Natural history of recurrent pleomorphic adenoma: implications on management

Peculiar nuclear atypia associated with MDM2 gene amplification in carcinoma ex-pleomorphic adenoma harbouring an alteration of HMGA2

AIMS

Salivary gland neoplasms (SGN) exhibiting the HMGA2::WIF1 fusion are recognized by their resemblance to histology found in canalicular adenoma. Recently, ~20% of cases among 28 HMGA2::WIF1-rearranged-SGN showed malignancy and adverse outcomes (recurrence, distant metastasis, and disease-specific mortality). Among them, MDM2/CDK4 amplifications were identified in one case. This outcome suggests that the MDM2/CDK4 amplifications could be useful to predict an aggressive course of carcinoma ex-pleomorphic adenoma (CEPA).

METHODS AND RESULTS

We investigated the correlation between HMGA2 fusion and MDM2 amplification in four salivary gland neoplasms, providing detailed clinicopathological features and outcomes. Cases were selected from different institutions. Histological examination, immunohistochemistry, fluorescence in situ hybridization (FISH), RNA sequencing, and whole-exome capture were performed. The cohort included four CEPA cases, all female, aged between 32 and 89 years. Tumours arose from the parotid gland with an average size of 24.5 mm. None exhibited recurrence or distant metastases during the 4-5 months of follow-up. Pathologically, all cases displayed a peculiar atypical nuclei with 'gear-like appearance'. Immunohistochemically, tumours exhibited a biphasic pattern with myoepithelial and ductal differentiation markers. All cases showed HMGA2 overexpression and MDM2 amplification by FISH and RNA sequencing. In a control cohort of MDM2 nonamplified CEPA cases, not exhibiting the peculiar nuclear atypia.

CONCLUSIONS

Our findings suggest a strong correlation between HMGA2 alteration/MDM2 amplification and a peculiar nuclear atypia, advocating for their evaluation in biphasic tumours to facilitate accurate diagnosis and tailored posttumour removal monitoring. Further studies are warranted to validate these observations and elucidate their prognostic implications.

Pleomorphic Adenoma in a Posterior Cervical Soft Tissue Mass: A Diagnostic Conundrum

Diagnosing a soft tissue tumor in the head and neck region can be challenging due to its complex anatomy and diverse histological spectrum. This case report highlights the case of a woman who presented with a painless neck lump in the posterior triangle of the neck. Various pathological and imaging studies were suggestive of pleomorphic adenoma, which arises from the left prevertebral space. The patient underwent complete surgical excision via the transcervical approach. Pleomorphic adenoma in the posterior triangle of the neck is extremely rare and causes a diagnostic dilemma in managing soft tissue tumors of the neck.

Clinical behavior of recurrent pleomorphic adenoma in the palate: a systematic review

PURPOSE

This systematic review analyzed the clinical behavior and odds of malignancy of the palatal recurrent pleomorphic adenomas.

METHODS

Systematic review of patients with recurrent pleomorphic adenoma arising in the palate. Database search: MEDLINE, Scopus, Web of Science, Cochrane, EMBASE, Virtual Health Library, Google Scholar, and OpenGrey. A binomial logistic regression was performed to assess the odds of detecting recurrence five, 10 and 20 years after the treatment of primary tumor.

RESULTS

Thirteen studies (n = 18 patients) out of 336 were included. The recurrent pleomorphic adenoma in palate was more common in females (61.6%), average age was 49 years old (range 9-73 years old). Four patients progressed to malignant transformation. The odds ratio (OR) of detecting a recurrence at 10 (OR = 5.57; 95% confidence interval - 95%CI 1.13-27.52), and 20 years (OR = 18.78; 95%CI 3.18-110.84) after treatment of primary pleomorphic adenoma was significantly higher than at one-year follow-up.

CONCLUSIONS

The recurrence of pleomorphic adenoma in palate remains a rare event of late occurrence. It mainly affects middle-aged female and carries a risk of malignant transformation. Although uncommon, patients with palatal pleomorphic adenoma should be warned about the possibility of recurrence or malignant transformation of tumor at advanced ages.

