Eustachian Tube Teratoma: A Rare Entity

Introduction

Teratomas are tumors derived from all of the 3 fetal germ cell layers and different from the tissues of the part of the body in which they arise. ¹ The term was introduced by Virchow but finally classified by Albert ² and comes from the Greek “terat” which means “monster.”

According to the definition, teratomas may contain different combinations of elements from the ectoderm (skin and its appendages, neural tissue), mesoderm (muscle, bone, adipose and fibrous tissue, cartilage) and endoderm (thyroid gland, respiratory ciliated tissue, salivary tissue).

Teratomas are classified as monodermal, immature, mature and mixed types. ³ . The monodermal tumors are made of derivates of a single germ layer (generally ectoderm). The immature teratomas are generally malignant and their prognosis is related to their histological grading (0 -3). ⁴ The mature teratomas are classified into solid, cystic, with malignant transformation and foetiform.

The head and neck teratomas represent 10% of all germ cell tumors ⁵ but the Eustachian tube is an uncommon site for this kind of tumor. In children head and neck teratomas are usually diagnosed early due to frequent symptoms such as respiratory distress (even if benign tumors, they can become locally aggressive), facial disfigurement and orbital involvement. ³

Protocols for investigation of teratomas in children (especially immature/malignant) recommend imaging (CT scan and MRI) and preoperative and postoperative assessment of characteristic tumor markers (alpha-fetoprotein and beta-hCG), as they can be secreting tumors. These markers play an important role in the initial diagnostic evaluation of a teratoma as well as in the follow-up examination of the patient after surgical removal of the tumor. Raised levels of alpha fetoprotein (AFP) and beta-human chorionic gonadotropin (hCG) raise suspicion of teratomas preoperatively, without histological confirmation, and are also useful for postoperative monitoring of immature teratomas, raising suspicion of tumor recurrence. ⁶

The authors present a case of an Eustachian tube teratoma in a 2 years old child. Written informed consent from the child’s parents and approval from the Hospital’s Ethics Committee (approval no. 45595/21.10.2022) were obtained to publish this report in accordance with the journal’s patient consent policy.

Case Report

A 2 years old girl was admitted to our ENT department with foul smell aural discharge from her right ear, dating back for the last 2 months. The history revealed a child that was born at 36 weeks of gestation, by cesarean section, birth weight 2700 g.

She was diagnosed with right serous otitis media at 3 months old. At 6 months she had a tympanotomy with insertion of an aeratory Shepard tympanostomy tube in her right ear.

A CT scan performed at 7 months old showed a cystic tumor located in the area of the protympanum and right eustachian tube, with dimensions of 15/20 mm and lack of ventilation of the right middle ear cleft (Figure 1).

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Figure 1.

CT scan at 7 months old: cystic appearance of the right eustachian tube; lack of middle ear aeration on the right side.

An adjunct nasopharyngeal endoscopy did not show any tumor at the level of the rinopharynx. Because the parents were reluctant to any surgery, the child was monitored on a regular basis. At the age of 1, the tympanostomy tube was removed, allowing for the tympanic membrane to heal. Subsequent MRI showed the same cystic-like appearance of her right eustachian tube, with a non homogenous content and complete lack of middle ear ventilation (Figure 2).

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Figure 2.

MRI at 1 year old: Right eustachian tube occupied by a cystic tumor.

She had multiple episodes of acute otitis media in her right ear between the age of 12 and 21 months, generally improving after variate antibiotic regimens.

At 22 months-old, in spite of specialist referral and different medications used, the patient presented with a foul aural discharge in her right ear that did not respond to any topical or general antibiotics.

Upon presentation to our department, examination of her ear revealed a superior (Schrapnell membrane) perforation, with small granulation tissue on the surface of the tympanic membrane. In agreement with the parents, we opted for surgical exploration using the operating microscope under general anesthesia. Whitish discharge through the perforation could be elicited during microscopic examination. A whitish mass was visible into the antero-inferior quadrant of the tympanic membrane. Due to the suspicion of middle ear cholesteatoma, middle ear exploration was planned. After discussion with the child’s parents, we proceeded further to surgery during the same session.

