Bilateral Parotid Gland Agenesis in Treacher Collins Syndrome: A Case Report

Head and Neck Clinic

A 20-year-old woman visited the department of otorhinolaryngology—head and neck surgery of our hospital with postprandial pain and swelling in the left submandibular area. The patient’s medical history was unremarkable, other than plastic surgery for cosmetic reasons 2 years prior. Upon intraoral examination, a proximally located stone, approximately 1 cm in size, was noted at the left side of the mouth floor. In computed tomography (CT) scan, a 0.6 cm × 0.6 cm round calcified lesion was located in close proximity to the left submandibular gland. Further, we found that the patient exhibited additional craniofacial anomalies, including bilateral parotid gland agenesis and hypoplasia of the zygomatic bone (Figure 1). Salivary gland scintigraphy was performed to confirm the presence of accessory or ectopic parotid gland tissue. Salivary gland scintigraphy showed that neither of the parotid glands could be imaged; moreover, the submandibular glands exhibited relatively normal concentrating function on both sides and normal excretory function on the right side. However, there was decreased excretory function on the left side (Figure 2). The absence of both papillae of Stenson ducts was observed by additional intraoral examination. To confirm the presence of genetic abnormality, we obtained her preoperative photos (prior to plastic surgery) from the plastic surgeon. Through these photos, we determined that she had multiple facial dysmorphic features, including cheek depression, zygomatic hypoplasia on both sides, a bird-like face, retrognathia, and depression of the nasal tip. Based on previous facial features, we suspected Treacher Collins syndrome (TCS), which was genetically confirmed by TCOF1 gene mutation. The sialolith close to the left submandibular gland, which made the patient uncomfortable, was removed by a transoral approach. Furthermore, genetic counseling for TCS was performed.

Figure 1.

Findings of computed tomography (CT) scans. Axial (A) contrast-enhanced CT image reveals a 0.6 cm × 0.6 cm round, calcified lesion in close proximity to the left submandibular gland (black arrow head). Axial (B and C) and coronal (D) CT images reveal the absence of both parotid glands (white arrow heads) and hypoplasia of zygomatic bone (white arrows).

Figure 2.

Findings of technetium-99m pertechnetate salivary gland scintigraphy. Salivary gland scintigraphy shows that the radiotracer is not visible either after administration state of sialogogue (A) or washout state of radiotracer after administration of sialogogue (B) in both the parotid glands. The submandibular glands exhibited relative normal concentrating function on both sides and normal excretory function on the right side but decreased excretory function on the left side.

The parotid glands develop from the ectodermal lining. So, agenesis of the parotid glands is usually associated with other ectodermal structural abnormalities and orofacial defects. Unilateral or bilateral agenesis of the parotid glands is an unusual congenital clinical manifestation, which can present with the absence of other major salivary glands or with additional developmental anomalies. ¹ In a literature review, we found that agenesis of parotid glands has been reported in association with various genetic diseases, such as Down syndrome, Klinefelter syndrome, Levy-Hollister syndrome, and lacrimo-auriculo-dento digital syndrome. ^{1 –4} Even more rarely, it can occur in patients who exhibit no other abnormalities. ^{5 –7} Notably, we experienced a rare case of incidental bilateral agenesis of the parotid glands. Through this discovery, we found that the patient demonstrated features of TCS.

Treacher Collins syndrome is believed to be caused by a change in the TCOF-1 gene on chromosome 5, which affects facial development. The clinical features of the disorder are highly variable, with symptoms ranging from mild to severe. Characteristic features of TCS mainly affect the head and face; these include micrognathia, malformed or absent ears, conductive hearing loss, downward-sloping eyes, drooping of the lateral lower eyelids, underdeveloped zygoma, and cleft palate. In a study of 21 individuals with TCS, dysplasia or aplasia of the major salivary glands was observed in half of the TCS individuals. No glandular tissue was observed in 4 of the cases, while dysfunction of the salivary glands was observed in most cases. However, there was no case that solely consisted of bilateral agenesis of the parotid glands. ⁸

In this case, the patient only complained of postprandial pain and swelling in the left submandibular area because of sialolith without xerostomia. If we had not ordered an imaging test or had not reviewed every image carefully, it would have been difficult to diagnose bilateral agenesis of parotid anomalies in our case because of the absence of symptoms associated with salivary gland dysfunction. Additionally, we would not have been able to confirm her diagnosis of TCS.

In the present case, we have learned that bilateral agenesis of the parotid glands can be observed in an individual with TCS. Moreover, it should be considered that bilateral agenesis of the parotid gland may frequently occur together with various congenital or developmental anomalies. Therefore, if aplasia or dysplasia of the major salivary glands is clinically suspected, CT scan and salivary gland scintigraphy are necessary to clarify the structural or functional abnormalities of the major salivary glands.