BubR1 and cyclin B1 immunoexpression in pleomorphic adenoma and polymorphous adenocarcinoma of minor salivary glands

The immunoexpression of BubR1 and cyclin B1 in pleomorphic adenoma (PA) and polymorphic adenocarcinoma (PAC) in minor salivary glands is poorly studied. Thus, a retrospective and observational study was performed to provide a better understanding of the role and immunopositivity patterns of these proteins in these lesions. Sixteen cases of PA and 16 cases of PAC were selected. Parenchyma cells were submitted to quantitative immunohistochemical analysis through the labeling index. Cytoplasmic immunoexpression of BubR1 was observed in neoplastic cells from all analyzed PA and PAC cases. All PA cases and 93.7% of PAC exhibited nuclear immunoexpression of BubR1. Higher cytoplasmic and nuclear immunoexpression of BubR1 was observed in PAC (p = 0.001 and p = 0.122, respectively). Cytoplasmic immunoexpression of cyclin B1 was observed in all cases of PA and PAC, with a higher labeling index in the latter (p < 0.001). There was a significant positive correlation between nuclear and cytoplasmic BubR1 immunoexpressions (p < 0.001) in PA and a significant negative correlation between BubR1 and cyclin B1 cytoplasmic immunoexpressions (p = 0.014) in PAC. The higher cytoplasmic and nuclear immunoexpression of BubR1 in PACs suggests the continuous maintenance of neoplastic cells in the cell cycle and migration. Higher immunoexpression of cyclin B1 supports this lesion's enhanced proliferative and migration ability.

Parotid gland pleomorphic adenoma re-operations with regard to patient and surgeon satisfaction: what can be improved?

BACKGROUND

Surgery, the treatment of choice for parotid pleomorphic adenoma (PA), is associated with facial nerve palsy and decreased quality of life. Re-operation for PA recurrence (rPA) significantly increases these risks and constitutes a dilemma for both patient and surgeon. Factors influencing the success of re-operation, as well as the self-reported satisfaction of both sides, have yet to be addressed in the literature. This study aims to improve upon the decision-making schedule in PA re-operations, based on patient expectations, imaging, and concordance with the first operative report (FOpR).

METHODS

Seventy-two rPAs treated in a single tertiary center were collected and analyzed. The FOpRs and pre-operative imaging were divided according to defined criteria into accurate and non-accurate categories. The re-operative field and course were categorized as anticipated or unanticipated. The re-operation was categorized as satisfactory or unsatisfactory for both the patient and the surgeon.

RESULTS

The accuracy of FOpRs and pre-operative imaging was 36.1% and 69.4%, respectively. Re-operative courses were: 36.1% anticipated and 63.9% unanticipated. The most frequently omitted data were: presence of satellite tumors (9.7%), and amount of removed parenchyma (9.7%). Variables that most commonly affected FOpR non-accuracy were: tumor size (Chi2(1)=59.92; p < 0.001) and capsule condition (Chi2(1)=29.11; p < 0.001). There was no significant relationship between FOpR accuracy and re-operative course (Chi2(1)=1.14; p = 0.286), patient satisfaction (Chi2(1)=1.94; p = 0.164) or surgeon satisfaction (Chi2(1)=0.04; p = 0.837). Pre-operative imaging (Chi2(1)=36.73; p < 0.001) had the greatest impact on surgeon satisfaction.

CONCLUSION

Accurate pre-operative imaging impacted surgeon satisfaction. The impact of the FOpR on re-operation technicalities and patient satisfaction was minor. Imaging precision should be improved to streamline the decision-making process of PA re-operation. This article proposes suggestions for a future decision-making algorithm as a starting point for a prospective study.Key messagesAccurate pre-operative imaging impacts both surgeon and patient satisfaction.There is no significant relationship between the accuracy of the first operative report and surgeon and patient satisfaction.There is a statistically significant relationship between patient and surgeon satisfaction.

Recurrent pleomorphic adenoma of the parotid gland: A population-based study with emphasis on re-recurrence and malignant transformation

BACKGROUND

This study aimed to analyze the prognostic determinants for re-recurrence and malignant transformation of parotid recurrent pleomorphic adenoma (RPA).

