Pelvic/Sacral Chondrosarcoma with Brain Metastasis: A Case Report

Chondrosarcoma, a malignant tumor composed of hyaline cartilage, ranks as the second most prevalent primary bone tumor after osteosarcoma, with an incidence of 3 case-years per million population [1, 2]. Histologically, chondrosarcomas span a spectrum from grade I (benign) to grade III (malignant) [3]. Grade III lesions are associated with a poor prognosis, exhibiting the highest rates of local recurrence, lung metastasis, and low survival rates [4]. Distant metastases are found in 10% of grade II and 71% of grade III cases, spreading mainly to the lungs and bones such as the femur and humerus; they result in a 5-year survival rate of 18% [3]. Metastasis other than to the lungs and bones is rare, and extension to the central nervous system is even rarer (0.3%–2.3%) [5]. Herein, we aim to provide insight into the presentation, prognosis, and associated diagnostic challenges of brain metastasis in a 32-year-old woman with grade III pelvic/sacral chondrosarcoma who experienced local recurrence following surgery and radiotherapy. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary (for all online suppl. material, see https://doi.org/10.1159/000541620).

A 32-year-old woman with a history of grade III pelvic/sacral chondrosarcoma (L4-S2; T3N0MX; Ki67; 30%) underwent complete surgical resection and later fractionated radiotherapy on the lumbar/pelvic/sacral tumor bed, receiving 4,000 Gray (Gy) in 16 fractions.

Eight months later, she presented to the emergency room with a 2-day history of thunderclap headache of severe intensity, associated with fever and chills. During the diagnostic assessment, computed axial tomography (CT) scan of the brain revealed a left occipital intraparenchymal lesion with peripheral bleeding and surrounding edema, resulting in mass effect. The lesion caused collapse of the posterior horn of the lateral ventricle and midline shift from left to right measuring 7.3 mm (shown in Fig. 1).

Subsequent physical examination identified a mass in the right hip, and further evaluation through simple and contrast-enhanced magnetic resonance imaging (MRI) of the pelvis and lumbar spine revealed local recurrence of the chondrosarcoma, characterized by extensive involvement. This included invasion of the spinal canal in the lumbo-sacral region, infiltration of the left sciatic nerve, and involvement of the musculature in the gluteal region and left piriformis muscle (shown in Fig. 2).

Based on the CT scan of the brain and MRI findings of the pelvic and lumbar region, secondary brain metastasis resulting from chondrosarcoma was suspected. To further clarify the diagnosis, additional imaging modalities including simple and contrast-enhanced MRI with spectroscopy and diffusion-weighted imaging were employed.

The MRI of the brain revealed an intra-axial expansive lesion located in the left parieto-occipital region, with imaging features consistent with a metastatic lesion in accordance with the patient’s medical history: hyperintense areas in T1- and T2-weighted sequences suggestive of bleeding and marked mass effect with associated vasogenic perilesional edema, effacement of the pericerebral sulci, partial collapse of the left lateral ventricle, and midline shift (shown in Fig. 3). Spectroscopic sequences revealed an increase in lipids and lactates, along with a decrease in N-acetyl-aspartate, corresponding to the hyperintense regions observed in the diffusion sequences, indicative of necrosis.

Ten days after admission, the patient experienced a generalized tonic-clonic seizure lasting approximately 2 min, followed by postictal stupor, tachycardia, hypertension, and anisocoria (predominantly affecting the left pupil). Suspecting tumor bleeding or progression leading to brain herniation, a follow-up CT scan was performed. The scan revealed the left parieto-occipital metastatic lesion with evidence of uncal and foraminal herniation (shown in Fig. 4). This caused compression of the cardiorespiratory center at the bulbar level and caused the patient’s death.

Brain metastases are the most common type of intracranial neoplasm, accounting for 90% of all cases. It is estimated that approximately 25% of cancer patients will develop brain metastases [6]. Although any tumor can potentially metastasize to the brain, lung cancer is the most frequent primary tumor, accounting for 39%–56% of cases, followed by breast cancer (13%–19%), melanoma (6%–11%), gastrointestinal tract tumors (6%–9%), renal tumors (2%–6%), and other/unknown origins (4%–12%) [7]. However, brain metastasis from chondrosarcoma as a primary tumor is a rare event, with only a few cases documented in the literature. There are only 12 documented cases of brain metastases derived from chondrosarcoma [8], and among these, only one case involves a female under the age of 35 [9]. This report suggests that, even in cancers where brain metastasis is exceedingly rare, clinicians should not dismiss the possibility, especially when neurological symptoms emerge.

