Paranasal Mass in a Healthy Male Toddler

Introduction

Myxomas are benign tumors that are mesenchymal in origin. These tumors most commonly occur in the myocardium but can also arise in facial structures, particularly in the maxilla and mandible. However, head and neck myxomas are exceedingly rare in children, generally occurring in adolescents and adults.^1,2 In a review of 15 cases of maxillofacial myxoma in infants, the maxilla was affected without mandible involvement in any of the cases. ² This is different than the pattern seen in older children and adults where the mandible is more commonly affected. ³ Although they are benign, myxomas tend to have insidious growth with significant local invasion. Due to the difficulty of complete excision, the recurrence rate is high.^1,2

We present a case of a maxillary myxoma in a toddler who presented with a painless paranasal mass that grew in size over the course of about 1 month. The patient’s course was atypical for more common pediatric differential diagnoses, such as infection, prompting imaging, and eventual surgery to remove the mass.

Case Report

A previously healthy 15-month-old male was admitted to a general pediatrics service because of a left-sided nasal mass. Mom reported first noticing a bump to the left side of the patient’s nose 3 weeks ago. The patient initially presented to an urgent care 2 weeks prior to this admission due to left eye drainage and crusting for which he was prescribed gentamicin eye drops. Mom denied any further eye drainage after good compliance with the gentamicin eye drops but reported that the bump had increased in size. She denied that the area had been erythematous or with drainage, and the patient did not appear to experience pain when the area was touched. The patient had otherwise been well with no fevers, fussiness, congestion, respiratory distress, decreased oral intake, vomiting, or change in gait.

On physical examination, his weight was at the 50th percentile for age, and his height was at the 56th percentile for age. There were no recent changes in percentiles for growth. His temperature was 98.8 °F (37.1 °C), blood pressure was 113/69, heart rate was 128 beats/min, and respirations were 32 breaths/min. He did appear to have increased fussiness during the entirety of the physical exam. There was a 2 × 1-cm fixed and firm subcutaneous mass in the left nasoalar crease extending superiorly to the medial canthus of the left eye with no overlying erythema, warmth, drainage, or fluctuance on palpation. The patient did not have increased distress with palpation of the mass. He tracked objects appropriately. His lungs were clear to auscultation. The cardiovascular examination revealed a regular heart rate and rhythm with normal S1 and S2 and no murmur. His abdomen was nondistended, soft, and nontender with no palpable organomegaly or masses. A CBC with differential was obtained on admission and was remarkable for thrombocytosis at 547 000/µL ([547 × 10⁹/L] × 10⁹/L).

Both pediatric otolaryngology (Ear, Nose, and Throat [ENT]) and ophthalmology were consulted and recommended a computed tomography (CT) scan with contrast. The CT scan demonstrated a multiloculated, expansile, and osteolytic mass arising from the left maxillary bone with partial involvement of the left nasal bone (Figure 1). A magnetic resonance imaging (MRI) without and with contrast was subsequently obtained for further evaluation and surgical planning. This mass exhibited T1 hypointense and T2 hyperintense signals. The mass appeared to arise from the maxilla and extended into the anterior left maxillary sinus. There was no intra-orbital or intracranial extension of the mass, and teeth were intact. Patient underwent incisional biopsy with ENT during this admission with a preliminary pathological diagnosis. The final diagnosis was obtained after patient underwent removal of the mass by ENT 1 month after this admission.

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Figure 1.

Axial contrast-enhanced bone window CT image shows a left maxillary multiloculated, expansile, and osteolytic lesion that partially involves the left nasal bone, without intranasal extension (arrows). CT indicates computed tomography.

Histologic examination of the excision specimen demonstrated a circumscribed mesenchymal neoplasm, partially delimited by woven bone (Figure 2A), composed of spindled and stellate cells arranged in sheets and fascicles (Figure 2B), possessing variable amounts of amphophilic cytoplasm, round to elongate nuclei, vesicular chromatin, and distinct nucleoli (Figure 2C). Tumor cells were set in a myxoid and fibrous stroma with occasional slit-like vessels. Occasional bi- or multinucleated stellate cells were present. Mitotic activity was rare, and necrosis was absent. Immunohistochemistry for β-catenin showed diffuse, strong expression in tumor cell nuclei (Figure 2D), as previously reported. ⁴

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Figure 2.