METHODS

Between January 2011 and December 2020, all the cases of RPA of the parotid gland at our single institution were reviewed.

RESULTS

A total of 168 patients were included in this study, with a median age of 41.5 years, and 20 (11.9%) patients developed re-recurrence during follow-up. It has been evidenced that recurrence times (single or multiple) was an independent prognostic factor for recurrence-free survival (p = 0.0264). A total of 26 (15.48%) patients experienced malignant transformation of parotid RPA, and older age (>45 year old), male sex, and higher clinical tumor staging (T3-T4) were significantly associated with malignant transformation of parotid RPA.

CONCLUSIONS

Recurrence times was an independent prognostic factor for re-recurrence of parotid RPA, and older male with high T-stage may more easily develop malignant transformation.

Superficial versus total parotidectomy for recurrent pleomorphic adenoma in the parotid gland

Recurrent pleomorphic adenoma (RPA) is a challenging disease because of difficulty in reoperation, a high rate of postoperative facial palsy, and potential malignant transformation. The optimal management of RPA is still arguable regarding the surgical extent and the necessity of radiotherapy. Therefore, this study compared the complication and re-recurrence rates of superficial versus total parotidectomy in a prospective cohort of 29 patients with RPA. Two surgical techniques were allocated to consecutive patients without randomization and blinding processes. Total parotidectomy was applied to lesions in deep or both lobes. Most early and late complication rates were statistically comparable between the two groups (P > 0.05). Transient and permanent facial nerve paralysis frequently occurred in 55 % and 14 % of all cases, respectively, without statistical difference between the two groups (P > 0.5). Only one patient (3 %) had re-recurrence after superficial parotidectomy during the mean follow-up of 89 months. Superficial or total parotidectomy is recommended to reduce the risk of further recurrence in patients with RPA.

Comparative Longitudinal Analysis of Malignant Transformation in Pleomorphic Adenoma and Recurrent Pleomorphic Adenoma

Background: Recurrence in pleomorphic adenoma (PA) has been debated as a risk factor for malignant transformation (MT). In this study, we investigated whether recurrence is a risk factor for MT, by longitudinally analyzing cases with recurrent PA (RPA), and carcinomas from PA (CXPA) or RPA (CXRPA). Methods: The study population included 24 CXPA, 24 RPA, 6 CXRPA, and 386 PA cases (study period 2010−2018). Time and event data were collected from the medical documents to identify the time−event sequences. Results: The time interval to MT in CXRPA was significant longer than that of benign recurrence (median 342.0 vs. 109.5 months). In CXRPA, the recurrence intervals were not shorter than those in RPA according to recurrence frequency. Crudely, the MT rate was 5.9% among primary cases and 20.0% among recurrent cases. However, the time-adjusted MT rates increased up to 11.4% (incubation time > 60 months) and 20.0% (>120 months) in primary cases, which were not different from recurrent cases. Conclusion: In these longitudinal analyses, we did not find any clinical evidence that recurrence facilitates MT in the background of PA. Instead, a long incubation time seems to be a key factor for MT of underlying RPA.

Pleomorphic Adenoma of the Parotid Gland and the Parapharyngeal Space: Two Diametrically Opposing Surgical Philosophies for the Same Histopathologic Entity?

BACKGROUND

The aim of this study was to investigate the histopathologic findings in parotid and parapharyngeal pleomorphic adenomas and draw conclusions concerning the surgical strategy.

METHODS

Retrospective study of medical charts of patients with resected pleomorphic adenomas (PA) between 2005 and 2020 at two tertiary medical referral centers. Histologic specimens were reexamined by an experienced head and neck pathologist. Patients with insufficient/incomplete data were excluded from our study sample.

