Abstract: Objective The aim is to explore the clinical characteristics, imaging manifestations, and surgical strategies of endoscopic combined microscopic surgery for middle ear teratoma in infants. Methods The main clinical manifestation in this paediatric patient was recurrent discharge from the ear canal. Preoperative temporal bone computed tomography(CT)revealed a soft tissue mass with bone destruction in the left external auditory canal and middle ear. The lesion extended through the Eustachian tube to the nasopharynx. Magnetic resonance imaging(MRI)showed a T1-weighted image(T1WI)iso-signal and T2-weighted image(T2WI)high signal mass with local diffusion restriction. Under general anesthesia, endoscopic and microscopic surgery were performed. A posterior auricular approach mastoid exploration was used in combination with a nasopharyngeal approach to completely remove the tumour and perform artificial ossicular chain reconstruction. During the operation, a new growth was found in the tympanic cavity, with visible hair on the surface and encapsulating the ossicular chain. Results The postoperative pathology report diagnosed the tumour as a mature teratoma. Follow-up showed that the tympanic membrane had recovered well, withno complications such as facial nerve palsy. However, hearing did not show significant improvement during the postoperative follow-up and further observation was required. A total of 16 reports(23 cases)were included in the literature review. Combined with this case, the analysis showed that: The median age at onset was 12 months(range 2 weeks-12 years), and the onset was more common in females(87.5%, 21/24); The left side was affected in 87.5%(21/24)of cases. The clinical manifestations were mainly ear discharge(87.5%), hearing loss(70.8%), and ear pain(37.5%). Some children presented with facial paralysis, postauricular redness and swelling, and nasal pharyngeal obstruction. The imaging features were as follows: CT showed slightly high-density foci in the external auditory canal, tympanic cavity, and eustachian tube accompanied by the surrounding ossicular chain. MRI mostly showed T1 iso-signal and T2 high signal. The pathological type was mainly mature teratoma.The treatment mostly adopted the microsurgical approach with tumour resection through the posterior auricular incision. In some cases,endoscopic techniques were used to remove the tumour through the eustachian tube approach. After the operation, 2 cases had recurrence and underwent reoperation, the rest had good prognosis. Conclusion Infantile middle ear teratoma exhibits characteristic clinical manifestations and imaging features. A combination of endoscopic and microscopic surgery provides good exposure of the surgical field and enables complete tumour resection. The timing of surgery for the ossicular chain still needs to be carefully considered, and the decision on ossicular chain reconstruction should be based on long-term follow-up observations.

Key words: Middle ear teratoma, Infant, Endoscopic, Microscopic, Purulent otorrhea