Context: A complex embryological crossroads

Lingual osseous choristoma is an exceptional benign lesion characterized by the presence of mature lamellar bone tissue within the soft tissues of the tongue. Simultaneously, the thyroglossal duct cyst (TDC) represents the most frequent median congenital lesion of the neck, resulting from an incomplete involution of the thyroglossal duct. Although these two entities share a common embryological axis extending from the base of the tongue to the lower cervical region, their synchronous manifestation in the same patient had, until now, never been documented in the scientific literature.

The objective of this study is to report the unique clinical case of a 26-year-old female patient presenting simultaneously with an osseous choristoma of the base of the tongue and a suprahyoid TDC. The authors explore the hypothesis that these two lesions are not clinical coincidences, but dual manifestations of mesenchymal residues along the thyroglossal duct-hyoid bone axis. This presentation highlights the importance of comprehensive imaging of the thyroglossal tract when faced with any posterior lingual osseous mass, in order to rule out a more extensive underlying embryonic pathology.

Design and management protocol

This case report documents the diagnostic and therapeutic strategy for a 26-year-old female patient presenting with a symptomatic posterior lingual mass since adolescence, with worsening dysphagia over the last 4 years. The methodological approach integrated an exhaustive clinical evaluation and a multisite surgical intervention.

The investigation and intervention protocol followed several key steps:

• Multimodal imaging: Performance of a cervical MRI and a facial CT scan with contrast medium to characterize the pedunculated mass of the base of the tongue and identify any extension or synchronous lesion along the thyroglossal tract.
• Combined surgical approach: Under general anesthesia, an endoscopy-assisted intra-oral excision was performed for the lingual lesion. Simultaneously, a transcervical approach allowed the excision of a retro-hyoid cyst with partial segmental resection of the hyoid bone and en bloc removal of the thyroglossal tract over a length of 5 cm.
• Management of intraoperative complications: Immediate repair of a posterior pharyngeal wall breach (due to dense adhesions) via a double-layer closure (mucosal and muscular), secured by the temporary placement of an L-tube.

The final analysis relied on the histopathological examination of the excised tissues to confirm the nature of the osseous choristoma and the thyroglossal duct cyst. Functional recovery, particularly swallowing, was monitored up to 18 months post-intervention.

Clinical and radiological evaluation results

The initial clinical examination of this 26-year-old patient revealed a firm pedunculated mass, covered by intact mucosa, located on the midline of the base of the tongue, near the circumvallate papillae. Magnetic resonance imaging (MRI) and cervical computed tomography (CT) scan highlighted two distinct entities:

• A pedunculated nodular lesion at the base of the tongue, with no signs of muscular invasion.
• A well-circumscribed unilocular cystic lesion, located posterior to the hyoid bone, along the suprahyoid thyroglossal tract.

Surgical and anatomopathological data

The procedure combined an endoscopy-assisted intra-oral approach for the lingual mass and a transcervical approach for the cyst. The authors report the en bloc excision of a thyroglossal tract extending approximately 5 cm upwards, associated with a partial segmental resection of the hyoid bone (modified Sistrunk procedure).

Lesion	Location	Histopathological Observations
Osseous choristoma	Base of the tongue (midline)	Mature lamellar bone tissue located beneath a stratified squamous epithelium.
Thyroglossal duct cyst	Retrohyoid region	Typical histological features of a thyroglossal duct cyst wall.

Clinical follow-up and outcome

Despite dense fibrous adhesion requiring repair of the posterior pharyngeal wall (two-layer suture), postoperative functions were preserved. Evaluation of swallowing function revealed no aspiration or dysphagia. At the 18-month follow-up, clinical results indicate:

• An absence of recurrence at the base of the tongue or in the cervical region.
• A completely intact swallowing function.
• The complete resolution of the foreign body sensation and initial dysphagia.

A common embryonic origin: the nexus of the foramen cecum

This clinical case highlights an exceptional synchronous association: a lingual osseous choristoma and a supra-hyoid thyroglossal duct cyst (TDC) in a 26-year-old female patient. The location of the choristoma, precisely at the foramen cecum, is not incidental. The authors suggest that these two entities could be dual manifestations of mesenchymal remnants along the embryonic axis extending from the base of the tongue to the lower cervical region. This observation reinforces the embryonic hypothesis of the choristoma — the persistence of osteogenic primordia from the hyoid apparatus — rather than simple reactive metaplasia.

The importance of an extensive imaging assessment

The crucial point here is the incidental discovery of the TGDC during the cervical MRI, while the initial complaint only concerned the lingual mass. Without this complete imaging (MRI and CT scan), the suprahyoid cyst would likely have gone unnoticed, risking subsequent infection or airway compromise. Surgical management required a combined approach: endoscopy-assisted intra-oral excision for the choristoma and a modified Sistrunk procedure (segmental resection of the hyoid bone) for the TGDC. The intraoperative pharyngeal defect, caused by dense adhesions, serves as a reminder that even benign lesions can present complex dissection challenges.

Clinical limits and findings

As this is a single case report (n=1), the generalization of this embryological link remains speculative, although appealing. The main limitation lies in the impossibility of definitively proving the pathogenic mechanism. However, the 18-month follow-up without recurrence validates the efficacy of the en bloc resection of the thyroglossal duct combined with the excision of the lingual lesion.

Summary of results

This clinical case reports the simultaneous presence of a lingual osseous choristoma and a thyroglossal duct cyst in a 26-year-old female patient. Treatment by dual surgical excision — intra-oral and transcervical with partial resection of the hyoid bone — resulted in healing without recurrence at 18 months with intact swallowing function.

In concrete terms, for the practitioner:

• Diagnostic vigilance: Faced with any firm mass at the base of the tongue, prescribe complete cervical imaging (MRI or CT scan) to systematically exclude a synchronous thyroglossal duct cyst located on the embryonic migratory axis.
• Embryological axis: Consider these two entities as dual manifestations of residual tissues along the thyroglossal-hyoid tract, which requires a meticulous exploration from the base of the tongue to the cervical region.
• Surgical strategy: Prioritize a combined intervention treating both lesions simultaneously to prevent infectious or compressive risks while ensuring a lasting functional and aesthetic result.

Discovering a mass at the base of the tongue in a young female patient is a classic diagnostic challenge. However, when histology reveals bone where it should not be and imaging unveils a synchronous thyroglossal duct cyst (TGC), the case becomes exceptional. This case study documents for the first time this rare association in a 26-year-old woman, suggesting a common embryological origin along the thyroid migration axis.

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