Isolated Myxoma of the External Auditory Canal: A Rare Case Report

Eun Kyung Jeon; Min Heon Kim; Dong Hwan Kwon; Young Joon Seo

doi:10.7874/jao.2024.00423

Abstract

Isolated myxomas of the external auditory canal are extremely rare, benign tumors. We present a case of a 77-year-old male patient who presented with a benign mass in the right external auditory canal. Isolated myxomas of the tragus around the external auditory canal are rare. This case report highlights the clinical presentation, surgical management, and pathological findings of this patient. The importance of considering myxoma in the differential diagnosis of benign tumors of the external auditory canal is emphasized. Long-term follow-up is necessary to monitor for potential recurrence or associated conditions. Further studies are needed to better understand the etiology, pathogenesis, and optimal management of this rare type of tumor.

Keywords: Myxoma · Ear canal · Carney complex.

Introduction

Tumors of the external auditory canal are one of the various tumors that can occur in tissues around the ear. Among these, myxomas found in the external auditory canal are reported to be extremely rare [1]. Myxomas are benign tumors that arise from mucous cells originating in skeletal muscle, soft tissue, and vascular endothelium, and are characteristically rich in mucoid or mucinous components compared to the surrounding tissues [2,3]. Due to this, the tumor has a mucous-like appearance, and is characterized by being soft and slowly growing. These tumors are associated with genetic mutations in congenital connective tissues and may often be related to a rare genetic condition known as Carney complex [4]. Carney complex is a syndrome that accompanies various symptoms, including skin pigmentation, endocrine disorders, and endocrine and non-endocrine tumors.

In 1871, Virchow first used the term “myxoma” for a tumor with histological characteristics similar to the mucous tissue of the umbilical cord [2]. Later, in 1948, Stout established the generally accepted diagnostic criteria for myxomas, reporting that they are true tumors composed of stellate cells, situated in a loose mucinous tissue intersected by fine reticulin fibers running in different directions [3].

Since cartilage is a tissue composed of mucous cells, myxomas can also occur in cartilage tissue [5,6]. Cartilage myxomas occur relatively rarely within the cartilage tissue, but cases have been reported in various parts of the body. The most common sites of occurrence are joint areas, especially in the head of the femur, plantar muscles, wrists, and back joints [7,8]. In Korea, 10 cases of myxomas have been reported in the head and neck area, including the maxilla, larynx, and neck [4,6,8,9]. However, detailed research reports on myxomas found in the external auditory canal have not yet been reported. Myxomas in the external auditory canal, due to their specificity, can be clinically difficult to diagnose, and a fundamental understanding and appropriate treatment planning are important.

Therefore, the purpose of this study is to report the clinical characteristics, diagnostic approach, and treatment outcomes of isolated myxomas found in the auricle of the external auditory canal. Through this, we hope to lay the foundation for future research and treatment strategies for myxomas of the external auditory canal, and to help provide optimal treatment for patients.

Case Report

A 77-year-old male patient with no specific past medical history presented to the otolaryngology outpatient clinic with a mass palpable in front of the tragus of the right external auditory canal. The mass had been growing slowly without pain over several months, and the patient did not complain of hearing loss or other symptoms. A diffuse, firm benign mass approximately 5 mm in size was palpable in front of the tragus, and no fistula was found nearby. Computed tomography of the temporal bone revealed a circular mass about 1.5 cm in diameter in front of the right external auditory canal tragus (Fig. 1). Under local anesthesia, a surgical resection of the benign mass was performed through a trans-tragal incision. The mass, which was 5 mm in size and spherical in shape, was completely removed with relatively well-secured margins (Fig. 2). The mass was attached to the tragus without forming a boundary with the perichondrium of the tragus, and the tragus cartilage itself was not resected; only the mass was removed. Pathological examination post-surgery confirmed the mass as a myxoma. Immunofluorescence staining post-surgery showed positive staining for S-100, actin, calretinin, and CD34 (Fig. 3). The patient was followed up for more than 3 months without additional treatment, and no recurrence or scarring was observed at the surgical incision site (Fig. 4).

Discussion

Benign masses of the external auditory canal are diverse and can exhibit various forms and histological features [2,3]. The causes of tumor development are varied, and the exact cause is still not clearly understood. However, congenital factors, inflammation, external stimuli, and genetic mutations may be related to the development of tumors [4]. Fibromas, tumors originating from fibrous tissue, typically have a fixed size and shape and appear as soft, elastic lumps. Lipomas, originating from fatty tissue, appear as soft, movable masses, often formed by clusters of fat cells, and can occur under the skin or behind the ear [7]. Epidermoid cysts form when the passage of sebaceous glands in the skin gets blocked, forming a lump with sebum, appearing as a round shape under the skin, and often showing a black spot (sebum grape) on the skin surface [10]. Seborrheic keratosis, originating from skin keratinocytes, usually appears brown or black with a rough surface and can resemble myxoma [11]. Neurofibromas, tumors originating from nerve tissue, can rarely occur in the external auditory canal, appearing as soft lumps under the skin, often showing small speckled Lisch nodules on the skin surface [12]. Accurate identification of tumors around the external auditory canal requires a biopsy, and the appropriate treatment method should be determined based on the characteristics and symptoms of the tumor.

