Oropharyngeal cartilaginous choristoma: a systematic review of the literature with novel clinical insights

INTRODUCTION

Choristoma, derived from the Greek word 'choristos' meaning 'separated,' is defined as a tumour-like mass consisting of histologically normal tissue present in an anatomical location where it is not normally found.¹ The term was first introduced by Krolls and colleagues in 1971 to describe tumour-like growths of microscopically normal tissue in an unusual location, distinguishing these lesions from hamartomas (disorganised overgrowth of indigenous tissues) and teratomas (true neoplasms composed of multiple germ layer derivatives).

Among the various types of choristomas identified in the head and neck region, cartilaginous choristoma represents one of the rarest and most intriguing entities, characterised specifically by the ectopic presence of mature hyaline cartilage. The first description of cartilaginous tissue in the oral soft tissues is attributed to Zahn in 1885, with Berry reporting the first case of fibrochondroma of the tongue in 1890.^2,3 Since these seminal reports, cartilaginous choristomas have been documented at various sites throughout the head and neck, including the tongue (most commonly), buccal mucosa, gingiva, soft palate, and tonsil.^4,5

The oropharynx is a critical anatomical subsite of the upper aerodigestive tract, bounded superiorly by the soft palate, inferiorly by the hyoid bone, and comprising the palatine tonsils, tonsillar fossae, base of tongue, and posterior and lateral pharyngeal walls. The clinical presentation of oropharyngeal masses varies considerably depending on their size, location, and rate of growth, ranging from completely asymptomatic incidental findings to significant airway obstruction, dysphagia, and voice changes. The rarity of cartilaginous choristomas in this location, combined with their non-specific clinical presentation, frequently leads to diagnostic confusion with more common oropharyngeal pathologies such as squamous cell carcinoma, lymphoma, benign salivary gland tumours, and infectious or inflammatory processes.

This systematic review was undertaken with the primary objectives of comprehensively cataloguing all reported cases of oropharyngeal cartilaginous choristoma in the English-language literature, analysing their demographic, clinical, radiological, and histopathological characteristics, and presenting a novel case of lateral pharyngeal wall cartilaginous choristoma to contribute to the limited body of evidence on this rare entity.

METHODS

Protocol and registration

This systematic review was conducted in accordance with the preferred reporting items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement guidelines. The review protocol was not prospectively registered given the anticipated small number of eligible studies and the nature of the research question (rare case series/reports only).

Search strategy

A comprehensive literature search was performed across five electronic databases: PubMed/MEDLINE (National Library of Medicine), Scopus (Elsevier), Web of Science Core Collection (Clarivate Analytics), Embase (Elsevier), and Google Scholar. The search was conducted from database inception to June 23, 2026, with no language restrictions applied during the initial screening phase.

The following search string was adapted for each database: ("choristoma" or "cartilaginous choristoma" or "chondroid choristoma" or "osseous choristoma" OR "osteocartilaginous choristoma" or "heterotopic cartilage" or "ectopic cartilage") and ("oropharynx" or "oropharyngeal" or "tonsil" or "tonsillar" or "palatine tonsil" or "pharyngeal wall" or "soft palate" or "tonsillar fossa" or "Waldeyer's ring"). Reference lists of all included articles and relevant review articles were manually screened to identify additional eligible studies (backward citation searching).

Eligibility criteria

Inclusion criteria

Studies were eligible for inclusion if they reported primary data on cartilaginous, osteocartilaginous, or chondroid choristomas located within the anatomical boundaries of the oropharynx. Case reports, case series, and observational studies (including prospective analyses of tonsillectomy specimens) were eligible. Studies reporting sufficient data on patient demographics, clinical presentation, anatomical site, histopathological diagnosis, and treatment were preferred.

Exclusion criteria

Studies were excluded if they reported choristomas located exclusively outside the oropharynx (e.g., tongue proper, buccal mucosa, gingiva, floor of mouth, nasopharynx, hypopharynx, or middle ear). Review articles, editorials, letters to the editor without original data, conference abstracts, and non-English language publications with insufficient extractable data were also excluded.

Study selection and data extraction

All records retrieved from the database searches were imported into reference management software, and duplicate records were removed. Two independent reviewers screened all titles and abstracts for potential eligibility. Full-text articles of potentially eligible records were retrieved and independently assessed. Disagreements were resolved through discussion and consensus, with arbitration by a third reviewer if necessary. A standardised data extraction form was used to collect: first author, year, country, study design, number of cases, patient age and sex, anatomical site, clinical presentation, duration of symptoms, lesion size, imaging findings, treatment modality, histopathological features, follow-up duration, and recurrence status.

