Primary sinonasal chondroid chordoma in a pediatric patient: a diagnostic challenge

Background Chordomas are rare, malignant tumors typically centered in midline structures such as the clivus and sacrum, with peak prevalence in the fourth decade. Clival chordomas may secondarily extend to involve the nasopharynx and nasal cavity; however, primary extra-osseous chordomas are even more uncommon. We present an unusual case of a primary sinonasal chondroid chordoma arising from the maxillary sinus in a 5-year-old child. This is the second case of primary sinonasal chordoma reported in the literature so far, after Tao ZZ et al. and the first case of the chondroid variant. Case presentation A 5-year-old male presented with right-sided nasal obstruction, nasal congestion, and snoring for 2 months. Physical examination showed a reddish polypoidal mass in the right nasal cavity obstructing the choana with nasal septal deviation toward left side. Radiological examination with CT confirmed the presence of a well-defined, heterogeneously hyperdense lobulated mass in right maxillary sinus extending into right nasal cavity with intralesional coarse calcifications. MRI revealed expansile solid altered signal intensity mass, which appears to be isointense on T1-weighted imaging (T1WI) and heterogeneously hyperintense on T2-weighted imaging (T2WI) with a heterogeneous honeycomb pattern of enhancement. Differentials considered were rhabdomyosarcoma, naso-pharyngeal carcinoma, and neuroblastoma metastasis. However, the lesion was pathologically proven as a chondroid chordoma. No association with skull base or clival lesion was found on review. Conclusions Primary sinonasal chordomas are rare in occurrence but should be considered a differential for sinonasal masses in the presence of characteristic MRI features, despite their uncommon location.


Background
Chordoma are rare, malignant tumors arising from embryonic remnants of primitive notochord that remain entrapped in midline structures such as the clivus (at spheno-occipital synchondrosis), vertebral bodies, and sacrococcygeal region.These are low-grade, slow growing, but locally invasive tumors with a high recurrence rate and significant mortality.They are generally seen in adults; however, some histological variants are relatively common in the pediatric age group such as the dedifferentiated and chondroid variants [1].
Intracranial clival chordomas typically extend in the direction of the nasopharynx and occasionally into the nasal cavity.Primary extra-osseous chordomas have also been previously reported in the nasal cavity and nasopharynx in the absence of a clival lesion.
We present an unusual case of a primary sinonasal chondroid chordoma arising from the maxillary sinus in a 5-year-old child.This is the second case of primary sinonasal chordoma reported in the literature so far after Tao ZZ et al. [2] and the first case of the chondroid variant.

Case presentation
A 5-year-old male presented with right-sided nasal obstruction, nasal congestion, and snoring for 2 months.There was a history of facial trauma, i.e., fall over the nose one year ago.There was no history of headaches, epistaxis, or visual disturbances.
Laboratory results revealed a normal hemoglobin of 10.4 g/dl, a platelet count of 301 × 10 9 /L, and leukocyte count of 7.9 × 10 9 /L.Liver and kidney function tests were within the normal range.Coagulation studies showed no abnormality.
The patient was referred to otorhinolaryngology for further evaluation; physical examination was performed, which revealed a reddish polypoidal mass in the right nasal cavity obstructing the posterior choana with nasal septal deviation toward left side.On probe test, there was inability to delineate the lateral wall of right nasal cavity along with a mucoid nasal discharge.There was associated right maxillary and frontal tenderness.
The patient was advised computed tomography of the paranasal sinus (PNS), which confirmed the presence of a well-defined, heterogeneously hyperdense lobulated mass approximately 4 × 5 cm in the right maxillary sinus extending into the right nasal cavity and ethmoid air cells.There were few intralesional coarse calcifications, with scalloping, thinning, and rarefaction of all walls of right maxillary sinus, the medial wall of right orbit, right pterygoid base, and bony nasal septum (Fig. 1).Magnetic resonance imaging with contrast was performed, which revealed a well-defined, expansile, solid altered signal intensity mass that appears to be isointense on T1-weighted imaging (T1WI) and heterogeneously hyperintense on T2-weighted imaging (T2WI) without any diffusion restriction.It shows heterogeneous enhancement with areas of low T1 signal intensity within, giving a honeycomb appearance.Few foci of blooming were seen on SWI, which appear hypointense on PHASE sequence, suggestive of calcification (Figs. 2 and 3).
Superiorly, it is extending to involve right ethmoid air cells and reaching up to the cribriform plate.It is displacing the floor of right orbit superiorly; however, no intraorbital or intracranial extension is seen.Differentials considered were rhabdomyosarcoma, nasopharyngeal carcinoma, and neuroblastoma metastasis.
Gross primary resection of the tumor was done by a right lateral rhinotomy approach.Macroscopically, the tumor tissue was lobulated gray-white tissue that was firm to hard in consistency.
Histopathology of the mass showed lobules of chondroid matrix (predominant) with myxoid and hyaline matrix surrounded by nests, cords, and singly scattered round to polygonal cells having centrally placed hyperchromatic nuclei and moderately eosinophilic to clear cytoplasm.No mitotic activity was seen.The lobules were separated by fibrous septae.The histopathological diagnosis was chondroid chordoma (Fig. 4).
Immunohistochemistry revealed positivity for cytokeratin-8/18, S-100, and epithelial membrane antigen (EMA), consistent with chordoma.The patient was started on a radiotherapy regimen for prophylaxis, owing to the high risk of recurrence and mortality.

