Ten patients with high-grade transformation of acinic cell carcinomas

Acinic cell Carcinoma with high-grade Squamoglandular and Chondrosarcomatous Transformation Mimicking 'Carcinosarcoma ex-pleomorphic Adenoma': A Wrinkle in the Proposed Nomenclature Revision for Sarcomatoid Salivary Gland Neoplasms

While acinic cell carcinoma (AciCC) can undergo high-grade transformation (HGT) to high-grade adenocarcinoma or poorly differentiated carcinoma, other morphologies such as spindle cell/sarcomatoid carcinoma are rare and not well-characterized. We herein report a novel case of AciCC with squamoglandular and chondrosarcomatous HGT mimicking a so-called 'carcinosarcoma ex-pleomorphic adenoma'. The patient is an 81-year-old male with a two-month history of neck swelling and referred otalgia who presented with a left parapharyngeal space mass extending into retropharyngeal space and pterygoid muscles. On resection, the tumor showed considerable morphologic diversity with high-grade serous and mucous acinar components as well as cribriform to solid apocrine-like components with comedonecrosis and squamous differentiation, all of which were embedded in a chondromyxoid background ranging from paucicellular and bland to a high-grade chondrosarcoma/pleomorphic sarcoma-like appearance. Only a minor conventional AciCC component was noted. Immunostains were negative for AR and only focally positive for GCDFP-15 arguing against a true apocrine phenotype, while PLAG1 and HMGA2 were negative arguing against an antecedent pleomorphic adenoma. On the other hand, SOX-10, DOG-1 and PAS after diastase highlighted serous acinar differentiation, and mucicarmine, and NKX3.1 highlighted mucous acinar differentiation. NR4A3 immunohistochemical staining and NR4A3 fluorescence in situ hybridization were positive in the carcinomatous and sarcomatoid components while sequencing analysis of both components revealed identical alterations involving TP53, PIK3CB, ARID1A, and STK11. This unique case warrants caution in designating all salivary sarcomatoid carcinomas with heterologous elements as part of the 'carcinoma ex-pleomorphic adenoma' family.

A Retrospective Multicenter Italian Analysis of Epidemiological, Clinical and Histopathological Features in a Sample of Patients with Acinic Cell Carcinoma of the Parotid Gland

BACKGROUND

The acinic cell carcinoma (AciCC) of the parotid gland is a rare tumor with an indolent behavior; however, a subgroup of this tumor presents an aggressive behavior with a tendency to recur. The aim of this multicenter study was to identify and stratify those patients with AciCC at high risk of tumor recurrence.

METHODS

A retrospective study was carried out involving 77 patients treated with surgery between January 2000 and September 2022, in different Italian referral centers. Data about tumor characteristics and its recurrence were collected. The histological specimens and slides were independently reviewed by a senior pathologist coordinator (L.C.) and the institution's local head and neck pathologist.

RESULTS

The patients' age average was 53.6 years, with a female prevalence in the group. The mean follow-up was 67.4 months (1-258, SD 59.39). The five-year overall survival (OS) was 83.2%. The 5-year disease-free survival (DFS) was 60% (95% CI 58.2-61.7). A high incidence of necrosis, extraglandular spread, lymphovascular invasion (LVI), atypical mitosis, and cellular pleomorphism was observed in the high-risk tumors compared to the low-risk ones.

CONCLUSION

AciCC generally had an indolent behavior, optimal OS, DFS with few cervical node metastases, and rare distant relapses. This multicenter retrospective case series provides evidence of the need for clinical-epidemiological-histological stratification for patients at risk of poor outcomes. Our results suggest that the correct definition of high-risk AciCC should include tumor size, the presence of necrosis, extraglandular spread, LVI, atypical mitosis, and cellular pleomorphism.

Loss of CDKN2A/B is a Molecular Marker of High-grade Histology and is Associated with Aggressive Behavior in Acinic Cell Carcinoma

Acinic cell carcinoma (AciCC) is a rare salivary gland cancer with excellent prognosis in most cases. However, a subset of patients will develop distant metastasis and die of disease. Recently, a 2-tiered grading scheme in AciCC was proposed to recognize patients at risk of poor outcome. We performed a genetic analysis of AciCC to explore the underlying molecular correlates of the tumor grade and examined programmed death ligand 1 (PD-L1) expression to identify potential candidates for immunotherapy. A retrospective cohort of 55 patients included 34 high-grade (HG) and 21 low-grade AciCCs. Forty-three cases were subjected to targeted exome sequencing by Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets. PD-L1 immunohistochemistry was performed in 33 cases. Tumor mutation burden was low with a median of 1 and 2 mutations in low-grade and HG AciCCs, respectively. CDKN2A/B was the most frequently altered gene, and loss-of-function mutations were found only in HG but not in low-grade AciCCs (18/31 [58.1%] vs 0/12 [0%], P < .001). CDKN2A/B alterations were significantly associated with distant metastasis, which occurred in 16/18 (88.9%) CDKN2A/B mutants versus 11/25 (44%) wild-type cases (P = .004, Fisher exact test). Sequential profiling of multiple temporally distant samples from the same patient demonstrated intratumor heterogeneity, including the detection of CDKN2A/B deletion in the second, in HG metastasis only. ATM and PTEN mutations were detected in 6/31 (19.4%) and 5/31 (16.1%); ARID2, BIRC3, and FBXW7 mutations each in 4/31 (12.9%); and TP53, MTAP, and FAT1 each in 3/31 (9.7%) HG AciCC. PD-L1-positive labeling was more common in HG AciCC (9/17, 52.9% vs 3/16, 18.9%, P = .071). CDKN2A/B mutations in AciCC represent a molecular marker of HG histology and disease progression, providing a rationale for further studies to determine their prognostic and therapeutic significance in this salivary gland cancer. AciCC with ATM mutations may be amenable to targeted therapy. Immunotherapy can be considered to be a treatment option for a subset of patients with AciCC.