Quality assessment

Given that the majority of included studies were case reports and case series, formal quality assessment using the Newcastle-Ottawa Scale or Cochrane Risk of Bias tools was not applicable. The methodological quality of each included study was assessed using a modified version of the Joanna Briggs Institute (JBI) critical appraisal checklist for case reports.

Data analysis

Given the anticipated heterogeneity and small number of cases, a formal meta-analysis was not planned. Descriptive statistical analysis was performed on all extracted data. Categorical variables were summarised as frequencies and percentages, while continuous variables were reported as means with ranges. All analyses were conducted using Microsoft Excel (version 16.0) and Python (version 3.12).

RESULTS

Literature search and study selection

The systematic database search yielded a total of 1,847 records: PubMed/MEDLINE (n=623), Scopus (n=412), Web of Science (n=298), Embase (n=267), and Google Scholar (n=247). An additional 23 records were identified through backward citation searching. After removal of 308 duplicate records, 1,562 unique records remained for title and abstract screening. Of these, 1,489 records were excluded at the title/abstract stage.

Seventy-three full-text articles were assessed for eligibility, of which 55 were excluded: 28 reported lesions at non-oropharyngeal sites (tongue n=18, buccal mucosa n=5, gingiva n=3, floor of mouth n=1, nasopharynx n=1), 15 reported non-cartilaginous choristoma types, 8 were review articles or editorials without primary data, and 4 contained insufficient extractable data. Eighteen studies met all inclusion criteria and were included in the qualitative synthesis. The PRISMA 2020 flow diagram is presented in Figure 1.

Demographic and anatomical characteristics

A total of 28 discrete cartilaginous choristoma lesions were identified across the included studies (including the present unpublished case). The mean age at presentation was 28.6 years (range 4–50 years), with the majority of patients (n=16, 57.1%) presenting between the second and fourth decades of life. The male-to-female ratio was approximately 1.2:1 (15 males, 13 females), indicating no strong sex predilection, in contrast to the female predominance (approximately 70%) reported for lingual cartilaginous choristomas.

The palatine tonsil was by far the most common site, accounting for 24 lesions (85.7%). The lateral pharyngeal wall was the second most common site (n=2, 7.1%), followed by the tonsillar fossa/posterior tonsillar pillar (n=2, 7.1%). Bilateral tonsillar involvement was reported in 4 cases (14.3% of tonsillar lesions).

Clinical presentation and radiological features

The most common presenting symptom was recurrent tonsillitis (n=18, 64.3%), followed by dysphagia (n=6, 21.4%), sore throat or odynophagia (n=5, 17.9%), snoring or sleep-disordered breathing (n=3, 10.7%), and halitosis (n=2, 7.1%). Two patients (7.1%) presented with incidentally discovered asymptomatic masses. Duration of symptoms ranged from 20 days to 4 years (mean ~14 months).

Radiological imaging was performed in only a minority of cases (n=6, 21.4%). CT was the most commonly used modality (n=4), typically demonstrating a well-circumscribed, non-enhancing soft tissue mass with punctate calcifications. MRI (n=2) showed intermediate T1 and variable T2 signal intensity with no contrast enhancement. The radiological differential diagnosis is broad and non-specific.

Treatment and outcomes

Surgical excision was the treatment modality in all reported cases. Tonsillar lesions were universally treated with tonsillectomy (partial or complete), with the choristoma being an incidental histopathological finding in the majority of cases. Extra-tonsillar lesions (lateral pharyngeal wall, tonsillar fossa) were excised via transoral approach under general anaesthesia. No cases of recurrence were documented in the follow-up period (range 3 months to 2 years). No malignant transformation has been reported in any oropharyngeal cartilaginous choristoma in the literature.

Incidence data from prospective studies

Two prospective studies provided valuable epidemiological data. Erkilic et al reported a 3% incidence of cartilage in routine tonsillectomy specimens.⁶ Ciris et al conducted the largest prospective analysis to date, examining 2,355 tonsillectomy specimens over a 16-year period, and identified cartilaginous choristomas in 141 patients (5.99% incidence), with a total of 155 individual choristomas detected.⁷ Bilateral involvement was observed in 14 patients, and multifocal lesions in 20 patients. No association with primary malignancy was identified.

Table 1 provides summary of key demographic, epidemiological, and clinicopathological findings from the systematic review of 18 studies and 28 discrete oropharyngeal cartilaginous choristoma lesions. Table 2 provides a comprehensive side-by-side comparison of all 24 reported cases of oropharyngeal cartilaginous choristoma included in this systematic review, presented in chronological order of publication.