RESULTS

A total of 844 patients formed our study sample (291 men, 553 women, average age 48.9 years); 786 cases had a PA in the parotid gland (PG) (93.1%), and the remaining 58 cases had a PA in the parapharyngeal space (PS) (6.9%). Recurrences were detected in 8/844 cases (7/786 in the PG, 1/58 in the PS, 0.94% in total) with a mean follow-up time of 86.7 months (10-189 months) with no statistically significant differences between the study groups (p = 0.527). Our analysis showed that parapharyngeal pleomorphic adenomas are characterized by a lower incidence of an intact anatomical capsule (71.4% vs. 82.6%, p = 0.035) and a remarkably more frequent occurrence of satellite nodules (20.7% vs. 7.5%, p < 0.001).

CONCLUSIONS

The more challenging histopathologic profile of parapharyngeal pleomorphic adenomas points towards the fact that parapharyngeal surgery should remain in the hands of experienced surgeons at high-volume centers.

Pleomorphic adenoma: Detection of PLAG1 rearrangement-positive tumor components using whole-slide fluorescence in situ hybridization

AIM

Pleomorphic adenoma (PA) consists of heterogeneous histological architecture mixed with epithelioid and mesenchymal forms. Various types of epithelial or myoepithelial malignancies arise from PA, but sarcomas are extremely rare. A HUMARA clonality assay has suggested that PA is clonal in nature. However, clonality of various tumor components of PA would be difficult to determine with this assay. In addition, the results obtained should be carefully interpreted. PLAG1 rearrangements are considered a good molecular marker for neoplasticity in PA. We aimed to clarify the neoplasticity of the various tumor components present in PA using whole-slide fluorescence in situ hybridization (FISH).

METHODS

Five PA cases positive for PLAG1 rearrangements were examined. Using an immunohistochemistry panel, cell components in PA were classified into eight cell types. To precisely localize PLAG1 rearrangement-positive cell components at the cellular level, sequential retrieval of whole-slide imaging (WSI) data of HE histology and FISH for PLAG1 rearrangement was carried out.

RESULTS

PLAG1 rearrangements were detected in ductal cells, myoepithelial spindle cells, myoepithelial oncocytic cells, myoepithelial plasmacytoid cells, and mesenchymal chondroid cells, but not in mesenchymal lipid cells, mesenchymal fibrous cells, or vascular endothelial cells. Immunohistochemical PLAG1 expression was restricted to cell components harboring PLAG1 rearrangements.

CONCLUSIONS

The results of the present study indicate that ductal and myoepithelial, chondroid cells are neoplastic but lipid, fibrous, and endothelial cells are not. PLAG1 immunohistochemistry is useful in discriminating neoplastic from non-neoplastic cell components. These findings may be important for elucidating tumorigenesis and the process of malignant transformation in PA.

[The influence of the capsular defect as a risk factor for recurrence in pleomorphic adenoma]

OBJECTIVE

 Aim of this study was to enlighten various aspects of the capsular defect of a pleomorphic adenoma and to analyze its influence on recurrence rate with the help of our data and the relevant literature.

MATERIAL AND METHODS

 The clinical records and histopathological findings of all patients who underwent parotidectomy for pleomorphic adenoma between 2006 and 2020 were evaluated retrospectively. The histological slides of all tumours were critically re-evaluated for this study by an experienced head and neck pathologist. The records of the cases with a capsular defect were examined for information on age, gender, type of surgery and surgical outcome.

RESULTS

 A total of 845 patients were included in the primary group. 7 (0.8 %) recurrences were detected, all of these were resected without a capsular rupture. Positive margins were found in 37 cases (4.4 %). In 13/37 cases the capsular defect was detected intraoperatively, whereas the defect was only identified histopathologically in 24 of the 37 cases. In the group of the intraoperative capsular opening, with a median follow-up of 62 months, the sonographic examination suspected a unilocular recurrence of the pleomorphic adenoma in two cases.

CONCLUSION

 The intraoperative capsule opening does not inevitably seem to lead to a pre-programmed recurrence.

Comprehensive characterization of pleomorphic adenoma at intraoral unusual sites

OBJECTIVE

The present study aimed to comprehensively characterize the epidemiologic characteristics, clinicopathologic characteristics, clinical treatments, and prognoses of pleomorphic adenoma (PA) identified at unusual intraoral sites.

