Imaging of carcinoma of the external auditory canal: a pictorial essay

Necrotizing Otitis Concealing Carcinomas of the External Auditory Canal

External auditory canal Carcinomas are rare and aggressive tumors and their prognosis depends on early diagnosis. Their clinical similarity to necrotizing otitis is a source of error and therefore of diagnostic delay. Hence the interest of our study which consists in providing ENT specialists and all practitioners with the necessary clinical, evolutionary, radiological, biological and histological elements to avoid diagnostic errors. This is a retrospective study of all patients who were hospitalized for necrotizing otitis in the department of otolaryngology of the hospital of specialties of Rabat spread over a period of 5 years. All patients received an admission CT scan, biological tests, bacteriological sampling and biopsy. As well as initial parenteral antibiotic therapy and surgery for incidentally discovered EAC carcinomas. Clinically, all patients had otalgia and granulation tissue on otoscopic examination under the microscope. 50% had otorrhea. Pseudomonas aeruginosa was isolated in 50% of the cases, staphylococcus aureus in 25% and sterile culture in 25%. From the first biopsy, the diagnosis of tumor was retained in 6/10 patients. A second biopsy was performed in patients who did not show improvement and had a sterile culture. This one allowed the diagnosis in 4 other patients. All our patients had a surgical indication and were operated and then irradiated. The survival at 5 years was 50%. Biopsy must be systematic for every patient hospitalize for necrotizing otitis. Without hesitating to do it again each time the evolution is not good and the culture is sterile.

Imaging the External Ear: Practical Approach to Normal and Pathologic Conditions

The external ear (EE) is an osseous-cartilaginous structure that extends from the auricle to the tympanic membrane. It is divided into two parts: the auricle (or pinna) and the external auditory canal (EAC). Given the ease of access to the EE, imaging studies are not always needed to make a diagnosis. However, when lesions block visual access to areas deep to the EE abnormality, complications are suspected, or there is lack of response to treatment, imaging becomes essential. A basic understanding of the embryologic development and knowledge of the anatomy of the auricle and EAC are useful for accurate diagnosis of EE lesions. Congenital, traumatic, inflammatory, neoplastic, and vascular conditions can affect the EE. An overview of the anatomy and embryologic development of the EE is presented, with discussion and illustrations of common and uncommon conditions that affect EE structures and a focus on the CT and MRI features that are of interest to radiologists. CT is usually the first diagnostic modality used to evaluate the EAC and is the superior method for demonstrating bone changes. MRI provides excellent tissue characterization and enables one to better define lesion extension and perineural tumor spread. In addition, a flowchart to facilitate the differential diagnosis of EE abnormalities is provided. Online supplemental material is available for this article. ^©RSNA, 2022.

Squamous Cell Carcinoma of the External Auditory Canal and Temporal Bone: An Update

Squamous cell carcinoma (SCC) is the most common primary malignancy to affect the temporal bone, including primary cutaneous SCC of the pinna, external auditory canal, middle and inner ear. This anatomically complex region generates complicated three-dimensional specimens that can be a challenge for macroscopic and microscopic pathologic assessment. A universally accepted staging classification for these malignancies is still to be established. A brief summary of the regional anatomy, etiology and epidemiology, presentation and diagnosis, radiologic assessment and treatment follows with a review of the pathologic assessment of the different types of specimens generated and an update on staging for SCC of the temporal bone.

The contribution of CT and MRI in staging, treatment planning and prognosis prediction of malignant tumors of external auditory canal

Carcinomas of external auditory canal (EAC) are rare. Radiological imaging particular in computed tomography (CT) and magnetic resonance imaging (MRI) plays an important role in the staging, treatment planning and follow up of the patients with malignant EAC tumor. This article aims to review the role of CT and MRI in the describing different tumor growth pattern, tumor staging, treatment planning, follow up and predicting the prognosis of malignant tumors of EAC.

Radiological Findings of Malignant Tumors of External Auditory Canal: A Cross-Sectional Study Between Squamous Cell Carcinoma and Adenocarcinoma

The primary malignant tumors of external auditory canal (EAC) are rare. The purpose of this study is to compare the imaging features of growth and recurrence pattern between 2 most common carcinomas namely squamous cell carcinoma (SCC) and adenocarcinoma of the EAC.This is a retrospective study involving 41 patients with primary EAC carcinomas of which 22 are SCC and 19 are adenocarcinoma. They were all scanned with high resolution computer tomography (HRCT) and magnetic resonance imaging. Follow-up clinical and imaging studies have also been collected and compared with a median follow-up time of 43 months (range 5-192 months). Necrosis was presented as hypodensity on computed tomography images, hyper-intense on T2WI and heterogeneous enhancement.Eighteen patients were diagnosed to be in T1 and T2 stage, it was found that SCC involved both the cartilaginous part and the bony part of the EAC (11/12), whereas adenocarcinoma involved only the cartilaginous part (6/6) (P < 0.01). Twenty-three patients were diagnosed to be in T3 and T4 stage showed bony involvement and adjacent tissue involvement for both SCC and adenocarcinoma. Parapharyngeal space involvement is much more common in recurrent SCC (P = 0.02). Lymph node metastasis was seen in 6 out of 22 patients with SCC, while 5 out of 19 patients of adenocarcinoma had lung metastasis, even at early stage (1/6; 1/5). Necrosis is more likely to occur in the patients with SCC (9/10) than that of adenocarcinoma (3/13) (P = 0.02).SCC and adenocarcinoma is seen to have different growth pattern at early stage but share similar patterns in the advanced stage. Lymph node metastasis is commonly seen in patients with SCC while adenocarcinoma shows lung metastasis even at early stage.

CT and MRI findings of radiation-induced external auditory canal carcinoma in patients with nasopharyngeal carcinoma after radiotherapy

OBJECTIVE

To summarize the radiological and clinical features of radiation-induced external auditory canal carcinomas (RIEACCs) in patients with nasopharyngeal carcinomas (NPCs) after radiation therapy.

METHODS

CT, MRI and clinical features in 16 patients with histologically proven RIEACCs were retrospectively reviewed. There were 2 females and 14 males, with a median age of 52.5 years at the time of diagnosis of RIEACC. Imaging parameters including lesion extent, size, margin, shape, bone destruction, adjacent structure invasion, density/signal intensity, and pattern and degree of enhancement were assessed. Clinical features including clinical staging, histological type, treatment and radiation dose (RD) of primary NPC as well as the histological type, staging of radiation-induced tumour and the latent period between NPC and RIT were recorded.

RESULTS

All patients had a single RIEACC. The lesions had a size of 3.5 ± 1.4 cm and were localized (n = 7) or extensive (n = 9). Most of the lesions were partially or ill defined with an irregular shape and had an intermediate density/signal pattern and moderate homogeneous enhancement. The latent period of RIEACCs ranged from 10 to 20 years in nine patients with a RD of 68-70 Gy; from 2 to 10 years in five patients with a RD of 68-74 Gy; and more than 20 years in two patients with a RD of 70 or 72 Gy.

CONCLUSION

An external auditory canal (EAC) mass with homogeneous, intermediate CT density or signal intensity in patients with NPC after radiotherapy is highly suggestive of RIEACC, which should be included in the routine surveillance for patients with NPC after radiotherapy.

ADVANCES IN KNOWLEDGE

RIEACCs could occur as short as 2 years after radiotherapy in patients with NPC and have distinct features from otitis media and sarcomas. This EAC malignancy should be included in routine surveillance for patients with NPC after radiotherapy.

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE

Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.

MATERIALS AND METHODS

Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.

RESULTS

Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.

CONCLUSIONS

CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.