Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature. Cancer of the External Auditory Canal External auditory canal cancer is a rare disease which presents a number of interesting problems with regards to both diagnosis and treatment. Unlike most other skin cancers, cancer of the EAC has been found to be more common in women than men. The median age of onset is 55 years. It has been estimated that EAC cancer represents between 1 in 5,000 and 1 in 20,000 ear complaints seen in a typical practice. There is generally believed to be a higher incidence in patients with preexisting ear inflammation such as otitis externa, chronic otitis media, or cholesteatoma. The most common histologic types of EAC cancer are squamous cell, basal cell, and glandular tumors including adenoid cystic, mucoepidermoid and adenocarcinoma. Other rare lesions include sarcomas, melanoma, sebaceous cell carcinoma and metastatic lesions. By far the most common of these is squamous cell carcinoma which accounts for approximately 90% of all cases. The etiology of EAC carcinoma is speculative at this time. Malignant change from chronic inflammation similar to that seen in a Marjolin's ulcer is the most frequently suggested. However, this has never been proven. Tumor spread may progress laterally to the auricle along the skin, or to the parotid through holes in the external canal cartilage known as the fissures of Santorini. Once erosion through the bony canal has occurred, spread is through the mastoid air cells tympani or medially toward the internal acoustic meatus. The facial nerve may become involved along its vertical or tympanic segment. Once tumor has involved the middle ear cleft, spread may advance via the stapedius muscle remnant, the eustachian tube, or again, via the mastoid air cells. Extensive tumor spread may lead to involvement of the carotid artery, jugular vein or other cranial nerves. The diagnosis and staging of external canal cancer are quite problematic. There is usually a delay of at least six months resulting from the rareness of the disease coupled with the similarity of its presentation with more benign diseases such as otitis externa or chronic otitis media. The common history of past otologic disease further compounds the difficulty in early detection. Early diagnosis, which is the single most important factor for eradication of disease depends on a high level of suspicion by the otolaryngologist. Non-responsiveness to topical or systemic treatment are a common clue to a malignant process. Pain, which usually indicates bony involvement, is a common symptom and should greatly heighten suspicions. Bloody otorrhea is another hallmark of malignancy, although this is a rare and relatively late finding. Diagnosis is dependent upon biopsy, and biopsy of any canal lesion which is unresponsive to routine therapy is essential. Other suggested diagnostic studies include temporal bone CT scans, and angiography if there appears to be involvement of the great vessels. Determination of the degree of spread can also be problematic. The tympanic membrane can be visualized less than 50% of the time, and, thus, involvement of the middle ear cleft may be difficult to determine. Infiltration of the parotid gland may be difficult to palpate. Finally, even modern imaging studies usually cannot differentiate between tumor foci and reactive soft tissue changes in the middle ear and mastoid. Thus the full extent of the tumor frequently cannot be determined until the time of surgery. Surgery for external canal cancer varies from a minimal "sleeve excision" of the external canal to lateral temporal bone resection to subtotal and total temporal bone resection. Lewis, along with Parsons, pioneered the concept of formal temporal bone resection in 1954 in an attempt to remove the tumor en bloc. He described subtotal temporal bone resection, with intracranial exposure, removal of the external canal, middle ear, and mastoid, along with the temporomandibular joint, parotid and root of zygoma. This technique was a significant step forward in that it offered en bloc resection of the tumor. Critics of this procedure pointed to its relatively high morbidity and relatively poor five year survival, approximately 28%. They also pointed out that the extensive resection still often cut through tumor planes. These objections led Crabtree to propose a more limited procedure consisting of en bloc resection of the external auditory postoperative radiotherapy if surgical margins were positive. This procedure provided a more limited en bloc resection of the tumor, which was acceptable for localized tumor. However, more extensive tumors which left positive surgical margins were very disappointing, and radiotherapy for residual disease was of no apparent benefit. For this reason, Kinney expanded on Crabtree's approach with a more aggressive step-wise resection of the temporal bone. He recommended en bloc resection of the external canal as described by Crabtree, with intraoperative