Carcinoma ex-pleomorphic adenoma derived from recurrent pleomorphic adenoma shows important difference by array CGH compared to recurrent pleomorphic adenoma without malignant transformation

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.

Carcinoma Ex Pleomorphic Adenomas: An Institutional Experience and Literature Review

OBJECTIVES

To provide an institutional experience with cases diagnosed as carcinoma ex pleomorphic adenoma (CXPA), including the cytologic and histologic findings and clinical follow-up, followed by a comparison to the experience documented in the literature.

METHODS

We identified cases of CXPA diagnosed at our institution from 2011 to 2021 and reviewed the cytologic and histologic diagnoses, as well as the treatment and clinical outcomes. Additionally, a literature review of the English literature was performed on CXPAs from 2011 to 2021.

RESULTS

Forty-one cases of CXPA were identified, with the majority subclassified as adenocarcinoma, not otherwise specified. Five tumors underwent cytogenetic studies and five underwent molecular studies. To date, 36 patients are alive, 8 of whom experienced locoregional recurrence or distant metastasis.

CONCLUSIONS

Our institutional experience was comparable to that reported in the literature. Further studies are required to inquire about the role of molecular profiles of CXPAs in clinical risk assessment.

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.

Extracapsular Dissection for Small Benign Tumors of Parotid Gland: A Case Report on Contemporary Technique

Salivary gland tumor looms as painless enlarging mass which may embrace in both major or minor glands. Pleomorphic adenoma (PA) accord about 40-70% of all salivary gland tumors, where Warthin tumor, basal cell adenoma (BCA), adenoid cystic carcinoma (ACC), and sebaceous tumors have a strong predilection for major salivary gland. However, polymorphous low-grade adenocarcinoma (PLGA) has a marked predilection for the minor salivary gland. We present a case of PA in a 26-year-old male patient that has been successfully managed by extracapsular dissection (ECD) without any post-operative complications.

Somatic copy number alterations in pleomorphic adenoma and recurrent pleomorphic adenoma

OBJECTIVE

As the genetic changes in recurrent pleomorphic adenoma (RPA) have not yet been investigated, the aim of this study was to assess the genomic profile of somatic copy number alteration in RPA and pleomorphic adenoma (PA) by using array comparative genomic hybridization (aCGH).

STUDY DESIGN

Four cases of RPA and 13 cases of PA were evaluated by using aCGH, using a 180 K platform. Data were analyzed by using Nexus Copy Number Discovery.

RESULTS

The RPA group rarely showed any copy number alteration, except for 1 case that exhibited losses in 5 p15.33 p15.1, 5 q13.1 q35.3 and 12 q12 q13.11. The PA group also showed few copy number alterations, and the most frequent findings involved chromosomes 8: 8p21.3-p12 (gain), 8q12.1 (loss), 8p23.3-q24.3 (gain), and 8q12.1-q21.11 (gain). Genomic amplifications were revealed in the PA group, and the relevant affected genes were MAML2 and LIFR.

CONCLUSIONS

PA and RPA exhibit few somatic copy number alterations and show a similar genomic profile on aCGH.