Malignant Myoepithelioma of the External Auditory Canal – a Rare Case Report with Literature Review and Clinical Importance of Foramen of Huschke

Abstract

Background: Myoepitheliomas are rare tumors, mostly arising from the salivary glands. Malignant myoepitheliomas of the ear have rarely been reported. This manuscript reports myoepithelial carcinoma of the external ear canal (EAC) spreading to the infratemporal fossa. A clinician must also be aware of anatomical variation of the bony EAC wall, such as the foramen of Huschke. This rare defect may be a pathway for spreading pathologies between these two anatomical regions. Case report: We present a case of osteoma-like stenosis of the EAC, which turned out to be an extremely rare malignant tumor. The preoperative MRI and PET/CT revealed that two parts of the tumor communicated through a defect in the antero-inferior portion of the bony ear canal. No distant metastases were detected. Subsequently, the tumor was resected from the ear canal and from the infratemporal fossa en bloc. Perioperatively the defect in the EAC wall was suspected of the foramen of Huschke. After the surgery, the older scans of the patient from the past showed no presence of a congenital EAC wall defect. Therefore, the authors concluded that the tumor aggressively grew through the bone due to its biological nature. This case report is aimed to improve the clinical knowledge of possible unusual communication between EAC and infratemporal fossa. Conclusion This is only the fourth reported case describing malignant myoepithelioma of the ear, to date. The purpose of this article is to point out the clinical importance of proper diagnostic management of ear canal masses, considering their location and possible invasion of adjacent structures. The manuscript also highlights the clinical importance and development of the foramen of Huschke.