# External auditory canal chondroid syringoma with bone erosion: A CARE case report.

J. Connesson, Cyril Beck, Christophe Vincent, Philippine Toulemonde

► To cite this version:

J. Connesson, Cyril Beck, Christophe Vincent, Philippine Toulemonde. External auditory canal chondroid syringoma with bone erosion: A CARE case report. European Annals of Otorhinolaryngology, Head and Neck Diseases, 2024, European Annals of Otorhinolaryngology, Head and Neck Diseases, 142 (2), pp.93-96. 10.1016/j.anorl.2024.11.004. hal-05264735

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Case report

# External auditory canal chondroid syringoma with bone erosion: A CARE case report

<figure><img src="image_2.png" /></figure>

J. Connesson, C. Beck, C. Vincent, P. Toulemonde*

Département d'otoneurologie, université de Lille, CHU de Lille, 2, Henri-Warembourg, 59000 Lille, France

## INFO ARTICLE

**Keywords :**

Chondroid syringoma

Ceruminous pleomorphic adenoma

Mixed cutaneous tumor

Bone erosion

## ABSTRACT

**Introduction.** – Chondroid syringoma or ceruminous pleomorphic adenoma is a benign mixed cutaneous tumor. It is the second most frequent glandular lesion in the external auditory canal, but no cases associated with bone erosion were found in a PubMed search.

**Case report.** – The present CARE case report details a chondroid syringoma in the external auditory canal with associated bone lysis, and its management.

**Discussion.** – Chondroid syringoma is a differential diagnosis for other external auditory canal tumors. Forms causing bone erosion are rare, but should not challenge the diagnosis. Current treatment consists in complete and broad surgical resection and prolonged follow-up due to the risk of recurrence and of malignant transformation.

© 2024 The Author(s). Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

## 1. Introduction

Primary glandular lesions of the external auditory canal are rare, at just 5.7% of pinna and canal lesions [1]. Terminology and classification are disputed [2-4]. The latest WHO classification distinguishes benign ceruminous gland lesions as adenoma, pleomorphic adenoma and syringocystadenoma papilliferum [5].

Chondroid syringoma refers to pleomorphic adenoma developing from the cutaneous appendices [6-8]. It is a mixed cutaneous tumor diagnosed on pathology, characterized by subepithelial proliferation of glandular structures with networks of myo-epithelial components in a chondromyxoid stroma [8,9]. Location is most often head and neck. It is usually weakly symptomatic, with slow growth and no adjacent bone erosion [7,10,11]. Like with parotid pleomorphic adenoma, malignant transformation is possible [7,12].

The aim of the present study was to report a case of chondroid syringoma of the external auditory canal, causing bone lysis, and to describe management, following the CARE guidelines [13].

## 2. Case report

A 48-year-old woman with history of intellectual deficiency secondary to postnatal encephalopathy consulted for a lytic lesion of the right external auditory canal, known for 3 years. She

expressed no complaints, such as otalgia or otorrhea, and had had no diagnostic or therapeutic treatment. She was referred due to tumor growth with externalization of the lesion through the external auditory canal. Cervico-parotid and oral cavity palpation was normal. Head and neck and temporal bone CT with and without contrast enhancement showed a poorly contoured 34 mm tissular lesion palpation entirely filling the right external auditory canal, with contact lysis and contrast uptake (Fig. 1). The mass invaded the ear-drum and extended anteriorly in contact with the posterior edge of the parotid. MRI could not be performed due to lack of cooperation. Definitive pathology examination of biopsies found an extensive pleomorphic adenoma or chondroid syringoma of the external auditory canal, without histologic criteria of malignancy. Broad resection was performed, with right lateral temporal bone resection and ipsilateral exofacial parotidectomy. There was no macroscopic parotid involvement.

Pathologic and immunohistochemical analysis of the specimen found invasion of the external auditory canal, and posterior bony wall and ear-drum by a chondroid syringoma without criteria of malignancy (Fig. 2) or parotid involvement. There were no postoperative complications, and no complementary treatment was given. Ten months' clinical monitoring found no complications or signs of recurrence. The first annual head and neck and temporal bone contrast-enhanced CT check was scheduled for 1 year post-surgery.