Discussion
Intracranial chordomas are rare, malignant tumors typically centered at the clivus, with peak prevalence in the fourth decade.They show classical imaging findings, such as being centrally located, well circumscribed, and having an expansile soft tissue mass with lytic destruction of the clivus.Symptoms depend upon structures involved at the skull base, suprasellar, and retroclival extension causing compression over the brainstem, or direct extension into the nasopharynx and nasal cavity [3].Occurrence at atypical locations such as the nasopharynx, nasal cavity, and paranasal sinus (sphenoid, ethmoid) has been previously documented.
Chordoma can be histologically classified into three variants: [1,4].Chordoma and chondrosarcomas have similar imaging appearances; they are both hypointense on T1 WI, heterogeneously hyperintense on T2 WI and show post-contrast enhancement.They can be distinguished based on the relative lateral occurrence of chondrosarcomas at the petro-occipital fissure as compared to chordomas, which are central.
Since our case lacks distinctive features based on age prevalence or lesion location, the utilization of DWI and ADC values becomes helpful to distinguish between the two lesions.
Yeom KW et al. used diffusion-weighted imaging (DWI) to distinguish chordoma and chondrosarcomas by assessing differences in cellular densities and nuclearto-cytoplasmic ratio based on the motion of water molecules within a tissue voxel.Chondrosarcomas showed higher mean ADC values compared to chordomas.However, ADC may fail as an absolute predictor of diagnosis in cases of histopathological crossover due to variants [5].Well-circumscribed lobulated mass with peripheral T2 hypointense capsule, heterogeneous contrast enhancement [11] 6 Aneurysmal bone cyst (ABC) Osteolytic lesion can be primary de novo or secondary to benign tumors such as fibrous dysplasia, central giant cell granuloma, and osteoblastoma Radiolucent expansile multiloculated masses with a soap bubble appearance.MR imaging: internal thin septae, fluid-fluid levels with septal enhancement [5] 7 Juvenile ossifying fibromas 5-10 years, more aggressive and greater chances of recurrence than their adult counterparts (3-4th decade) Well-marginated hypodense mass with sclerotic rim and internal lucent areas with mineralized foci.Low to intermediate on T1, heterogeneously hyperintense on T2, with mineralized areas appearing T2 hypointense [5] Sharp margins help differentiate from malignant lesions 8 Sinonasal organized hematoma

