Key points

Introduction

Malignancy of the ear and temporal bone in the pediatric population is a complex and challenging problem for many reasons. Cancer in children evokes a particular energy that supercharges emotions; thus, attending to these patients requires an extra measure of empathy, professionalism, and objectivity. In addition, malignant tumors of the ear and temporal bone are extraordinarily uncommon in children, rendering clinical decision making difficult. It is often necessary to infer best practice from outcomes reported for the management of these tumors treated in other parts of the body or for similar tumors occurring in adults. Reliance on the expertise of other oncologic specialists and the need for periodic review of the pertinent medical literature is expected when an obscure tumor is at hand because it would be rare in the career of a skull base surgeon to ever develop a working familiarity and comfort with all the various forms of cancer that can potentially involve the ear and temporal bone of a child. Therefore, this article provides an overview of some of the malignant tumors of the ear and temporal bone that occur in children with a particular emphasis on RMS. In addition, it outlines the key principles of evaluation and management that have particular relevance to the pediatric perspective.

Introduction

Malignancy of the ear and temporal bone in the pediatric population is a complex and challenging problem for many reasons. Cancer in children evokes a particular energy that supercharges emotions; thus, attending to these patients requires an extra measure of empathy, professionalism, and objectivity. In addition, malignant tumors of the ear and temporal bone are extraordinarily uncommon in children, rendering clinical decision making difficult. It is often necessary to infer best practice from outcomes reported for the management of these tumors treated in other parts of the body or for similar tumors occurring in adults. Reliance on the expertise of other oncologic specialists and the need for periodic review of the pertinent medical literature is expected when an obscure tumor is at hand because it would be rare in the career of a skull base surgeon to ever develop a working familiarity and comfort with all the various forms of cancer that can potentially involve the ear and temporal bone of a child. Therefore, this article provides an overview of some of the malignant tumors of the ear and temporal bone that occur in children with a particular emphasis on RMS. In addition, it outlines the key principles of evaluation and management that have particular relevance to the pediatric perspective.

Presentation

With a few caveats, the presentation of ear and temporal bone malignancy in children is similar to what is encountered in adults. Classically, these tumors mimic a severe and refractory ear infection. The most common presenting symptoms and signs are hearing loss, otorrhea, otalgia, headache, aural polyp, facial nerve weakness, and regional lymphadenopathy. However, unlike adult patients, children may be less apt to verbalize the presence of hearing loss and will typically have been treated for infection for a much longer period of time before the possibility of malignancy is considered. Also, it is important to recognize that children with cancer generally begin to lose weight and fail to thrive at an earlier stage than adults, especially very young children.

Assessment of neurologic function in affected children may reveal various cranial nerve deficits. Ophthalmic abnormalities such as visual loss, diplopia, proptosis, and chemosis are ominous indicators of a combined lateral and anterior skull base tumor with potential involvement of the cavernous sinus and orbital apex. Yet, diplopia due to isolated weakness of the sixth cranial nerve can be encountered in less-extensive temporal bone tumors that involve the petrous apex while still being confined to the base of the middle cranial fossa. Similarly, isolated numbness in the distribution of the mandibular branch of the fifth cranial nerve may be an indicator that tumor involves the lateral skull base in the infratemporal fossa without an extensive anterior skull base component. Indicators of lower cranial nerve dysfunction such as glottic insufficiency, dysphagia, shoulder weakness, or tongue weakness on the affected side suggest tumor invasion of the jugular foramen or hypoglossal canal. However, for a slow-growing tumor, symptoms of lower cranial neuropathy may be subtle because a child’s capacity to rapidly adapt and compensate can be surprisingly robust.

Depending on the extent and location of a malignant tumor in the temporal bone, other presenting signs and symptoms are possible. Trismus or pain with chewing may indicate tumor involvement of the temporomandibular joint or supporting muscles of mastication. Vertigo or imbalance may signify invasion of the labyrinth or vestibular nerve. In cases in which the ear and temporal bone are invaded secondarily, primary tumor of the parotid gland, pharynx, mandible, or upper cervical structures may be evident. Invasion of the dura or brain should be considered when cerebrospinal fluid leakage or a recent history of meningitis is present. Finally, obstruction of the sigmoid sinus or jugular bulb because of tumor bulk or direct invasion may infrequently cause symptoms of central venous congestion ranging from headache to cerebral edema.

Evaluation and diagnosis

Keeping the above-described signs and symptoms in mind, a detailed history is taken, and a complete head and neck examination that includes microotoscopy is performed. Audiologic testing is also undertaken to document hearing thresholds. When skull base disease process is suspected, the next diagnostic step is radiologic imaging. As this may be difficult to obtain in children, general anesthesia is a common requirement, and it is therefore ideal to complete all required testing at once, which in the case of a skull base tumor usually means acquisition of contrasted magnetic resonance imaging (MRI) and computed tomography (CT) in the same setting. Sometimes it is also possible to complete a soft tissue biopsy while the child is under anesthesia when tumor is evident on examination in an easily accessible location.

