A case report of misdiagnosed adenoid cystic carcinoma of the parotid gland on ultrasound - imaging-pathological correlation and diagnostic implications

Sep 29, 2026

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A 46-year-old woman presented with a painless, long-standing left parotid mass whose ultrasound appearance suggested a benign pleomorphic adenoma: well-defined margins, homogeneous hypoechogenic solid echogenicity, posterior acoustic enhancement, and sparse punctate/linear vascular signals. Enhanced CT showed heterogeneously enhancing disease without invasion. Postoperative pathology confirmed adenoid cystic carcinoma with cribriform/trabecular architecture and supportive markers (SOX10/p63-positive, Ki-67 3%, MYB::NFIB fusion-negative). The case emphasizes benign-mimicking ultrasound traits and the need for multimodal imaging integration and biomarkers to improve diagnostic accuracy and follow-up management.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages7

Reading Time18 min

AccessFree to download

Introduction

Background and known clinical challenges

Case Description

Clinical presentation and imaging findings

Pathology confirmation and treatment

Conclusions

Diagnostic implications of benign-mimicking features

Highlight Box

Key findings

What is known and what is new

Implication and what should change now

A case report of misdiagnosed adenoid cystic carcinoma of the parotid gland on ultrasound: imaging-pathological correlation and diagnostic implications Xia Zeng1,2, Heli Duan3, Xiaojuan Ma1 1Department of Ultrasound, West China Hospital, Sichuan University, Chengdu, China; 2Department of Ultrasound, Chengdu Shang Jin Nan Fu Hospital, Chengdu, China; 3Department of Ultrasound, Chengdu Integrated TCM & Western Medicine Hospital, Chengdu, China Contributions: (I) Conception and design: X Zeng, H Duan; (II) Administrative support: X Ma; (III) Provision of study materials or patients: X Ma, X Zeng; (IV) Collection and assembly of data: X Ma, X Zeng; (V) Data analysis and interpretation: X Zeng, H Duan; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors. Correspondence to: Xiaojuan Ma, MD. Department of Ultrasound, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Wuhou District, Chengdu 610041, [China. Email: xiaojuanma@126.com](China. Email: xiaojuanma@126.com). Background: Adenoid cystic carcinoma (ACC) of the parotid gland is a rare malignant salivary tumor with aggressive biological behavior, including perineural invasion and delayed metastasis. Despite an 85% 5-year survival rate, long-term prognosis declines to approximately 30% . Preoperative imaging diagnosis remains challenging due to ACC’s heterogeneous features on ultrasound, often mimicking benign tumors like pleomorphic adenoma, leading to misdiagnosis. The clinical value of multimodal imaging integration for ACC is underexplored. Case Description: A 46-year-old female presented with a painless left parotid mass persisting for >1 year. Initial ultrasound revealed a well-defined, hypoechoic solid nodule (measuring 2.5 cm × 2.0 cm × 2.0 cm on sonography) with homogeneous echogenicity, posterior acoustic enhancement, and sparse punctate/linear vascular signals, suggestive of pleomorphic adenoma. Enhanced computed tomography (CT) showed a heterogeneously enhancing mass (+45 HU arterial phase) without invasion. Postoperative pathology confirmed ACC (cribriform/trabecular patterns; SOX10/p63-positive; Ki-67 3%; MYB::NFIB fusion-negative) . The patient underwent parotidectomy with facial nerve preservation and adjuvant radiotherapy, with no recurrence at 6-month magnetic resonance imaging (MRI) follow-up. Conclusions: This case highlights ACC’s propensity for “benign-mimicking” sonographic features (welldefined margins, posterior enhancement, hypovascularity), contributing to misdiagnosis. It underscores that integrating elastography (for assessing stiffness), contrast-enhanced ultrasound (for evaluating washout patterns), CT/MRI (for detecting suspicious perineural spread), and molecular biomarkers (e.g., low Ki-67) is crucial to improving diagnostic accuracy and optimizing follow-up management for ACC. Keywords: Adenoid cystic carcinoma (ACC); parotid gland; multimodal imaging; pathological correlation; case report Submitted Aug 07, 2025. Accepted for publication Nov 04, 2025. Published online Dec 24, 2025. doi: 10.21037/gs-2025-354 View this article at: [https://dx.doi.org/10.21037/gs-2025-354](https://dx.doi.org/10.21037/gs-2025-354) © AME Publishing Company. Gland Surg 2025;14(12):2528-2534 | [https://dx.doi.org/10.21037/gs-2025-354](https://dx.doi.org/10.21037/gs-2025-354) Gland Surgery, Vol 14, No 12 December 2025 2529 Introduction Adenoid cystic carcinoma (ACC) is a rare malignant neoplasm and one of the primary malignant salivary gland tumors (1) . Although characterized by indolent growth, ACC exhibits aggressive biological behaviors, including a propensity for perineural invasion and delayed distant metastasis (2) . The 5-year survival rate may reach 85%, yet the long-term prognosis deteriorates markedly, with survival rates declining to approximately 30%(1) . Imaging serves as a cornerstone for preoperative diagnosis and staging evaluation, playing a pivotal role in surgical plann

FAQs

Why was the adenoid cystic carcinoma initially misdiagnosed on ultrasound?

The lesion showed deceptively benign ultrasound characteristics, including well-defined margins, homogeneous hypoechogenicity, posterior acoustic enhancement, and sparse vascularity, which commonly mimic pleomorphic adenoma.

What confirmed the final diagnosis after surgery?

Postoperative pathology demonstrated adenoid cystic carcinoma with cribriform/trabecular patterns and immunohistochemical and molecular findings, including SOX10/p63 positivity, Ki-67 of 3%, and MYB::NFIB fusion-negative status.

Which additional diagnostic tools are recommended to reduce misdiagnosis risk?

The report highlights integrating elastography, contrast-enhanced ultrasound (washout assessment), CT/MRI for suspected perineural spread, and molecular biomarkers to improve diagnostic accuracy and guide follow-up.

Sep 29, 2026

Uploaded by Aditya