Objective: To investigate the clinicopathological characteristics and diagnostic-therapeutic strategies of oncocytic mucoepidermoid carcinoma (OMEC) of the parotid gland, and to enhance awareness of this rare variant among clinicians and pathologists. Methods: The clinical data, imaging findings, histopathological features, immunophenotype, and molecular characteristics of two patients with parotid OMEC were retrospectively analyzed, and the relevant literature was reviewed. Results: Case 1 was a 50-year-old man who presented with a painless mass behind the right earlobe for more than 2 years. The patient underwent extended parotidectomy with preservation of the facial nerve. Histopathological examination revealed that the tumor was predominantly composed of oncocytic cells with a small proportion of mucous cells. Immunohistochemically, the tumor cells were partially positive for cytokeratin 5/6, cytokeratin 7, and P63. Special staining with alcian blue, periodic acid-Schiff, and phosphotungstic acid hematoxylin yielded positive results. The diagnosis of right parotid OMEC was established. No recurrence or metastasis was observed during a 1 year follow-up. Case 2 was a 61-year-old man with a 3-month history of a mass beneath the left ear. After partial parotidectomy at an outside institution, pathological consultation at the Stomatological Hospital of Jilin University demonstrated that the tumor consisted almost entirely of oncocytic cells, exhibited infiltrative growth, and lacked typical mucous, epidermoid, and intermediate cells. Fluorescence in situ hybridization confirmed positive mastermind-like transcriptional activator 2 (MAML2) gene rearrangement, establishing the diagnosis of left parotid OMEC. The patient subsequently underwent total parotidectomy with preservation of the facial nerve, and no recurrence was detected during a short-term 3 months follow-up. A review of the literature indicated that OMEC most commonly arises in the parotid gland and is generally a low-grade malignancy with favorable prognosis. When tumors are composed exclusively of oncocytic cells, exhibit minimal cytological atypia, and lack the classical cellular components of mucoepidermoid carcinoma, they are highly prone to misdiagnosis as oncocytoma, nodular oncocytic hyperplasia, or other benign oncocytic lesions. Accurate differential diagnosis relies on recognition of infiltrative growth patterns, supportive immunophenotypic markers (e.g., P63 positivity), and detection of characteristic MAML2 gene rearrangement. Complete surgical excision remains the treatment of choice. Conclusion OMEC dominated by oncocytic cells carries a high risk of clinical misdiagnosis. Integrating the assessment Conclusion OMEC dominated by oncocytic cells carries a high risk of clinical misdiagnosis. Integrating the assessment of infiltrative histopathological features with immunohistochemistry and molecular detection of MAML2 rearrangement is crucial for accurate diagnosis, appropriate assessment of tumor behavior, and optimal surgical decision making.

BACKGROUND: It is believed previously that hyperbaric oxygen(HBO)therapy can prevent stroke, but some scholars think HBO therapy on the contrary can induce stroke although its pathogen and prevention are unclear.OBJECTIVE: To study the reason of cerebral thrombosis induced by HBO and the preventive effects of the medicine.DESIGN: A retrospective study based on patients as subjects.SETTING: Department of HBO in a military area command hospital ofChinese PLA.PARTICIPANTS: Totally 192 hospitalized patients receiving HBO therapy in Guangzhou General Hospital of Guangzhou Military Area Command of Chinese PLA were selected, in which there were 127 males and 65 females aged between 9 and 78 years old. A total of 6 cases including 3 male and 3 female cases aged between 51 and 76 years old developed cerebral thrombosis during therapy.METHODS: The background factors of 192 patients who received HBO therapy and the included 6 cerebral thrombosis cases were analyzed. Totally preventive effects of the medicine on a cluster level of different risk factor. Three groups of patients received different interventions under the prerequisites of routine medications including blood-activating and stasis-eliminating, neurotrophy, and vasodilator patients of nitric ether group received oral administration of isosorbide dinitrate or glycerin trinitrate; patients of calcium antagonist group received oral administration of Sibelium or Novarsc; and patients of no specific medication group did not receive any preventive medicine.MAIN OUTCOME MEASURES: Patients' symptoms, physical signs andhead CT or MRI.RESULTS: The risk factor of cerebral thrombosis induced by HBO was the basic disease of hyperlipidemia or hypertension, etc. A total of 115 cases had the cluster with less than 4 risk factors and none of them developed thrombosis. A total of 31 cases had the cluster with 4 or more than 4 risk factors and 6 of them developed thrombosis with greatly increased morbidity. Above the level of 4 risk factors, nitrate ether had effective preventive effect(0/13) while there was 33.3% of the patients(5/15) in calcium antagonist group developed thrombosis, and the difference between the above two groups was significant( P ＜ 0.05).CONCLUSION: The cluster level of risk factors has close relationship with the probability of thrombosis induced by HBO. Nitrate ether has significant preventive effects.