Evaluation of skull base disease relies heavily on radiologic imaging, and both MRI and CT are complementary in portraying a tumor’s characteristics and extent. Typical imaging characteristics of various malignant skull base lesions are portrayed in Table 1 .

One aspect unique in the assessment of pediatric ear and temporal bone malignancy that deserves mention is the need to differentiate cancer from Langerhans cell histiocytosis (LCH), a pseudomalignant process often encountered in children that may share several presenting features with malignant tumors such as chronic otorrhea, otalgia, headache, lymphadenopathy, and hearing loss. LCH (previously known as histiocytosis X) is a rare locally destructive condition that involves clonal proliferation of Langerhans cells, which in turn may migrate from skin to regional lymph nodes. LCH is considered a pseudomalignancy because many cases of spontaneous remission have been reported and also because much of the associated pathophysiology seems to be related to local cytokine-mediated reactive processes. Langerhans cells, which resemble epidermal dendritic cells, group together with lymphocytes and eosinophils to generate destructive inflammatory lesions, which can occur anywhere in the body. Diagnosis of LCH is strongly supported by the typical histopathologic appearance and positive immunohistologic staining for CD1a antigen, S-100, adenosine triphosphatase, and mannosidase. Definitive diagnosis is confirmed by the presence of Birbeck granules in the cytoplasm of affected Langerhans cells, which are evident on electron microscopy.

Treatment

Microsurgery

The decision to perform microsurgical resection of a malignant tumor from the ear and temporal bone of a child is made thoughtfully and is based on input from a variety of pediatric specialties including medical oncology, radiation oncology, otolaryngology, anesthesiology, neurosurgery, and facial plastic surgery. Choice of a particular surgical approach should be individualized based on a child’s tumor specifics (subtype, involved structures, stage) and tolerance of relevant surgical morbidity. It is critical that the patient, family, and treatment team are collectively in agreement with the goals and intended degree of aggressiveness of surgery, which may range from wide resection with curative intent to diagnostic soft tissue biopsy. If the projected morbidity of a planned surgical resection involves significant disfigurement, it is critically important to initiate early child and adult psychiatric consultations for support of the patient, siblings, and other family members. In addition, utilization of a child life specialist during periods of inpatient hospitalization may help the patient cope with fear and discomfort.

Although lateral skull base surgery in adults and in children is based on similar anatomic principles, there are a few particular considerations in children worth noting. First, because of future projected growth of a child’s craniofacial skeleton, it may be desirable to favor craniofacial plates that resorb if any are deemed necessary. Metallic plates not only have the potential to distort future radiologic imaging but also tend to progressively migrate into the inner table of the skull over time. Second, a young child’s tolerance of heavy blood loss is considerably less than that of an adult. This fact is particularly relevant if the surgeon intends to pursue tumor into the jugular foramen, where robust bleeding is commonplace. Thus, the decision to dissect tumor away from any of the great vessels should always be made cautiously and with appropriate preoperative preparation such as vascular imaging, blood products on immediate standby, interventional radiology availability, and proactive availability of relevant surgical materials (eg, Fogarty catheters, thrombin-soaked absorbable packing, vessel loops). Last, it should be kept in mind that a child’s tolerance of complex postoperative wound care is typically much less than what would be expected for an adult. Thus, reconstructive techniques that allow complete closure of the surgical wound and primary closure of the donor site, such as the anterolateral thigh free flap, are favored over techniques that might require repetitive ear cleaning or dressing changes such as a split thickness skin graft.

Although a comprehensive review of all microsurgical skull base approaches that can be used to approach a child’s temporal bone malignancy is not intended, a general subdivision and discussion of the most commonly used techniques for malignant temporal bone tumors is summarized in the discussion that follows.

Temporal bone resection

Tumors primarily originating from the ear canal or tympanomastoid compartment are generally managed with some type of temporal bone resection. The most common form of this procedure and the only one that affords the possibility of en bloc tumor removal is lateral temporal bone resection (LTBR), which involves radical resection of the entire ear canal (bony and membranous), tympanic membrane, and underlying malleus manubrium in a single self-contained specimen ( Fig. 1 ). Extensive tumors that invade the middle ear or mastoid may be treated with more aggressive surgery in the form a subtotal temporal bone resection (STBR), which extends the LTBR to include the ossicular chain, otic capsule, facial nerve, and all bone overlying the adjacent middle and posterior cranial fossa dura such that the stump of the internal auditory canal and bone of the petrous apex constitute the deep base of the surgical bed ( Fig. 2 ). Although it is possible to achieve complete tumor resection via STBR, the nature of this procedure necessitates that it is undertaken at least in part by piecemeal dissection thereby clouding the status of surgical margins. Total or radical temporal bone resection involves further extension of STBR to include the carotid artery and jugular bulb-sigmoid, but this procedure is rarely indicated. Finally, each of these procedures may be given the prefix designation “extended” to include concurrent resection of additional adjacent structures such as the temporomandibular joint or styloid process.