CC=cartilaginous choristoma.

Clinical presentation

A 25-year-old female patient presented to the Otorhinolaryngology outpatient clinic with a 10-month history of a slowly progressive swelling in the throat associated with difficulty in swallowing. She reported a sensation of a foreign body in the throat and intermittent dysphagia to solids. She denied any dyspnoea, hoarseness, otalgia, or constitutional symptoms such as fever, weight loss, or night sweats. There was no relevant past medical, surgical, or family history.

Physical examination

General examination was unremarkable. There was no palpable cervical lymphadenopathy. Oropharyngeal examination revealed a solitary, fleshy, pinkish mass lesion located on the left lateral pharyngeal wall. The mass was firm in consistency, non-tender, and covered by intact stratified squamous mucosa without ulceration, necrosis, or active bleeding. The lesion measured approximately 2×2 cm on visual inspection. Bilateral tonsils appeared normal in size and morphology (Figure 2).

Diagnostic imaging

Flexible naso-endoscopy demonstrated a well-defined pedunculated mass originating from the region of the left Eustachian tube orifice on the lateral pharyngeal wall, with intact overlying mucosa. Contrast-enhanced CT of the neck demonstrated a well-circumscribed, non-enhancing soft tissue lesion measuring 2×2×1.5 cm arising from the left lateral pharyngeal wall, adjacent to the cartilaginous portion of the Eustachian tube. The lesion showed homogeneous attenuation without evidence of bony erosion, calcification, or infiltration into surrounding structures (Figure 3). No cervical lymphadenopathy was identified. The clinical and radiological differential diagnosis included benign salivary gland tumour, neurogenic tumour, fibroma, and choristoma.

Surgical management

Following informed consent, the patient underwent excisional biopsy of the mass under general anaesthesia via a transoral approach. Intraoperatively, the mass was found to be well-circumscribed, firm, and encapsulated, with a broad base attached to the lateral pharyngeal wall mucosa near the Eustachian tube orifice. The lesion was completely excised with adequate margins, including the overlying mucosa and underlying perichondrium. Haemostasis was achieved without the need for reconstruction. The procedure was uncomplicated.

Gross and histopathological findings

Gross examination revealed a nodular, firm mass measuring 2×2×1.5 cm with a smooth, glistening external surface. The cut surface showed a solid, yellowish-white, homogeneous appearance with a firm, cartilaginous consistency.

Histopathological examination of haematoxylin and eosin-stained sections revealed stratified squamous epithelium lining the surface, devoid of cytological atypia, dysplasia, or malignant features. The subepithelial connective tissue showed well-demarcated lobules of mature hyaline cartilage admixed with lobules of mature adipose tissue. The cartilage lobules were composed of mature chondrocytes within lacunae, surrounded by abundant hyaline matrix, without nuclear pleomorphism, hyperchromasia, or increased mitotic activity. Additional histological findings included nerve bundles and small blood vessels within the fibrous stroma. No salivary gland tissue, bone, or malignant components were identified (Figure 4). A diagnosis of cartilaginous choristoma of the oropharynx was established.

Postoperative course

The patient had an uneventful postoperative recovery. Oral feeding was commenced on the first postoperative day, and discharge was on the second postoperative day. Postoperative flexible endoscopy at 2 weeks revealed complete healing of the surgical site with no residual mass. The patient reported complete resolution of dysphagia and foreign body sensation. At 6-month follow-up, there was no evidence of local recurrence and the patient remained asymptomatic.

DISCUSSION

Epidemiology and demographics

This systematic review represents the most comprehensive analysis of oropharyngeal cartilaginous choristomas conducted to date, synthesising data from 18 studies encompassing 28 discrete lesions. The palatine tonsil emerges as the predominant site of involvement, accounting for over 85% of all reported oropharyngeal cartilaginous choristomas. This predilection for tonsillar tissue is likely explained by the complex embryological development of the tonsil from the second pharyngeal pouch, which provides an anatomical substrate for the entrapment of multipotent mesenchymal cells with chondrogenic potential.

The mean age at presentation of 28.6 years and the broad age range (4–50 years) suggest that oropharyngeal cartilaginous choristomas can present across the entire spectrum of age groups. The slight male predominance (M:F ratio 1.2:1) differs from the marked female predominance (~70%) reported for lingual cartilaginous choristomas, suggesting potential sex-related differences in anatomical distribution or pathogenesis.

Pathogenesis and embryology

The precise pathogenesis of cartilaginous choristomas remains incompletely understood. Table 3 summarises the principal proposed embryological hypotheses.