STUDY DESIGN

Patients diagnosed with PA in oral and maxillofacial regions at our institution in the past 16 years (2005-2020) were screened from the inpatient disease registry. All data concerning patients with PA found at unusual intraoral sites (defined as intraoral locations except sublingual gland and palate) were retrieved. Previously published cases with adequate clinicopathologic data were collected from PubMed and Embase. Eligible cases were further reviewed and included for statistical analyses.

RESULTS

Among 1039 cases of PA diagnosed at our institution, 52 lesions were found at unusual intraoral sites. A literature review identified another 63 eligible cases from 32 articles. The upper lip was the most common sites for these lesions (n = 57), followed by buccal mucosa (n = 34), tongue (n = 8), lower lip (n = 8), and retromolar area (n = 2). Recurrence and malignant transformation after surgical resection were extremely rare for these lesions.

CONCLUSIONS

PA might rarely develop at uncommon intraoral sites with atypical presentations, thus complicating its early diagnosis. Surgical resection is the major therapeutic strategy for this rare entity and has a favorable prognosis.

Malignant transformation of salivary gland pleomorphic adenoma: proof of principle

Supposed risk of malignant transformation of salivary gland pleomorphic adenoma (SGPA) is an important reason for aggressive retreatment in recurrent pleomorphic adenoma (RPA). However, although the diagnostic category ‘carcinoma ex‐pleomorphic adenoma’ suggests that malignant transformation of a pleomorphic adenoma is a regular event, this has to date not been shown to occur in sequential lesions of one patient. Here, we show the molecular events in transformation to malignancy of a pleomorphic adenoma of the parotid gland. Detailed molecular analysis revealed an LIFR/PLAG1 translocation characteristic for pleomorphic adenoma and, next to this, a PIK3R1 frameshift mutation and several allelic imbalances. In subsequent malignant recurrences, the same LIFR/PLAG1 translocation, PIK3R1 frameshift mutation, and allelic imbalances were present in addition to TP53 mutations. Thus, this case not only shows malignant transformation of SGPA, but also demonstrates that molecular analysis can be of help in recognising malignancy in the rare instance of RPA.

Histopathological comparison of pleomorphic adenomas of the parotid and submandibular gland

OBJECTIVE

The aim of this study was to investigate and compare the histopathological findings in pleomorphic adenomas (PA) of the parotid and submandibular gland with emphasis on the histological subtype and capsular characteristics.

MATERIALS AND METHODS

The histopathological specimens of all patients with PAs of the parotid and submandibular gland between 2000 and 2020 were re-examined by an experienced head and neck pathologist. Patients without representative slides allowing evaluation of the whole periphery of the PA were excluded from our study sample.

RESULTS

Nine hundred and thirty-four patients formed our study sample (327 men, 607 women, male-to-female ratio: 0.53:1). Eight hundred and forty-four cases had a PA in the parotid gland and the remaining 90 in the submandibular gland. Our comparative analysis showed that submandibular PAs are characterized by the consistent presence of an intact anatomical capsule, infrequent occurrence of pseudopodia and satellite nodules, and a low proportion of the high-risk myxoid subtype.

CONCLUSION

Our study highlights significant differences between PAs of the parotid and submandibular glands in their histopathological characteristics. Their differences likely underlie the favorable surgical outcome observed in PAs of the submandibular glands and may explain the propensity of PAs of the parotid glands for local recurrences.

Salivary Gland Pleomorphic Adenomas Presenting With Extremely Varied Clinical Courses. A Single Institution Case-Control Study

Objective

Pleomorphic adenomas (PAs) with divergent clinical behavior, differing from the vast majority of PAs, were distinguished. “Fast” PAs are characterized by an unexpectedly short medical history and relatively rapid growth. The reference group consisted of “slow” PAs with very stable biology and long-term progression. We divide the PA group as a whole into three subsets: “fast,” “normal,” and “slow” tumors. Our goal is a multifactorial analysis of the “fast” and “slow” PA subgroups.

