Neuroendocrine Tumor of the Middle Ear.

Middle ear adenomatous neuroendocrine tumors (MEANT) are rare neoplasms frequently misdiagnosed due to their nonspecific clinical presentations. We present the case of a 25-year-old woman who reported a 2-month history of tinnitus, dizziness, and left-sided conductive hearing loss. Otoendoscopy and computed tomography revealed a well-circumscribed, vascular soft-tissue mass in the epitympanum extending to the mastoid antrum, which was subsequently managed with complete transcanal endoscopic excision. Histopathological evaluation confirmed a well-differentiated neuroendocrine tumor. A definitive diagnosis was established through comprehensive immunohistochemical profiling, demonstrating positive staining for INSM-1 and chromogranin-A, alongside a low Ki-67 proliferation index of less than 3%. Following the procedure, the patient exhibited stable hearing and no clinical or radiologic evidence of tumor recurrence over an 8-year follow-up period. Ultimately, this case highlights the critical importance of utilizing the 2022 WHO classification and immunohistochemical markers to accurately diagnose MEANT. Furthermore, it underscores a vital clinical caveat: while complete surgical excision is the definitive treatment, the tumor's established propensity for delayed recurrence mandates indefinite, long-term clinical and radiologic surveillance.