Myxomas can be diagnosed through pathological findings, where the cells are round or polygonal and surrounded by brown or transparent mucinous material [1,2]. The cells are composed of thin fibroblasts arranged in a loose mucinous matrix, with these fibroblasts aligned with reticulin fibers formed in various directions. The cell nuclei are generally round and of normal shape, and in fluorescent staining, they can show a positive reaction to certain antibodies. In this case, additional immunofluorescence staining showed positive staining for S-100, actin, and calretinin, while CD34 was not stained [2,4,12]. This shows the characteristic immunofluorescence staining pattern of a myxoma. S-100 is a protein associated with nerve tissue, indicating the tumor’s neural origin. Actin, a protein expressed in muscle tissue, can indicate the tumor’s muscular origin. Calretinin is a calcium-binding protein, indicating the tumor’s neural or vascular origin. CD34, known as a marker for vascular endothelial cells, was not stained in this case, suggesting a lack or small amount of vascular component in the tumor [6]. Differential diagnosis can distinguish it from similar benign tumors, such as neurofibromas, which are composed of nerve fibers and may show different antibody staining results in the nucleus. Fibromas, benign tumors originating from fibrous tissue, may histologically resemble myxomas, but they must show the characteristic shape of fibrous tissue along with other components. Also, schwannomas are typically positive for S-100 staining but negative for actin, calretinin, and CD34 in most cases. On the other hand, chondromas are generally positive for calretinin staining but negative for S-100, actin, and similar markers. These staining characteristics can aid in differentiating myxomas from other tumors.

Myxomas are mostly benign, and malignant transformation occurs very rarely [12]. However, cardiac myxomas can obstruct blood flow in the heart or cause symptoms such as dilation, constriction, or occlusion of the heart, so early detection and treatment are important, with surgical resection being the main treatment method. Incomplete resection of the primary tumor, multiple lesions, and familial tendency can contribute to the recurrence and malignant potential of cardiac myxomas. Malignant transformation of myxomas is an exceptional situation, and, due to insufficient evidence, treatment should be decided based on the size and location of the tumor and the patient’s individual factors [13]. Carney complex is an autosomal dominant syndrome characterized by myxomas in the heart and skin, skin hyperpigmentation, and endocrine hyperactivity [2]. It is diagnosed based on clinical criteria, and genetic testing may be necessary to test for the most common mutation associated with the syndrome, PRKAR1A. In the context of Carney complex, myxomas can be found in the cartilaginous wall of the external auditory canal. Therefore, when diagnosing a myxoma of the ear, it is important to consider the possibility of Carney complex and to perform additional tests to rule out accompanying conditions such as skin hyperpigmentation, endocrine tumors, or neurofibromas.

This case reports on a myxoma that slowly grew attached to the tragus near the external auditory canal and covers a rare case of a benign mass occurring in the external auditory canal. Myxomas typically occur in the heart and other soft tissues, with occurrences in the external auditory canal being extremely rare. This paper details the clinical features, diagnosis, surgical treatment, and course of a myxoma found in the external auditory canal, and reports on the characteristic histological findings and immunofluorescence staining results of myxoma. Additionally, this case discusses the complications, recurrence potential, and association with Carney complex of myxomas of the external auditory canal, emphasizing the importance of clinical management and diagnosis of rare diseases.

Notes

Ethics Statement

This study was approved by the Institutional Review Board (IRB) of Yonsei University Wonju Severance Christian Hospital (CR323350) for human subject research.

Conflicts of Interest

The authors have no financial conflicts of interest.

Author Contributions

Conceptualization: Eun Kyung Jeon. Data curation: Min Heon Kim. Formal analysis: Dong Hwan Kwon. Funding acquisition: Eun Kyung Jeon. Investigation: Min Heon Kim. Methodology: Dong Hwan Kwon. Project administration: Dong Hwan Kwon. Resources: Min Heon Kim. Software: Eun Kyung Jeon. Supervision: Eun Kyung Jeon. Validation: Min Heon Kim. Visualization: Dong Hwan Kwon. Writing—original draft: Eun Kyung Jeon. Writing—review & editing: Min Heon Kim, Dong Hwan Kwon. Approval of final manuscript: all authors.

Funding Statement

The present study was grant-funded by three institutions supported by the Commercialization Promotion Agency for R&D Outcomes (RS-2025-02310434).

Acknowledgments

None

Fig. 1.

Computed tomography of temporal bone. A round-shaped soft tissue density mass (arrowhead) on the right preauricular area was noted.

Fig. 2.

A surgical resection of the benign mass was performed through a trans-tragal incision. A and B: Intraoperative findings. C: About 1.5 cm diameter mass.

Fig. 3.

Histological findings (×100). A: S-100. B: Actin. C: Calretinin. D: CD34.

Fig. 4.

Operation site shows well-healed status after 3 months of treatment.

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