Methods

Consecutive surgeries in a tertiary referral center, the Department of Otolaryngology and Laryngological Surgery, Poznan University of Medical Sciences, Poland, were carried out between 2002 and 2011. Out of 1,154 parotid tumors, 636 (55.1%) were PAs. The data were collected prospectively in collaboration with the Polish National Registry of Benign Salivary Gland Tumors. The main outcome measure was the recurrence rate in “fast” and “slow” PA subgroups. All surgical qualifications and surgeries were performed by two experienced surgeons.

Results

Slow PAs, compared to fast PAs, presented in older patients (53.25 ± 15.29 versus 47.92 ± 13.44 years). Multifactor logistic regression analysis with recurrence (yes/no) as the outcome variable, fast/slow as the predictor variable and age, gender, margin, FN status as covariates showed that fast PAs were significantly predicting recurrence vs. slow PAs (p = 0.035). Fast PAs were increasing the risk of PAs 10-fold vs. slow PAs, exp β = 10.20, CI₉₅ [1.66; 197.87]. The variables impacting relapse were recent accelerated growth of the tumor OR = 3.35 (SE = 0.56), p = 0.030, positive margins OR = 7.18 (SE = 0.57), p < 0.001, incomplete or bare capsule OR = 9.91 (SE = 0.53), p = 0.001 and location III OR = 3.12 (SE = 0.53), p = 0.033. In the multivariate model only positive margin was selected as the best predictor of relapse, OR = 5.01 (SE = 0.60), p = 0.007.

Conclusions

The simple clinical aspect of slow or fast PA progression is of great practical importance and can constitute a surrogate of the final histopathological information that is derived from the surgical specimen. The slow or fast nature of the PA to some extent indicates prognostic features such as recurrence risk. This finding requires correlation with histological and molecular features in further stages of research.

Risk factors for subsequent recurrence after surgical treatment of recurrent pleomorphic adenoma of the parotid gland

BACKGROUND

Recurrent pleomorphic adenoma (PA) can be a lifelong disease, and rates of subsequent recurrence are high.

METHODS

Patients between 2000 and 2015 were identified. Primary outcome was subsequent recurrence after surgical salvage.

RESULTS

Twenty-seven of 84 patients developed a subsequent recurrence. Risk factors for subsequent recurrence included a higher number of previous recurrences (P < .01), worse preoperative facial nerve function (P < .01), and deep parotid lesion(s) (P < .01). Interval since last surgery was protective (P < .01), specifically >10 years since last surgery (P < .01). For patients with a >10-year interval since their last surgery, the subsequent recurrence-free rate at 10 years follow-up was 80.2% vs 31.8%.

CONCLUSIONS

For patients presenting with a >10-year interval since their last surgery, subsequent recurrence rates are low, which may allow for as needed surveillance recommendations. For patients presenting with recurrent PA and ≤10 years since their last surgery, a closer surveillance is warranted.

Risk factors for carcinoma ex pleomorphic adenoma in patients presenting with recurrence after resection of pleomorphic adenoma

BACKGROUND

In patients presenting with recurrent pleomorphic adenoma (rPA), clinical evaluation can fail to recognize carcinoma ex PA (cxPA). We aim to identify the risk factors for cxPA.

METHODS

This is a single institution retrospective case-control study from 2000 to 2015. CxPA was diagnosed based on surgical pathology. Demographics, clinical, and social histories were collected.

RESULTS

A number of 13/106 (12.3%) patients were diagnosed with cxPA, of which only 4/13 (31%) had clinical features suspicious for malignancy. Compared to benign rPA, factors associated with cxPA included age >50 (odds ratio [OR] 6.67, 95% confidence interval [CI]: 1.71-25.98, P < .01), >10 pack-years of smoking history (OR 3.36, 95% CI: 1.01-11.14, P = .04), and the largest tumor being >2 cm on pathology (OR 4.42, 95% CI: 1.14-17.10, P = .03).

CONCLUSIONS

In patients presenting with rPA, risk factors for malignant transformation include age >50, significant smoking history, and tumors larger than 2 cm. Clinical signs of malignancy such as rapid growth or pain are not always present.