IgG4-related disease on parotid gland mimicking pleomorphic adenoma: Report of a case

Han, Suah; Leem, Dae Ho; Ku, Jeong-Kui; Chae, Jong Seong

doi:2026.64.5.151

J Korean Dent Assoc > Volume 64(5); 2026 > Article

Case Report

Journal of Korean Dental Association 2026;64(5):151-156.
DOI: https://doi.org/10.22974/jkda.2026.64.5.001 Published online May 29, 2026.

IgG4-related disease on parotid gland mimicking pleomorphic adenoma: Report of a case

Suah Han¹

, Dae Ho Leem¹

, Jeong-Kui Ku^1,2

, Jong Seong Chae¹

¹Department of Oral and Maxillofacial Surgery, School of Dentistry, Jeonbuk National University, Jeonju, Koreaa
²Department of Oral and Maxillofacial Surgery, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea

Correspondence: Dae Ho Leem, Tel: +82-63-250-2113,
Email: idisho@jbnu.ac.kr

Received: 29 December 2025 • Revised: 23 March 2026 • Accepted: 13 April 2026

Abstract

IgG4-related disease (IgG4-RD) is a rare immune-mediated inflammatory disorder that can involve salivary glands and mimic benign tumors radiologically. This report presents a case of IgG4-RD of the parotid gland initially suspected as pleomorphic adenoma. A 66-year-old female patient presented with swelling and pain in the left temporomandibular joint region. Magnetic resonance image and ultrasonography-guided fine needle aspiration suggested a benign cystic tumor, and both parotid lesions were initially suspected to be bilateral pleomorphic adenomas. Excisional biopsy was performed on the larger lesion in the left parotid gland. Histopathological examination revealed a lymphoepithelial cyst with storiform fibrosis and dense infiltration of IgG4-positive plasma cells (72/HPF). Serum IgG4 level was elevated (141 mg/dL), satisfying the diagnostic criteria for IgG4-RD. The patient was referred to rheumatology for systemic evaluation and steroid therapy was considered. This report highlights the diagnostic challenge of differentiating IgG4-RD from benign parotid tumors.

Key Words: Immunoglobulin G4-Related Disease; Adenoma, Pleomorphic; Parotid Gland; Salivary Gland Neoplasms; Diagnosis, Differential