Lingual osseous choristoma of the posterior tongue: A case report

Introduction

Lingual osseous choristoma is a rare, benign condition where mature bone tissue is found in an ectopic location of the tongue. Since its first description in 1913 by Monserrat as a “lingual osteoma,” ¹ a few more than 100 cases have been documented in the existing literature. ² Proper diagnosis is crucial to distinguish it from other lingual masses such as fibromas, hemangiomas, and osseous dysplasias. ³

Due to the rarity of this diagnosis, it is important for the clinician and pathologist to be exposed to this pathology through case reports, as they may encounter it in practice, but are unlikely to have had a clinical exposure to it in training. This paper will present a case of posterior lingual osseous choristoma, discussing its clinical presentation, diagnostic approach, treatment, and outcomes.

Patient information

A 45-year-old woman was referred to the Otolaryngology clinic of the CIUSSS de l’Estrie – CHUS for evaluation of a mass located on the left posterior dorsal surface of her tongue. The lesion had been initially identified incidentally during a routine dental examination several months prior and had demonstrated slow, progressive growth. The patient denied any associated symptoms, including pain, dysphagia, odynophagia, bleeding, or foreign body sensation.

Clinical findings

On physical examination, a well-circumscribed, firm, whitish lesion measuring ~0.6 × 0.5 × 0.3 cm was observed on the left posterior dorsal aspect of the tongue. The lesion was non-ulcerated, non-tender, and appeared sessile. No cervical lymphadenopathy was noted. The clinical appearance suggested a benign process, with differential diagnoses including fibroma and an irritated circumvallate papilla.

Timeline

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Time point	Clinical event
Several months prior	Lesion incidentally noted during dental examination
Progressive course	Slow enlargement without symptoms
Initial consultation	Evaluation in otolaryngology clinic Excisional biopsy under local anesthesia
Postoperative period	Uneventful recovery
2-Year follow-up	No evidence of recurrence

Diagnostic assessment

The initial clinical evaluation suggested a benign lesion; however, its exact nature remained uncertain due to its nonspecific appearance. An excisional biopsy was therefore performed to establish a definitive diagnosis.

Histopathological examination revealed mature cortical bone within the submucosal tissue of the tongue, covered by stratified squamous epithelium without atypia (Figures 1 and 2). These findings were consistent with a diagnosis of lingual osseous choristoma.

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Figure 1.

Hematoxylin and eosin stain, 4× magnification, demonstrating a stratified squamous epithelium without atypia overlying submucosal osseous tissue.

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Figure 2.

Hematoxylin and eosin stain, 10× magnification, demonstrating mature cortical bone within the choristoma.

The differential diagnosis included fibroma, hemangioma, osseous dysplasia, and other benign oral lesions. The rarity of lingual osseous choristoma and its resemblance to more common conditions represented the main diagnostic challenge in this case.

Therapeutic intervention

A complete excisional biopsy was performed in an outpatient setting under local anesthesia. The lesion was entirely removed without complications. No additional medical or surgical treatment was required, and no modifications to the intervention were necessary.

Follow-up and outcomes

The patient’s postoperative course was uneventful. At follow-up visits, she remained asymptomatic, with no evidence of recurrence or complications. At 2 years post-excision, clinical examination confirmed complete healing and absence of lesion recurrence. The patient adhered fully to follow-up recommendations, and no adverse or unexpected events were reported.

Discussion

The term “choristoma” refers to the presence of histologically normal tissue in an ectopic location, reflecting a developmental anomaly rather than a true neoplasm. ⁴ Depending on the tissue of origin, choristomas may consist of glial, cartilaginous, gastrointestinal, thyroidal, or osseous elements. ⁵ Among these, osseous choristoma represents a rare entity characterized by mature bone formation within soft tissues, most frequently occurring in the head and neck region, particularly within the tongue.^4,6

Lingual osseous choristomas most commonly arise on the posterior dorsal surface of the tongue, often near the foramen caecum.^2,7 This consistent anatomical distribution has been well documented and supports hypotheses related to embryologic development.^2,8 Epidemiologically, these lesions demonstrate a marked female predominance and are most frequently diagnosed in patients in the second to fourth decades of life.^1,7

Despite these consistent clinical features, the etiopathogenesis of lingual osseous choristoma remains incompletely understood.^2,7 Two principal theories have been proposed, each with inherent limitations.^1,9