Head and Neck Acinic Cell Carcinoma: A New Grading System Proposal and Diagnostic Utility of NR4A3 Immunohistochemistry

Acinic cell carcinoma (AciCC) is traditionally considered as a low-grade salivary gland carcinoma. However, a subset demonstrates high-grade features with a higher mortality rate and distant metastasis. In this large retrospective study of 117 cases, we aimed to establish a histologic grading scheme for AciCC. Adverse independent prognostic factors identified on the multivariate analysis included older age, tumor necrosis, nuclear anaplasia, lymphovascular invasion, absence of tumor-associated lymphoid stroma, and high American Joint Committee on Cancer (AJCC) pT and pN stages. A 3-tiered grading scheme using 4 pathologic parameters (mitotic index, necrosis, tumor border, and fibrosis at the frankly invasive front) was subsequently applied. Compared with low/intermediate-grade, high-grade AciCC defined as a mitotic index ≥5/10 HPFs and/or necrosis was an independently adverse prognostic factor. The 5-year overall survival was 50% in high-grade AciCCs, and 100% in low-grade or intermediate-grade AciCCs. Compared with low-grade or intermediate-grade AciCC, high-grade tumors were associated with older age, larger tumor size, focal rather than diffuse zymogen granules, solid architecture, infiltrative tumor border, fibrosis at the frankly invasive front, lymphovascular invasion, perineural invasion, positive margin, high pT, and pN stages. NR4A3 was a highly sensitive and specific immunohistochemical stain for diagnosing AciCC with a sensitivity and specificity of 96% and 93%, respectively. In conclusion, although we proposed a 2-tiered grading system for AciCC with high-grade tumors defined by a mitotic count ≥5/10 HPFs and/or necrosis, more studies are needed to assess the prognostic value of intermediate grade. NR4A3 immunohistochemical stain is a useful diagnostic marker for AciCC.

Prognostic factors in acinic cell carcinoma of the head and neck: The Amsterdam experience

INTRODUCTION

The aim was to analyse prognosticators in acinic cell carcinoma (AciCC) in two head and neck referral centers in Amsterdam, the Netherlands.

MATERIALS AND METHODS

Eighty- nine cases of AciCC treated between 1979 and 2016 were retrospectively reviewed. Five, - 10 -and 20- year estimates of survival were executed as well as univariate analysis of prognosticators.

RESULTS

The majority of AciCC were T1-T2; 89%. Two percent had nodal disease (2%). The most affected organ was the parotid gland (84%) with a female preponderance (67%). Mean age was 52 years with most cases diagnosed in the fourth to sixth decade. The majority of patients received adjuvant radiotherapy. Elective neck dissection (END) in the N0 neck showed no metastases. High grade transformation (HGT) was found in 21% of cases. Median follow up was 101.9 months. Median time to recurrence was 26 months. Nine patients developed distant metastases (DM) of whom 6 had HGT-AciCC. Median survival with DM was 7 months. Five,- ten -and twenty- year estimates were 84%, 81% and 81% for recurrence free survival respectively. Negative clinical features were advanced stage disease and tumour size > 2.6 cm. Negative histological features were a high mitotic rate, HGT, close and involved surgical margins and necrosis.

CONCLUSION

AciCC- HGT excluded- of the head and neck has an excellent prognosis and shows acceptable long term results. END can be considered as part of the standard treatment due to the relative high incidence of HGT- AciCC and low accuracy of cytology.

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.

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.

Atypical Presentation of Mammary Analogue Secretory Carcinoma of the Lip

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a rare tumor that was first described by Skalova et al in 2010, and since then, only a few hundred cases have been reported in the literature. Prior to Skalova's report, MASC was histologically misclassified as acinic cell carcinoma (ACC), pleomorphic adenoma, mucoepidermoid carcinoma, or adenocarcinoma, not otherwise specified. Mammary analogue secretory carcinoma has a low incidence rate overall, accounting for less than 0.3% of all salivary gland tumors. Histopathologic and cytogenic analysis of MASC is identical to secretory carcinoma of the breast, leading to the proposed name by Skalova. The purpose of this case presentation is to describe an atypical presentation of MASC, to compare this case with the classic description of MASC, and to contrast the various features of MASC to ACC in order to improve the accuracy of future diagnoses and help guide treatment.