History of trauma present
Expansile soft tissue mass, smooth sinus wall erosion, heterogeneous signal intensity with a hypointense peripheral rim on T2-WI images, and marked irregular nodular, papillary, or frond-like enhancement due to neovascularization [12] Malignant neoplasms 9 Rhabdomyosarcoma Bimodal distribution: 2-4 years and 12-16 years of age Invasive soft tissue mass lesion, iso to hypointense T2, shows restricted diffusion with variable contrast enhancement and central areas of necrosis [13] Two histologic variants-embryonal and alveolar (poor prognosis) Associations-Li Fraumeni syndrome, neurofibromatosis type 1 10 T-cell lymphoma Epstein-Barr virus, south-east Asia, male predominance.Aggressive lesion with a poor survival rate Isointense on T1, intermediate on T2, with restricted diffusion and marked contrast enhancement [5] Other sites: Waldeyer ring, tonsils, nasopharynx Associated with cervical lymphadenopathy ADC measurements were obtained to differentiate between chordoma and chondrosarcoma by drawing a region of interest (ROI) manually, excluding areas of calcification, necrosis, and cystic change.Mean, minimum, and maximum ADC values (10 − 6 mm 2 /s) obtained, i.e., 1512, 1277, and 1801, respectively, were compared with reference values by Yeom KW et al. for chordoma (1474 ± 117, 905 ± 118 and 2199 ± 255) and chondrosarcoma (2051 ± 262, 1488 ± 360 and 2503 ± 512).The values obtained correspond with the ADC characteristics of a chordoma (Fig. 3B).
While DWI and ADC measurements offer valuable insights into tissue characteristics, their utility may be influenced by technical factors, imaging parameters, and ROI placements, necessitating further validation through additional studies [5].
Sinonasal mass lesions usually manifest with non-specific symptoms such as nasal obstruction, headache, and facial pain, making an accurate diagnosis challenging.Imaging modalities, particularly MRI, play a crucial role in characterization and surgical planning.Primary sinonasal chordomas are rare in occurrence; their key MRI features include a well-defined expansile lobulated mass with T2 hypointense septae along with honeycomb pattern of enhancement.However, it is imperative to consider a broad differential list, as outlined in Table 1, to avoid misdiagnosis [6].
Histopathological examination is the gold standard for a definitive diagnosis.Chondroid chordomas exhibit characteristic lobules of chondroid matrix with myxoid and hyaline components, distinguishable from other chordoma variants and chondrosarcomas through immunohistochemistry markers such as cytokeratin-8/18, S-100, and epithelial membrane antigen (EMA).
The optimal management of primary sinonasal chondroid chordomas involves a multidisciplinary approach comprising surgical resection and adjuvant radiotherapy.A complete en bloc surgical resection remains the cornerstone of treatment, aiming for clear margins while preserving vital structures.High-dose radiation therapy (such as proton beam) is recommended for all histological variants due to the high local recurrence [7,8].
Chondroid variants were previously believed to have a better prognosis compared to other types; however, according to Almefty K et al. [9], the biologic behavior and outcomes of chondroid chordoma are comparable with the conventional variant, emphasizing the need for vigilant surveillance and long-term follow-up.

Conclusions
Chordomas are the most common primary malignant osseous tumors of the skull base and have typical imaging features.However, in the presence of characteristic imaging features, they should be considered a differential, despite their atypical extra-osseous location.

Teaching points
1.Primary sinonasal chordomas are rare in occurrence but should be considered a differential for sinonasal masses in the presence of characteristic MRI features, despite their uncommon location.2. Imaging differentials of pediatric sinonasal mass lesions.3. Role of ADC values in the differentiation of chordomas and chondrosarcomas.

Fig. 1 A
Fig. 1 A Axial plain CT of paranasal sinus shows a well-defined, heterogeneously hyperdense mass lesion epicentered in the right maxillary sinus with extension into nasal cavity and coarse calcifications within.B, C Axial bone window shows rarefaction and expansion of all walls of right maxillary sinus, with deviation of nasal septum toward the left.D Sagittal reformatted CT in bone window shows the absence of any lytic lesion in clivus and an unfused spheno-occipital synchondrosis.E Coronal reformatted CT image shows downward bowing of the hard palate, without any osseous erosion

Fig. 2 A
Fig. 2 A T2 WI in coronal view shows a heterogeneously hyperintense lesion with T2 hypointense septae within.No intraorbital or intracranial extension was seen.B T2 WI in sagittal view shows extension into nasopharynx and close proximity to adenoids.The skull base and clivus appear unremarkable.C, D Axial T1 WI shows T1 hypointense lesion which shows a honeycomb pattern of enhancement on the post-contrast T1 sequence.No T1 hyperintense areas were seen which excludes recent intralesional hemorrhage

Fig. 3 A
Fig. 3 A, B Diffusion-weighted image at b1000 shows no areas of restricted diffusion, and ADC values were measured, which favored the signal characteristics of a chordoma.C, D Few hypointense areas are seen on phase sequence that appear hypointense on magnitude image, consistent with intralesional calcification

Fig. 4 A
Fig. 4 A, B Intraoperative image shows a right lateral rhinotomy incision with near total excision of the sinonasal mass lesion.C Gross examination shows lobulated gray-white tissue that is firm to hard in consistency.D Histopathology image shows nests and cords of round to polygonal cells with centrally placed hyperchromatic nuclei scattered in a chondroid matrix

Table 1
Imaging differentials of sinonasal mass lesions in pediatric age group