CASE 18724 Published on 08.10.2024

At the edge of the seat – Skull base chondrosarcoma

Section

Neuroradiology

Case Type

Clinical Case

Authors

Ajith Varrior, Sunita Kale, Priti Bolke

Patient

21 years, female

Categories
Area of Interest CNS, Neuroradiology brain ; Imaging Technique CT, MR
Clinical History

A 21-year-old girl presented with complaints of headache since five months, which progressed significantly over a few days. She also developed diplopia over the past two days.

Imaging Findings

MRI of the brain showed a well-defined extra-axial T2 hyperintense lesion epicentered in the right lateral wall of the body of the sphenoid bone (Figure 1). There were few hypointense foci within, which showed susceptibility, suggesting calcifications (Figures 2a and 2b). It was hypointense on T1-weighted sequence without diffusion restriction (Figures 3a and 3b). It was lifting the dura laterally. There was a mass effect on the right temporal lobe. The right ICA was displaced anterosuperiorly. There was an effacement of the CSF in the right Meckel’s cave. The lesion showed septonodular enhancement. On unenhanced CT, the lesion showed ring and arc calcifications with scalloping of the sphenoid body (Figures 4a and 4b).

The patient underwent surgical resection of the lesion, and the specimen was sent for histopathological analysis.

Discussion

Chondrosarcoma is a mesenchymal tumour arising from the embryonic remnants of the cartilaginous matrix. Skull-based chondrosarcoma accounts for less than 0.5% of intracranial tumours, and around 6% of the skull base tumours [1,2]. Approximately 75% of chondrosarcomas arise from the skull base (petro-occipital fissure), typically in a paramidline location, although they may arise from the dura mater, choroid plexus, or even the brain parenchyma [3,4].

They are seen in the fourth and fifth decades of life, and are slightly more common in women [5]. Symptoms are usually headaches, with signs of increased intracranial pressure. Rarely there might be features of hypopituitarism due to involvement of the sella or suprasellar region. These tumours show a locally aggressive growth [5].

Computed tomography (CT) and magnetic resonance imaging (MRI) are the preferred investigation tools for diagnosing and mapping the disease’s extent. CT is useful in depicting the ring and arc calcifications within the tumour and its relation with the adjacent bony structures. These tumours are iso-hypodense in attenuation in comparison to the normal brain parenchyma. CT angiography is helpful in delineating the relation with the intracranial vessels. On MRI, the lesion is hyperintense on T2 sequences (cartilaginous nature). There are scattered hypointense foci due to calcifications, also appreciated on susceptibility weighted sequences. They are hypointense on T1 sequences, without diffusion restriction. Chondrosarcomas show typical septonodular enhancement, which is seen with tumours of cartilaginous origin. Intracranial chondrosarcomas are often avascular on digital subtraction angiography [2].

Common differentials include clival chordoma, which is typically a midline lesion. It lacks the chondroid calcifications. Although difficult to differentiate from chondrosarcomas on conventional MRI apart from the location, they have lower ADC values on diffusion-weighted imaging [6]. A plasmacytoma also occurs commonly in the midline, but it has a low to intermediate signal on T2 [5]. Metastases are typically multiple and do not have a predilection to involve the petro-occipital fissure [5]. ADC values are lower in metastases compared to chondrosarcomas [6]. On dynamic contrast MRI enhancement, a Vp (fraction plasma volume) is the lowest for chondrosarcomas, intermediate in chordomas and highest in metastases [6]. Meningiomas have a lesser signal on T2 compared to chondrosarcomas, and they enhance avidly with a dural tail sign.

There is a high risk of recurrence, hence aggressive surgical resection is the preferred treatment [4]. The use of chemoradiotherapy is controversial, although some suggest a delay in the recurrence.

Differential Diagnosis List
Trigeminal schwannoma
Skull base chondrosarcoma
Chordoma
Meningioma
Final Diagnosis
Skull base chondrosarcoma
Case information
URL: https://www.eurorad.org/case/18724
DOI: 10.35100/eurorad/case.18724
ISSN: 1563-4086
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