The developmental theory, initially proposed by Monserrat, suggests that these lesions originate from embryologic remnants of the branchial arches.^2,10 The posterior third of the tongue derives primarily from the third branchial arch, which also contributes to the formation of osseous structures such as portions of the hyoid bone. ⁸ It has therefore been hypothesized that pluripotent mesenchymal cells or residual osseous precursors may persist in the tongue and subsequently differentiate into mature bone tissue.^7,8 This theory is supported by the frequent localization of these lesions near the foramen caecum, a known embryological fusion site.^2,8 However, it does not fully explain cases occurring outside this region or those identified later in adulthood. ⁷

The reactive or post-traumatic theory proposes that chronic irritation, repetitive microtrauma, or local inflammation may induce osseous metaplasia within the lingual soft tissues.^7,10 Given the dynamic nature of the posterior tongue, which is subjected to continuous mechanical stress from swallowing and speech, this mechanism is biologically plausible.^7,10 Nonetheless, this hypothesis is limited by the absence of a clear history of trauma or chronic irritation in many reported cases, including the present one.^2,7 Furthermore, the presence of well-organized lamellar bone with Haversian systems suggests a structured developmental process rather than a purely reactive phenomenon.^5,6 Taken together, these observations suggest that lingual osseous choristoma may represent a heterogeneous condition involving both developmental and reactive mechanisms, although definitive conclusions remain limited due to the rarity of the entity.^2,7

From a clinical perspective, lingual osseous choristoma presents a diagnostic challenge due to its nonspecific appearance.^2,5 These lesions are typically described as firm, well-circumscribed, sessile or pedunculated nodules of the posterior tongue.^2,7 As a result, the differential diagnosis is broad and includes a variety of benign and, less commonly, malignant entities.

Benign soft tissue lesions such as fibromas are among the most common clinical considerations due to their similar presentation as well-defined mucosal nodules. ⁵ Other lesions such as granular cell tumors, neurofibromas, or schwannomas may also be considered based on morphology. Papillomas usually have a characteristic cauliflower-like appearance. Vascular lesions, including hemangiomas, are usually clinically distinguished by their compressibility and characteristic coloration. Hypertrophic or prominent circumvallate papillae may also mimic small lesions of the posterior tongue, particularly when inflamed. ⁵ Lesions located near the foramen caecum require particular attention, as ectopic thyroid tissue (lingual thyroid) must be considered due to its potential functional significance. ⁵ Additionally, calcified lesions such as peripheral osteomas or other forms of osseous proliferation, although rare in this location, should be considered in the differential diagnosis.^3,10

Malignant lesions such as minor salivary gland tumors are also possible, although less frequently found on the tongue. Squamous cell carcinoma is unlikely in the absence of rapid growth, ulceration, pain, or lymphadenopathy, but should still be considered in atypical presentations. ⁵

In this context, clinical examination alone is insufficient to establish a definitive diagnosis. In the present case, the lesion was small, asymptomatic, and clinically suggestive of a benign process, and therefore, no preoperative imaging was performed. This approach is consistent with current practice, as imaging is not routinely indicated for small, well-circumscribed lesions of the oral cavity without concerning features. ⁵ When performed, imaging modalities such as computed tomography may demonstrate a well-defined hyperdense lesion corresponding to calcified tissue, which can assist in diagnosis in selected or atypical cases.^6,11

Histopathological examination remains the gold standard for diagnosis, allowing definitive identification of mature lamellar bone within the submucosa beneath normal stratified squamous epithelium.^1,5 This is essential not only for confirming the diagnosis but also for excluding other entities, including ectopic thyroid tissue or calcified neoplasms.^2,5

Surgical excision is the treatment of choice and is both diagnostic and curative.^6,11 Recurrence is exceedingly rare following complete excision, and long-term prognosis is excellent.^6,11 In the present case, the patient experienced an uneventful postoperative course, with no evidence of recurrence after 2 years of follow-up, consistent with previously reported outcomes.^6,11

Overall, this case highlights the importance of maintaining a broad differential diagnosis when evaluating posterior tongue lesions and reinforces the central role of histopathological assessment in establishing a definitive diagnosis.

Conclusion

Lingual osseous choristoma is a rare benign lesion that should be considered in the differential diagnosis of posterior tongue masses. Definitive diagnosis relies on histopathological examination, and surgical excision provides an effective and curative treatment. Awareness of this entity can help clinicians avoid misdiagnosis and ensure appropriate management.

Patient perspective

After discussion with the patient at the 2-year follow-up mark, she confirms that this incidental finding by the dentist did not have any significant symptomatic implications. She was satisfied with the excision biopsy being done in the clinic and did not report any morbidity to this day.