Brain metastases are frequently observed in males and typically manifest during the sixth decade of life. Most cases present with multiple metastases rather than solitary lesions, with supratentorial involvement being more prevalent than infratentorial. Notably, the parietal lobe stands out as the most frequently affected site [6]. However, our patient diverges from these statistics; she was a 32-year-old female with a solitary lesion affecting both the parietal and occipital lobes. Despite statistical trends, there are limited data on the metastatic brain behavior of grade III chondrosarcoma in younger patients. Therefore, clinicians should be aware of the potential for atypical presentations of brain metastasis in young, female patients with solitary lesions and a history of grade III chondrosarcoma.

In patients with a history of neoplasia, the sudden onset of headaches may indicate a potential brain metastasis, requiring neuroimaging for further evaluation [10]. Non-enhanced CT is the first-line imaging modality for patients with new neurological deficits due to its accessibility, patient tolerance, and rapid ability to exclude life-threatening emergencies such as hemorrhage, hydrocephalus, or significant mass effect [11]. Subsequent evaluation with contrast-enhanced CT or MRI may be indicated.

Standard MRI exhibits high sensitivity but low specificity when differentiating between brain tumors and treatment-related changes [12]. Contrast enhancement in T1-weighted images indicates a disrupted blood-brain barrier, while hyperintensity in T2 signals reflects a combination of infiltrating tumor cells, necrotic regions, and tumor edema [13]. The MRI findings in our patient align with these characteristic features.

Advanced MRI techniques such as magnetic resonance spectroscopy and diffusion-weighted imaging play a crucial role in distinguishing brain metastases from other conditions [14]. MRS allows noninvasive assessment of tissue metabolites, differentiating between neoplastic and nonneoplastic brain masses. It uses single voxel or multivoxel chemical shift imaging as its primary techniques, evaluating metabolites such as choline (indicative of cell membrane turnover), N-acetyl aspartate (a marker of neuronal integrity), lactate (a marker of anaerobic metabolism), and lipids (a by-product of necrosis). Creatine serves as an internal control for comparison with other metabolite peaks [13, 14]. The elevation of lactate in neoplasms is attributed to the anaerobic environment and altered glucose metabolism, leading to incomplete glucose breakdown. The reduction in N-acetyl aspartate signal results from decreased or absent production of this metabolite due to the destruction or displacement of normal neurons by the neoplastic process [15]. DWI often reveals restricted diffusion in intracerebral metastases, with the restriction potentially attributed to increased protein concentration, such as highly viscous mucin [16].

Imaging features play a crucial role in diagnosing brain metastasis, especially when a biopsy is not feasible. In this patient, a confirmatory biopsy was not approved due to her fragile health state; therefore, the diagnosis relied on her medical history combined with classical radiological findings characteristic of brain metastasis. Early and accurate imaging allows for the prompt identification and assessment of potential metastases, and integrating imaging results with a detailed medical history enhances diagnostic precision. Highlighting these practices can significantly improve diagnostic accuracy and optimize patient management in cases where a confirmatory biopsy is not possible.

Comprehensive diagnostic strategies aid in the identification of rare complications and improve overall patient management. These approaches ensure that even unconventional presentations are appropriately addressed. By adopting a thorough and inclusive diagnostic framework, physicians can significantly improve patient outcomes or provide a more accurate prognosis, even in the most challenging scenarios.

This report sheds light on the clinical presentation of brain metastasis derived from chondrosarcoma in younger patients (aged <35 years). It also contributes to understanding the specific sites of brain metastasis in these cases. We underscore the critical role of early and advanced imaging in diagnosing such rare complications and emphasize the importance of incorporating these findings into the differential diagnosis. By integrating imaging results with clinical context, clinicians can make more informed treatment decisions and provide accurate prognostic assessments for patients with suspected brain metastases.

The authors declare that written informed consent was obtained from the patient’s husband for publication of the details of their medical case and any accompanying images since the patient herself is deceased. Ethical approval is not required for this study in accordance with local or national guidelines.

The authors have no conflicts of interest to declare.

No funding was received for this project.

Catalina Herrán-Fonseca, Jorge Luis Vargas-Rojas, and Ramón Alejandro Andreu-Atuesta collected the data and wrote the manuscript. Sergio Andrés Salgado-Rueda provided insight into the conceptualization, preparation, and writing of the manuscript (review and editing).

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.