Sporadic Mixed Heterotopic Tissue Choristoma of the Middle Ear in an Adolescent Female: A Rare Case Report.

Choristomas are rare benign developmental lesions composed of histologically normal tissue located in an abnormal (ectopic) anatomical site. Their occurrence in the middle ear is uncommon and may mimic more common pathologies such as chronic otitis media or cholesteatoma, often leading to diagnostic challenges. We report a 16-year-old female who presented with chronic left ear discharge and hearing loss for 8 years. Examination revealed bilateral grade I microtia with a narrow external auditory canal. Pure tone audiometry showed bilateral conductive hearing loss, and high-resolution computed tomography demonstrated a soft-tissue mass in the left middle ear and mastoid with ossicular erosion. A transmeatal exploratory tympanotomy was performed, revealing an encapsulated small brown soft-tissue mass limited to the tympanic cavity complete excision done. Histopathological examination confirmed a mixed heterotopic tissue choristoma composed of skin, adnexal structures, fibroadipose tissue, muscle, cartilage, and salivary gland elements. The postoperative course was uneventful, with hearing improvement and no recurrence at 6-month follow-up. This case highlights the importance of considering middle-ear choristoma in the differential diagnosis of chronic otorrhea and conductive hearing loss to avoid misdiagnosis and unnecessary aggressive treatment.