Posterior-superior (transmastoid) approach was used. Cholesteatoma was found in the aditus ad antrum and in the upper part of the middle ear space. After performing posterior tympanotomy for better view, we discovered a white mass bulging into the protympanum and going slightly down toward the inferior part of cavum tympani (middle ear space). Traction and dissection of the mass did not reveal any more cholesteatoma lesions but we performed a canal wall down mastoidectomy procedure in order to fully expose the tumor. Its peripheral dissection and traction allowed eliciting of a hairy, ferm, whitish tumor that could be excised with some difficulty, apparently in a single piece, due to its profound attachments inside the medial part of the Eustachian tube (Figure 3). Nasopharyneal endoscopy showed a normal sized residual right eustachian tube orifice (Figure 4). Tympanic membrane reconstruction with temporalis fascia and conchal cartilage were undertaken, keeping the mastoid cavity largely open through an enlarged external meatus.

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Figure 3.

Intraoperative views, showing progressive removal of the tumor of a tumor. We can identify: the malleus (M), stapes head (S), and tumor (T). Later in removal process, hair follicles (H) are clearly visible on the surface of the tumor.

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Figure 4.

Intraoperative nasopharyngeal endoscopy at the end of the surgical tumor removal.

The excised tumor was send to Pathology Department for microscopic examination. Grossly, the tumor had a firm consistency with a whitish, fine hairy surface. Preparing the sample began with fixation. The tumor was immersed in a 10% formaldehyde solution for 24 hours, until the next day. Then the tissue was processed in an automatic tissue processor Leica ASP200, it was included in histological parrafine and the blocks were sectionated to 5 µm thick. The slides made from formalin fixed paraffin embedded-tissue were routinely stained with Hematoxylin-Eosin (HE) and with special stain Van Gieson.

The microscopic examination revealed a tumor composed of mature tissues derived from the 3 fetal germ cell layers: bone, fibro-adipose tissue, blood vessels, sero-mucous glandular acini, ductal structures layered by ciliated columnar respiratory epithelium (Figure 5b); the tumor was covered by squamous epithelium with skin appendages and hair (Figures 5a and c).

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Figure 5.

Histologic sections of the Eustachian tumor appearance: (a) Fibroadipose tissue covered by squamous epithelium with skin appendages, H&E stain, 100X, (b) A mixture of bone trabeculae, fibrous tissue, sero-mucous glandular acini, ductal structure layered by ciliated columnar respiratory epithelium, H&E stain, 100X, and (c) The tumor surface was covered by skin with skin appendages and hair shafts, Van Gieson stain, 100X.

The diagnosis of Eustachian tube mature teratoma was established.12 months after the excision, the patient presented a residual mastoid cavity, with complete atelectasis of the remaining eardrum over the medial middle ear wall. A deep protympanum was obvious. Keratin debridement and removal was performed as needed.

Discussion

Congenital teratomas have an incidence of 1 on 20 000 to 40 000 births. ⁷

Eustachian tube teratoma is an unusual location for this kind of malformation. Until 2013, only 16 cases had been reported in the literature, originating here.^{2,8 -10} It is a tumor-like malformation containing cells from all the 3 germ layers (endoderm, mesoderm, ectoderm). Different names had been assigned to these teratomas, according to the various proportions and nature of its cells: mature teratoma, malignant teratoma, epignathus. Sometimes, they are difficult to differentiate from other tumors originating in less than 3 germ cell layers: hairy polyps of the nasopharynx or congenital dermoid cysts and hamartomas.^{11 -13} Only 13 cases of dermoids originating in the eustachian tube have been published. ¹³

It is also notable that not all published teratomas were located strictly inside the Eustachian tube but bulged into the nasopharynx through a long pedicle.^8,10,14 Our case showed no extension of the tumor toward the airways, explaining the absence of respiratory symptoms in our child.