<footnote>* Corresponding author.
Adresse e-mail: philippine.toulemonde@chu-lille.fr (P. Toulemonde).</footnote>
<figure><img src="image_3.png" /><figcaption>**Fig. 1.** CT scan of the temporal bones without contrast injection, in axial plane (on the left) and a cranial CT scan with contrast (on the right). Lytic tissue lesion of the right external auditory canal causing adjacent bone erosion (green arrows), extending into the middle ear, and coming into contact with the posterior pole of the parotid gland.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>**Fig. 2.** Photomicrograph of a histological section of chondroid syringoma shows tubules, ducts and cysts embedded in a chondromyxoid stroma (H&E, 20×).</figcaption></figure>

### 3. Discussion

Pleomorphic adenoma is the most frequent tumor of the salivary glands. The main location is the parotid gland, in 85% of cases [14]. Pleomorphic adenoma of the external auditory canal is rare, but can develop from an ectopic salivary gland or extension of a parotid pleomorphic adenoma via the foramen of Huschke (foramen tympanicum) [15,16]. When the origin is in cutaneous annexes such as the ceruminous glands, it is referred to as chondroid syringoma or ceruminous pleomorphic adenoma [6,17–19]. Chondroid syringoma is mainly located in the head and neck region. When located in the external auditory canal, differential diagnoses comprise malignant epithelial tumor, extension of parotid pleomorphic adenoma or basal cell carcinoma.

Chondroid syringoma usually presents as a poorly symptomatic painless tumor with slow growth and no adjacent bone erosion [10,11,20]. Malignant transformation is rare, but possible in case of long-term progression [21–25]. Without malignancy, some may show rapid progression or bone erosion; a PubMed search retrieved 1 case of rapid growth chondroid syringoma in the external

auditory canal and 4 cases with bone erosion in the upper lip and lacrimal glands [7,26–29].

MRI shows a well-contoured lesion, hypointense on T1 and hyperintense on T2 weighted sequences in comparison to the parotid gland, with gadolinium uptake. The MRI aspect is non-specific, but extension, origin and depth can be assessed [30,31]. In the present case, the patient's poor cooperation made MRI impossible, and extension was assessed on contrast-enhanced CT.

Like for salivary gland pleomorphic adenoma, relapse can occur in the external auditory canal in case of incomplete resection or intraoperative tumor rupture. Complete wide resection is thus essential to prevent recurrence [14,31,32].

In the present case, wide resection was performed, with lateral temporal bone resection and exofacial parotidectomy, as there were no intraoperative signs of macroscopic invasion of the parotid gland. Within the ear-drum, resection appeared macroscopically complete, but was not monobloc; margins in the inner ear were thus narrow and pathologic analysis was not possible.

In the literature, radiotherapy was assessed only as adjuvant treatment after wide resection of malignant chondroid syringoma
[33,34]. However, fewer than 50 cases of malignant chondroid syringoma could be retrieved from the PubMed database, with very variable adjuvant treatments [21].

By analogy, postoperative radiotherapy in parotid gland pleomorphic adenoma after resection with narrow or positive margins ensured excellent locoregional control and low treatment-related morbidity [35].

In the present case, lack of patient cooperation precluded adjuvant radiotherapy.

Diagnosis is pathologic, often associating immunohistochemistry [9,20,36,37]. In the present case, the absence of parotid involvement and the pathology results indicated a diagnosis of mixed tumor of cutaneous rather than salivary origin, confirming the hypothesis of primary external auditory canal chondroid syringoma developing from the cutaneous sebaceous glands [6,17,18]. Osteolysis has not often been reported to be associated with chondroid syringoma, and delayed treatment may be implicated in the present case. That no bone lysis was reported in the literature may be due to chondroid syringoma being frequently facial and thus visible, with slow growth.

Follow-up must be prolonged due to the risk of recurrence and of malignant transformation [14,32]. Monitoring modalities depend on lesion location and definitive pathology results; there is no consensus on the rhythm of monitoring. By analogy with salivary gland pleomorphic adenoma, MRI is the examination of choice [30].

In the present case, monitoring was clinical, every 3 months. Annual head and neck and temporal bone CT was planned.

## 4. Conclusion

Chondroid syringoma is a differential diagnosis for other external auditory canal tumors. Forms causing bone erosion are rare, but should not challenge diagnosis. Treatment consists in complete and wide surgical resection and prolonged follow-up due to risk of recurrence and malignant transformation.

## Consent

The patient's guardian provided informed consent for publication of medical data. The patient's own consent was sought.

## Disclosure of interest

The authors declare that they have no competing interest.

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