Abstract
Objective:To explore the clinical manifestations of IgG4-related diseases（IgG4-RD） complicated with moderately differentiated adenosquamous carcinoma of the parotid gland, the diagnostic criteria for IgG4-related diseases and parotid malignant tumors, treatment regimens, and the application of fine-needle aspiration in disease diagnosis, so as to reduce clinical misdiagnosis and missed diagnosis. Methods:A retrospective analysis was conducted on the case data of a patient with IgG4-related diseases（IgG4-RD） complicated with moderately differentiated adenosquamous carcinoma of the parotid gland admitted to our department in March 2024. The clinical characteristics, imaging findings, preoperative puncture results, and postoperative pathological features were analyzed, and relevant literatures on both diseases were reviewed and summarized. Results:The elderly male patient was admitted due to "a mass in the parotid area in front of the right ear for more than 3 months". Through clinical examination, imaging examination, laboratory examination, and preoperative needle biopsy, the diagnosis of "right parotid moderately differentiated adenosquamous carcinoma complicated with IgG4-related disease" was considered. It was also considered that IgG4-related disease did not involve other organs before surgery, so no systemic hormone therapy was given before or after surgery. After surgery combined with postoperative radiotherapy, follow-up showed that neither the parotid tumor nor IgG4-related disease recurred. Conclusion:"IgG4-related disease complicated with moderately differentiated adenosquamous carcinoma"is a rare clinical disease. Both lack typical clinical manifestations and specific imaging features, and the diagnosis is mostly unclear before surgery. Pathological examination is of great significance in the diagnosis of the disease, while fine-needle aspiration has limited value in the diagnosis, which should attract the attention of clinicians. In addition, for patients with both diseases, individualized treatment plans should be formulated.