarcinoma of the salivary glands: A report of 11 patients and review of the literature

BACKGROUND

Polymorphous adenocarcinoma (PAC) is a rare malignant tumor of the minor salivary glands. It has an infiltrative growth, variable architectural patterns, neurotropism and cellular monomorphism. Approximately 75% of the cases show a specific mutation in the protein kinase D1 (PRKD1) gene. Reflecting the rarity of the tumor and intraoral location, the cytologic experience is limited with few reported series. In this study we analyze our cytologic experience to determine if a preoperative diagnosis is possible.

METHODS

A retrospective study of 11 patients with PAC in which a cytologic study was available. A review of the literature was also performed.

RESULTS

Our study shows that PAC has relatively constant cytological features. The analysis of the cytological literature although it shows some heterogeneity, also reveals repetitive cytological findings. Smears are cellular with irregular groups some showing pseudopapillary branching morphology. Monolayered clusters and small acinar structures are also present. Most cases have small metachromatic globules embedded within the groups determining a cylindromatous pattern. Tumoral cells are small and uniform with scarce to moderate cytoplasm. Nuclei are round and oval with occasional grooves and small nucleoli.

CONCLUSION

PAC has characteristic cytological features that together with its location in minor salivary gland must make us consider it preoperatively. It may resemble basal cell adenoma and epithelial-rich pleomorphic adenoma so we should be cautious in the final diagnosis. Whenever possible, the characteristic cytomorphology of PCA should make us evaluate the mutational status of PRKD1 gene since it may permit a more accurate diagnosis.

Advances and challenges in precision medicine in salivary gland cancer

Salivary gland cancer (SGC) is a rare malignancy consisting of 22 subtypes with different genetic, histological and clinical characteristics. This rarity and heterogeneity makes systemic treatment of recurrent or metastatic (R/M) disease challenging. Use of chemotherapy is scarcely studied and chemotherapy at best has moderate effects. New therapeutic strategies are therefore warranted, but advances made in SGC are lagging behind on advances made in more common cancers. By unraveling tumor characteristics of SGC, such as genetic alterations and protein expression profiles, therapeutic strategies tailored to the patient's tumor can be rationalized. This genomic profiling and mapping of immunohistochemical expression profiles is essential in the search for a suitable treatment approach. Thereby, it alleviates the paucity in systemic treatment options and can significantly alter the prognosis of patients with R/M SGC. This review aims to give a comprehensive overview of known genetic alterations and expression profiles amenable for targeted therapy in every histological subtype of SGC. We discuss the remaining knowledge gaps and the implications of these targets for future studies and personalized treatments, thereby aiding clinicians faced with this rare and heterogeneous type of cancer.

Analysis of the Clinical Relevance of Histological Classification of Benign Epithelial Salivary Gland Tumours

INTRODUCTION

A vast increase in knowledge of numerous aspects of malignant salivary gland tumours has emerged during the last decade and, for several reasons, this has not been the case in benign epithelial salivary gland tumours. We have performed a literature review to investigate whether an accurate histological diagnosis of the 11 different types of benign epithelial salivary gland tumours is correlated to any differences in their clinical behaviour.

METHODS

A search was performed for histological classifications, recurrence rates and risks for malignant transformation, treatment modalities, and prognosis of these tumours. The search was performed primarily through PubMed, Google Scholar, and all versions of WHO classifications since 1972, as well as numerous textbooks on salivary gland tumours/head and neck/pathology/oncology. A large number of archival salivary tumours were also reviewed histologically.

RESULTS

Pleomorphic adenomas carry a considerable risk (5-15%) for malignant transformation but, albeit to a much lesser degree, so do basal cell adenomas and Warthin tumours, while the other eight types virtually never develop into malignancy. Pleomorphic adenoma has a rather high risk for recurrence while recurrence occurs only occasionally in sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and the membranous type of basal cell adenoma. Papillomas, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (solid, trabecular and tubular subtypes) very rarely, if ever, recur.

CONCLUSIONS

A correct histopathological diagnosis of these tumours is necessary due to (1) preventing confusion with malignant salivary gland tumours; (2) only one (pleomorphic adenoma) has a considerable risk for malignant transformation, but all four histological types of basal cell adenoma can occasionally develop into malignancy, as does Warthin tumour; (3) sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and Warthin tumour only occasionally recur; while (4) intraductal and inverted papilloma, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (apart from the membranous type) virtually never recur. No biomarker was found to be relevant for predicting recurrence or potential malignant development. Guidelines for appropriate treatment strategies are given.

Updated WHO nomenclature of head and neck lesions and associated imaging findings

This article reviews the imaging features of head and neck lesions with updated 2017 World Health Organization (WHO) nomenclature. The major WHO changes include refined terminology of existing entities, descriptions of new tumor types, elimination of defunct categories, and updated biological characterization of various tumor types. In particular, the updates pertaining to the following conditions will be reviewed: tumors of the oral cavity and oropharynx, including HPV-positive or HPV-negative squamous cell carcinoma, small cell carcinoma; tumors of the hypopharynx, larynx, trachea, and parapharyngeal space, including nomenclature revisions for laryngeal neuroendocrine tumors; tumors of the nasal cavity and paranasal sinuses including newly added entities such as NUT carcinoma and biphenotypic sinonasal sarcoma; odontogenic and maxillofacial bone tumors, including the reversal of terminology for certain cystic lesions; tumors of the salivary glands, including updated terminology related to high-grade transformation and polymorphous adenocarcinomas tumors; temporal bone lesions including modifications of the nomenclature and classification criteria; tumor-like lesions of the neck and lymph nodes, with a discussion encompassing developmental cysts, metastases of unknown primary, and heterotopia-associated neoplasia; and mucosal melanoma. Familiarity with the proper WHO terminology for conditions that might be mentioned in differential diagnoses and a general understanding of the behavior of head and neck lesions can help optimize imaging assessment and reporting.