The evolution and diagnosis of these teratomas depend on their development: toward the rhinopharynx, leading to respiratory problems or toward the middle ear, leading to hearing deficits and chronic ear disease. In some children with chronic ear effusion, when refractory to therapy and diagnosis is unclear, a differential diagnosis of a middle ear tumor (teratoma) should be taken into account. Imaging (CT/MRI) or even surgical exploration are decisive when in doubt.

In our case, combined lack of a proper specialist diagnose and reluctancy of child’s parents to surgery resulted in chronic ear disease, mainly a middle ear cholesteatoma. We did not have any reasons to consider other sites of origin for this teratoma but the eustachian tube due to the fact that no mass was obvious in the rhinopharynx during endoscopy.

Surgery with complete removal is the main therapeutic approach for congenital teratomas. ⁷ Recurrences are possible.^7,15

The extraction of the teratoma by means of a canal wall down mastoidectomy seemed pretty hard to decide, but we could not have succeeded with a very narrow approach, offered by posterior tympanotomy. Canal wall down mastoidectomy allowed us a clear dissection and avoided trauma to the surrounding structures. Although the teratoma seemed difficult to remove (having an adherent pedicle) it was fully removed. No recurrence of the tumor was observed 1 year later.

Some therapeutic issues can arise in the presence of a teratoma located in the protympanum and Eustachian tube. The decision to perform an open mastoid cavity was taken for a better approach to the cholesteatoma. Full scar obliteration of the eustachian tube can be long-term challenging. Chronic atelectasis of the middle ear cleft can occur. Chronic ventilation of the middle ear with tympanostomy tubes can also be an option in certain cases. Due to the funnel-shape of the tympanic Eustachian orifice the epidermal debris of a mastoid and tympanic cavity can become lodged on site and prevent healing of the residual cavity/ear canal. Subtotal petrosectomy could also represent a possible management approach in such cases but we did not perform it, due to lack of proper knowledge on the hystologic nature of the resected tumor. Also, such extensive surgery should be limited by worse functional results in terms of hearing. In our case, hearing levels remained unaffected by surgery.

Teratoma composed of mature cellular elements show a higher degree of differentiation, are classified as benign and do not produce tumor markers. Mature or immature teratomas in childhood are usually detected preoperatively by imaging methods (CT scan or MRI) while investigating nonspecific clinical findings (such as precocious puberty in children)^16,17 due to increased levels of alpha 1 fetoprotein or beta hCG. No suspicion of teratoma was raised in our case preoperatively due to unspecific and unusual symptoms (chronic ear discharge, no respiratory symptoms) and unspecific imagery; surgery was performed expecting a middle ear cholesteatoma; the diagnosis of mature Eustachian tube teratoma came as a complete surprise after surgical removal of the tumor and histopathological examination. That is why in our case no preoperative levels of ASFP or beta-hCG were obtained; levels of AFP 1 and beta-hCG measured postoperatively at 3 weeks and at 1 year were in normal range for child’s age.

Conclusions

Eustachian tube teratoma is a rare occurring tumor. Clinical presentation can mimic and cause the appearance of a middle ear cholesteatoma. It can be recognized by its cystic appearance on MRI/CT imaging. Management includes surgical removal and detailed evaluation of the residual eustachian tube lumina. In our case, we could remove the teratoma through canal wall down mastoidectomy, together with a secondary acquired middle ear cholesteatoma. Immediate blockage of the eustachian tube function was obvious during the first year after surgery, possibly by local scarring. In cases with large anatomic communication of the middle ear spaces with the rhinopharynx, we appreciate that subtotal petrosectomy and eventually bone anchored hearing device (BAHA) could represent the best options available.