Metastatic Renal Cell Carcinoma Presenting in the External Auditory Canal

Abstract

A 57-year-old male previously in good health presented to his primary care physician with sudden onset of left-sided subjective hearing loss and aural fullness. Examination revealed a small polypoid, friable mass in the left external auditory canal. Excisional biopsy findings were consistent with metastatic renal cell carcinoma, and the patient subsequently was referred to our institution, where further diagnostic workup, including renal biopsy, confirmed the diagnosis. Physical examination at that time revealed regrowth of the aural mass, which now completely occluded the external auditory canal and protruded from the meatus (Fig 1). Audiogram revealed a mixed profound hearing loss in the left ear, and MRI of the internal auditory canals and brain demonstrated multiple intracranial metastasis with erosion of middle-ear structures. Metastic renal cell carcinoma protruding from external auditory canal Metastatic tumors to the external auditory canal are rare. Renal cell carcinoma is the 3rd most common metastatic lesion in the head and neck after breast and lungs.1 Because of the erratic nature and growth of this entity, it often is the signs and symptoms of metastasis that alert to the presence of disease. Up to 16% of hypernephromas will ultimately spread to the head and neck, with 8% of these resulting in the onset of symptoms.2 Because of its apparent ability to bypass normal capillary filtration mechanisms, renal cell carcinoma metastasis may travel directly to the head and neck via Batson's plexus. This valveless epidural and vertebral venous plexus allows the disease to spread unimpeded to multiple thoracic vessels as well as the vena cava.3 Although the classic presenting triad includes gross hematuria, flank pain, and palpable abdominal mass, only a minority of patients will present with all 3. More commonly seen is painless gross hematuria, alone or in conjunction with the various signs and symptoms of metastatic spread.2 Spread to the ear may present with hearing loss, pain, otorrhea, bleeding, facial nerve paralysis, or a mass in the ear canal.4 As demonstrated in our patient, these masses may present as benign-appearing aural polyps; thus, clinical suspicion is key in early diagnosis. Histologically, renal cell carcinoma appears as clear cells arising from the proximal tubular apparatus; however, its appearance may be confused with other neoplastic processes.2 Immunohistochemistry is valuable in the differentiation from similar-appearing neuroendocrine processes. Also greatly used during the diagnostic evaluation are CT and MRI. Renal cell carcinoma will appear as an enhancing soft-tissue mass on CT with reliable delineation of bony erosion, whereas MRI may offer more precise soft-tissue margins.1 Utilization of all diagnostic modalities must be employed because of the extremely poor prognosis for metastatic renal cell carcinoma, with <10% 5-year survival.5 Earlier diagnosis and treatment raises this percentage; therefore, metastatic lesions always must be on one's differential for head and neck masses.