Lateral temporal bone resection ( right ear ) involves en bloc resection of the bony and membranous external auditory canal, tympanic ring, tympanic membrane, and malleus manubrium. If properly executed, the undersurface of the tympanic membrane should be intact as the specimen is rotated out of the surgical field and separated from the temporomandibular joint capsule.

Extended subtotal temporal bone resection. ( A ) Subtotal temporal bone resection ( left ear ) involves expansion of lateral temporal bone resection to include resection of the inner ear and facial nerve and removal of all bone off the middle cranial fossa (MCF) and posterior cranial fossa (PCF) dura. At the end of the resection, the petrous apex (PA), jugular bulb (JB), internal auditory canal (IAC), internal carotid artery (ICA), and membranous Eustachian tube (ET). The designation extended is given here because the resection also included removal of the mandibular condyle and drilling out of the glenoid fossa. ( B ) Subtotal temporal bone resection ( left ear ) can also be extended to include resection of the sigmoid sinus (SS) and jugular bulb if needed. SPS, superior petrosal sinus.

Petrous apicectomy and infratemporal fossa exposure

In some instances, surgery requires extended anterior exposure into the petrous apex and infratemporal fossa beyond what is afforded by the standard temporal bone resection techniques. Examples include cases that require mobilization of the intrapetrous carotid artery, tumors invading the pterygoid plates and musculature, and tumors with a significant inferior petrous apex component along the inferior petrosal sinus. In such instances, a lateral skull base approach to the infratemporal fossa is required (Fisch type B or C). For malignant tumors, these approaches usually begin with blind sac closure of the ear canal with subtotal petrosectomy or with some form of temporal bone resection as deemed necessary. The zygomatic arch is released via osteotomies (later reset with plates or permanently removed if a bulky free flap reconstruction is planned) so that the temporalis muscle can be reflected inferiorly. The glenoid fossa is exposed either by mandibular condylectomy or by disarticulation of the temporomandibular joint, yet the author’s strong bias is to resect the condyle because the exposure afforded by disarticulation in children is limited by comparison and the long-term impact of condylectomy on mastication is not overwhelming. The soft tissue approach is finalized as the membranous Eustachian tube is transected.

Infratemporal fossa approaches allow the surgeon to perform a complete anterior petrosectomy progressing from lateral to medial without the need for brain retraction. After the glenoid fossa is drilled out, bone removal proceeds anterior and medial with sequential division of the middle meningeal artery and mandibular branch of the fifth cranial nerve. Last, broad access to the entire intrapetrous internal carotid artery is afforded up to foramen lacerum, as this is the chief advantage of this approach. Dissection continues medially if dissection of the pterygoid plates and lateral nasopharyngeal wall is required (constituting transition from Fisch type B to a Fisch type C approach).

Some malignant tumors isolated within the petrous apex may be approached in a way that preserves the ear canal and hearing mechanism. In these instances a preauricular approach to the infratemporal fossa (Fisch type D) is possible, with the caveat that exposure afforded by this technique is considerably more narrow and that the child will have a lifetime requirement for a tympanostomy tube if the membranous Eustachian tube is violated. Alternatively, if tumor dissection does not require full carotid mobilization and the inferior petrous apex is uninvolved, a subtemporal approach (extended middle cranial fossa) can provide excellent exposure. Although a subtemporal approach may require slight retraction of the temporal lobe, it avoids the significant morbidity associated with violation of the ear canal, otic capsule, temporomandibular joint, and mandibular branch of the fifth cranial nerve.

Fisch partial mastoidotympanectomy

Some malignant tumors of the parotid and upper cervical lymph nodes that lie within the retromandibular fossa and poststyloid space can secondarily invade the inferior aspect of the temporal bone while sparing involvement of the external auditory canal. Such cases are ideal candidates for what has been described by Fisch and Mattox as partial mastoidotympanectomy. This approach involves the sequence of intact canal wall mastoidectomy, decompression of the distal aspect of the mastoid segment of the facial nerve, amputation of the mastoid tip from the digastric muscle, and resection of the inferior tympanic bone and associated styloid base ( Fig. 3 ). This final step includes elevation and preservation of the membranous external auditory canal followed by a drill out of the tympanic bone anterior to the facial nerve; this dissection extends just inferior to the tympanic ring and just lateral to the jugular bulb. Drilling of the styloid base augments medial exposure to the deep lobe of the parotid gland and the anterior aspect of the stylomastoid foramen. In doing so, the styloid process and muscular attachments are released for en bloc resection with the tumor specimen if desired. This approach greatly aids identification of the proximal extratemporal aspect of the facial nerve when bulky tumor is present and also provides a proximal margin for facial nerve grafting in cases in which tumor invasion necessitates nerve sacrifice. In the author’s experience, it is critical to provide bulky inferior soft tissue support of the preserved membranous external auditory canal during the reconstructive phase in order to avoid postoperative canal breakdown and canal-mastoid fistula.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Early Practice
2. Imaging Innovations in Temporal Bone Disorders
3. Nonparaganglioma Jugular Foramen Tumors
4. Cholesterol Granuloma and Other Petrous Apex Lesions

Stay updated, free articles. Join our Telegram channel

Join