A, The tumor was circumscribed and partially surrounded by woven bone (×40). B, Spindled and stellate tumor cells were arranged in sheets and fascicles in a myxoid and fibrous stroma (×100). C, Tumor cells possessed amphophilic cytoplasm, round to elongate nuclei, vesicular chromatin, with occasional multinucleated stellate cells (×200). D, Immunohistochemistry for β-catenin was diffusely positive in tumor cell nuclei (×200).

Discussion

As was the case with our patient, the most common presentation of maxillofacial myxomas is an insidiously growing, painless mass. They are usually asymptomatic, but depending on their extension, patients can also present with the following symptoms: eye tearing or pain, diplopia, nasal congestion, respiratory distress, tooth pain, and difficulty with chewing.^2,5 Masses can enlarge over weeks, months, and even years, and patients can present anytime during that duration. ⁵

Patients usually undergo a CT scan for an initial diagnostic evaluation. Myxomas generally appear as a multilocular, lucent, expansile, and well-circumscribed mass. They can cause bone remodeling or erosion. Larger myxomas have been described as having a “soap bubble” appearance.^5,6 Magnetic resonance imaging is usually the next step in imaging evaluation, allowing for tissue characterization and assessment of disease extension for surgical planning. Myxomas have less of a standardized appearance on MRI and have been described as having variable T1- and T2-weighted signal intensity. In general, they are usually T1-hypointense, T2-hyperintense, and demonstrate enhancement with contrast, likely due to the collagen component. ⁶ On diffusion-weighted imaging, myxomas show increased diffusivity. This could help differentiate from malignant neoplasms, which usually exhibit reduced diffusivity (ie, restricted diffusion), due to a high nuclear-cytoplasmic tumor cell ratio. ⁴

Histologically, myxomas are composed of basophilic, stellate cells that have long and branching cytoplasmic projections. Those cells are contained in an amorphous, avascular, and myxoid stroma that consists of hyaluronic acid and chondroitin sulfate.^5,7 Myxomas may resemble other tumor types, including rhabdomyosarcomas, which can be differentiated with histochemical stains. ⁷

The differential diagnosis for a tumor presenting in the maxillofacial region is broad due to the number of structures and their various germ-cell origins. Therefore, this discussion will focus on the differential diagnosis for a tumor presenting in the maxilla. Because of the unique location of these tumors, they are often classified as either odontogenic (ie, tissues that give rise to teeth) or osteogenic, also called non-odontogenic. ⁷

The 2 most common odontogenic tumors are ameloblastomas and odontomas. Ameloblastomas arise from the epithelium of the dental lamina that specifically give rise to enamel and are usually benign. About 80% of ameloblastomas occur in the mandible and 20% occur in the maxilla. ⁸ Odontomas are hamartomas, consisting of both epithelial and mesenchymal dental structures. They are associated with impacted or unerupted teeth or teeth that have experienced trauma or infection, and they commonly occur in Gardner syndrome, a subtype of Familial adenomatous polyposis. ⁹

Non-odontogenic tumors are further classified based on their benign or malignant nature. Benign tumors include giant cell tumor, osteoma, aneurysmal bone cyst, or myxoma. Malignant tumors include osteosarcoma, lymphoma, and sarcoma. When a myxoma is suspected, it is important to ensure that it is not a sarcoma, specifically an embryonal rhabdomyosarcoma. Both tumors can arise in the same locations and have similar pathology but are treated vastly differently. Rhabdomyosarcomas require multimodality therapy consisting of surgery, chemotherapy, and radiation.^7,10

Although mortality is low in the pediatric population, morbidity ranges depending on the location of the mass and how locally aggressive the tumor is. These tumors can result in the destruction of bone leading to compromise of structures in various systems including ocular, airway due to nasal obstruction, and digestive due to erosion into oral cavity, but excision can also lead to disfigurement and disability. Complete excision is curative but can be difficult. Depending on the areas involved and their proximity to vital structures such as vascularity, a partial excision with a watch-and-wait approach can be used, but recurrence is almost inevitable. Many patients will require extensive surgeries or multiple surgeries in order to completely excise the tumor. Reports ranging from partial maxillectomy all the way to radical maxillectomy with orbital exenteration have been described in the literature.^1,2,10

Our patient had a follow-up MRI 1 month after removal of mass, which demonstrated areas concerning for residual disease in ethmoid and maxillary sinuses. An MRI obtained for further surgical planning about 6 months after the removal of the mass was unremarkable, and the areas previously concerning for residual disease were likely postsurgical and/or inflammatory changes. Clinically, he continues to do well with normal growth and development and without any ocular or respiratory symptoms.

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