Introduction
Although squamous cell carcinoma (SCC) is the most frequent malignancy of the external auditory canal, it is rare, with a prevalence of 1–6 persons per million.Reference Barrs1 Bilateral concomitant squamous cell carcinoma is rarer yet, with only 16 cases known to us that have been reported in the English language literature.Reference Nishio, Okazaki, Wada, Tsuzuki, Kambe and Fujimoto2 Three of these cases were radiotherapy related. Here we report the history and management of a patient presenting with bilateral radiation-related external auditory canal SCC.
Case report
In 2008, a 33-year-old woman with dialysis-dependent chronic renal failure was diagnosed with Epstein Barr positive nasopharyngeal carcinoma and bilateral metastatic cervical lymphadenopathy. She was treated with concurrent radiotherapy total dose of 70 Gray (Gy) concurrently with six cycles of weekly cisplatin. Metastatic bone disease was identified within a year of completing treatment. She then received four cycles of gemcitabine chemotherapy, and no radiation. At completion, she was disease free. Annual follow-up positron emission tomography (PET) scans were scheduled. At age 41, she underwent donor renal transplantation, with basiliximab and steroid immunosuppression induction. She is maintained on tacrolimus.
In 2022 at age 47 years, her annual PET scan demonstrated increased uptake in the right external auditory canal (EAC) (Figure 1). She was referred to an otologist who elicited a six-month history of bilateral intermittent otorrhea. She denied otalgia, hearing loss, tinnitus, or vertigo. Right otomicroscopy revealed a fleshy polypoid friable non-tender mass arising from the bony floor of the external auditory canal, adjacent to the tympanic membrane and obstructing 50 per cent of the canal lumen. The left external auditory canal demonstrated a similar but smaller lesion arising from the anterior roof of the bony canal adjacent to the tympanic membrane (Figure 2). Biopsies were consistent with p53-positive bilateral external auditory canal SCC. An initial right lateral petrosectomy and external auditory canal closure were performed. Hearing was rehabilitated with a right bone-conduction hearing aid on a head band. Four months later left external auditory canal sleeve resection and partial lateral petrosectomy with temporalis fascia free graft tympanic membrane and ear-canal lining reconstruction were performed to preserve adequate left ear hearing. Post-operatively the patient reported dysgeusia, indicative of bilateral chorda tympani sacrifices and remains disease free on her six-month post-op PET-computed tomography scan. The operative areas healed well and remained healthy except for left myringitis, which has since resolved.
Figure 1. Axial PET image of bilateral temporal bones. Increased uptake in the right external auditory canal can be seen (arrow).
Figure 2. Endoscopic image of the left external auditory canal illustrating a fleshy polypoid mass arising from the roof of the bony canal (arrow).
Discussion
The pinna is the ear site prone to bilateral SCC secondary to solar radiation in outdoor workers, however the external auditory canal is not so affected as it is shielded from sunlight.Reference Polefka, Meyer, Agin and Bianchini3
The three previous cases of radiotherapy-attributed bilateral external auditory canal SCC report initial radiotherapy to treat nasopharyngeal carcinoma, pituitary adenoma, and maxillary cancer on average 21.3 ± 7.8 years before the diagnosis of external auditory canal SCC.Reference Nishio, Okazaki, Wada, Tsuzuki, Kambe and Fujimoto2 Most radiotherapy associated second malignancies occurs within the high dose volume. Our patient was treated using intensity modulated radiotherapy, meaning that these two new cancer sites, which were over 1.5 cm away from the target volume, received only 65 per cent of the treatment dose (45 Gy). This suggests that the external auditory canals were at a lower risk of second malignancy than the nasopharynx.Reference Dracham, Shankar and Madan4 However, lower immune surveillance related to kidney transplant immunosuppression maintenance increased her susceptibility to developing cancer.Reference Tam, Yao, Amit, Gajera, Luo and Treistman5 This may account for the relative speed 14 years post radiotherapy and young age at which our patient developed bilateral p53-positive external auditory canal SCC. The other bilateral external auditory canal SCC cases presented on average at 58.6 ± 14.2 years of age.
This case also demonstrates the benefit of ongoing clinical surveillance post radiation. Due to her increased risk of second malignancy, she underwent annual PET screening, which only detected a lesion in the right ear canal. This triggered referral to an otologist who identified bilateral disease. Early detection of bilateral external auditory canal SCC allowed selection of a more conservative surgical approach to retain adequate hearing in her left ear. The patient reported intermittent otorrhea in the six months leading up to the positive scan, and if this was previously highlighted as a red flag symptom requiring an otology referral it is possible that the carcinomas may have been detected even earlier and would have further improved the patient’s hearing outcome.
Bilateral external auditory canal SCC is a rare clinical presentation. Previous radiotherapy for the treatment of a head and neck primary tumour, as well as immunosuppression appear to have played a role in our patient’s development of bilateral external auditory canal SCC. Long-term post-radiation surveillance with regular PET scans is recommended especially in young patients who are immunocompromised.
• External auditory canal squamous cell carcinoma (SCC) is a rare pathology, with bilateral concomitant cases being even more rare
• Previous cases have reported bilateral external auditory canal SCC in patients with a history of head and neck radiotherapy, suggesting radiotherapy played a role in the simultaneous development of these neoplasms
• This is the first case of an immunosuppressed patient developing bilateral external auditory canal SCC known to us
• The case was managed successfully using a purely surgical approach
• Yearly follow-up positron emission tomography scans are a useful modality for the early identification of secondary neoplasms in the head when a patient has a history of radiotherapy
• Early identification of external auditory canal SCC can allow for less radical and/or purely surgical treatment plans, which can improve preservation of hearing and prevent unnecessary radiation exposure for the patient
Author contributions
Cole Needham: literature search, initial draft, editing; Jonn Wu: data acquisition and interpretation, editing; Desmond A. Nunez: conceptualization, study supervision, secured patient consent, acquired data, editing.
Funding
None declared.
Competing interests
None declared.
Ethical approval
This case report is exempt from ethical approval based on TCPS(2022) Article 2.5.
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