The most widely accepted explanation involves a developmental anomaly during embryogenesis. The palatine tonsil develops in relation to the lateral part of the second pharyngeal pouch, which is lined by endoderm and separated from the surface ectoderm by a layer of mesoderm forming the pharyngeal arches. Any developmental anomaly during this process may result in the entrapment of multipotent mesenchymal cells within the tonsillar tissue, which subsequently differentiate into mature cartilage.^24-28

An alternative hypothesis proposes that extraskeletal proliferation of cartilage in the oral cavity reflects the multipotential nature of primitive mesenchymal cells in this region, which may be stimulated to undergo chondrogenic differentiation by trauma, chronic irritation, or inflammation.^29,30 The high incidence of cartilaginous choristomas in tonsillectomy specimens from patients with chronic recurrent tonsillitis (3–6%) supports the theory that chronic inflammatory stimulation may play a role.¹⁸ The case reported herein, involving the lateral pharyngeal wall in close proximity to the Eustachian tube orifice, raises additional embryological considerations regarding the role of first pharyngeal pouch derivatives.

Clinical presentation and diagnosis

The clinical presentation of oropharyngeal cartilaginous choristomas is highly variable and depends primarily on the anatomical site and size of the lesion. The most common presentation remains recurrent tonsillitis, observed in nearly two-thirds of cases. This association may be coincidental or causal, with the ectopic cartilage potentially serving as a nidus for chronic inflammation or mechanical irritation.

The diagnosis is primarily histopathological. Preoperative clinical and radiological assessment is typically non-diagnostic, as these lesions lack pathognomonic imaging features. The differential diagnosis is broad and clinicians should maintain a high index of suspicion, particularly when evaluating firm oropharyngeal masses in the absence of risk factors for malignancy.

Histopathological features and differential diagnosis

The histopathological diagnosis is straightforward when classic features are present: well-circumscribed lobules of mature hyaline cartilage in an ectopic location, surrounded by a thin perichondrium-like layer of fibrous tissue, with mature chondrocytes lacking cytological atypia or mitotic activity.

The distinction from cartilaginous metaplasia is important: metaplastic cartilage occurs in soft tissues subjected to chronic trauma and is characterised by diffuse calcium deposits, scattered cartilaginous cells in various stages of maturation, and single or clustered foci. In contrast, choristomas demonstrate well-formed mature hyaline cartilage in distinct lobules. Osteocartilaginous choristomas (containing both mature bone and cartilage) represent a histological variant observed in approximately 20% of cases in this review.³¹

Treatment and prognosis

Complete surgical excision is the treatment of choice and is curative in all reported cases. For tonsillar lesions, tonsillectomy (either unilateral or bilateral depending on clinical indication) is both diagnostic and therapeutic. For extra-tonsillar lesions, local excision with adequate margins is recommended. The importance of removing the perichondrium along with the cartilage cannot be overstated, as incomplete excision may theoretically risk recurrence.

The prognosis of oropharyngeal cartilaginous choristoma is excellent. No cases of recurrence were documented in any of the reported cases with adequate follow-up, and no malignant transformation has been described. This benign behaviour is consistent with the nature of the lesion as a developmental anomaly rather than a true neoplasm.

Significance of the present case and limitations

The case reported here is noteworthy for several reasons. First, the lateral pharyngeal wall is an extremely uncommon site, with only one previously reported case involving a similar location.²³ Second, the origin from the region of the Eustachian tube orifice raises unique embryological considerations regarding first pharyngeal pouch derivatives. Third, the size (2×2×1.5 cm) and associated dysphagia distinguish this case from more commonly encountered incidental microscopic tonsillar choristomas.

The principal limitation of this systematic review is the reliance on case reports and small case series, which carry inherent risks of selection bias and publication bias. The majority of included studies had incomplete demographic and follow-up data, precluding definitive conclusions regarding natural history. The heterogeneity of reporting precluded formal meta-analysis.

CONCLUSION

Oropharyngeal cartilaginous choristoma is a rare but clinically significant benign entity that most commonly involves the palatine tonsil, though it can occur at any site within the oropharynx including the lateral pharyngeal wall.

Clinicians and pathologists should maintain a high index of suspicion for cartilaginous choristoma in the differential diagnosis of oropharyngeal masses, particularly when evaluating tonsillectomy specimens or extra-tonsillar lesions with firm consistency and non-specific imaging features. Continued reporting of cases will further elucidate the natural history, optimal management, and long-term outcomes of this rare but important entity.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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