frozen section analysis of all margins. This is followed by an aggressive piecemeal resection of any gross tumor extension in conjunction with normal tissue, until all visible and microscopic tumor is removed. In this step-wise fashion, the operative can be expanded from a minimal surgery consisting of external canal excision, to an aggressive temporal bone resection. Radiotherapy is considered to be an important adjunct to surgical therapy. Improved survival has been demonstrated when radiotherapy was administered following surgical resection with clean surgical margins. It has had no apparent benefit where histologically positive margins were left at surgery. The overall five-year survival for this disease is approximately 50%, although this prognosis is significantly effected by the extent of the lesion and by histologic type. With disease localized to the external canal, prognosis can be quite good, with five year survivals approaching 80%, while with extension into the middle ear or mastoid the prognosis drops to 25% or lower. Patients with basal cell carcinoma have an overall five year survival of almost 80%, while those with malignant salivary gland tumors have almost no chance of cure. . Case Presentation A 62-year-old white male with a 40-year history of recurrent left ear drainage, presented to his private otolaryngologist in 1992 with left ear drainage, pruritis, and hearing loss. He was treated initially with topical antibiotic drops, which had been used successfully in the past, and when his symptoms did not resolve, he was placed on oral ciprofloxacin. After four weeks of therapy, a more aggressive workup including biopsy was recommended to the patient, but he declined. He presented to the Veteran's Affairs Hospital for a second opinion. Examination revealed a firm, granular mass arising from the posterior half of the external auditory canal and occluding the tympanic membrane. The remainder of his examination was normal. Biopsy of the mass revealed well-differentiated squamous cell carcinoma. CT scanning of the temporal bone demonstrated invasion of the posterior bony canal with soft tissue changes noted in the mastoid and middle ear cleft. Audiometry revealed a severe, predominantly conductive, left-sided hearing loss with a flat tympanogram. Bibliography Conley J. Cancer of the middle ear. Ann Otol Rhinol Laryngol 1965;74:555-572. Conley J, Schuller DE. Malignancies of the ear. Laryngoscope 1976;86:1147-1163. Crabtree JA, Britton BH, Pierce MK. Carcinoma of the external auditory canal. Laryngoscope 1976;86:405-415. Fliss DM, Draus M, Tovi F. Adenoid cystic carcinoma of the external auditory canal. Ear Nose Throat J 1990;69:635-645. Gacek RR, Goodman M. Management of malignancy of the temporal bone. Laryngoscope 1977;87:1622-1634. Goldman NC. Adenoid cystic carcinoma of the external auditory canal. Otolaryngol Head Neck Surg 1992;106:214-215. Goldman NC, Hutchinson RE, Goldman MS. Metastatic renal cell carcinoma of the external auditory canal. Otolaryngol Head Neck Surg 1991;106:410-411. Goodwin WJ, Jesse RH. Malignant neoplasms of the external auditory canal and temporal bone. Arch Otolaryngol 1980;106:675-679. Johns ME, Headington JT. Squamous cell carcinoma of the external auditory canal. Arch Otolaryngol 1974;100:45-49. Kinney SE. Squamous cell carcinoma of the external auditory canal. Am J Otol 1989;10:111-116. Kinney SE, Wood BG. Malignancies of the external ear canal and temporal bone: surgical techniques and results. Laryngoscope 1987;97:158-164. Kitamura K, Asai M, Kubo T, Harii K, Hasegawa A. Mucinous carcinoma of the external auditory canal: case report. Head Neck 1990;12:417-420. Lederman M. Malignant tumors of the ear. J Laryngol Otol 1965;79:85-119. Lewis JS. Squamous carcinoma of the ear. Arch Otolaryngol 1973;97:41-42. Lewis JS. Surgical management of tumors of the middle ear and mastoid. J Laryngol Otol 1983;97:299-311. Lewis JS. Temporal bone resection. Review of 100 cases. Arch Otolaryngol Head Neck Surg 1975;101:23-25. Parsons H, Lewis JS. Subtotal resection of the temporal bone for cancer of the ear. Cancer 1954;7:995-1001. Saldanha CBR, Bennett JDC, Evans JNG, Pambakian H. Metastasis to the temporal bone, secondary to carcinoma of the bladder. J Laryngol Otol 1989;103:599-601. Shih L, Crabtree JA. Carcinoma of the external auditory canal: an update. Laryngoscope 1990;100:1215-1218. Spector JG. Management of temporal bone carcinomas: a therapeutic analysis of two groups of patients and long-term followup. Otolaryngol Head Neck Surg 1991;104:58-66. Stafford ND, Frootko NJ. Verrucous carcinoma in the external auditory canal. Am J Otol 1986;7:443-445. Stell PM. Carcinoma of the external auditory meatus and middle ear. Clin Otolaryngol 1984;9:281-299. Wang CC. Radiation therapy in the management of carcinoma of the external auditory canal, middle ear, or mastoid. Radiology 1975;116:713-715. Willging JP, Pensak ML. Temporal bone resection. 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