Primary chondrosarcoma arising from the L5 transverse process: A rare cause of chronic low back pain

Abstract

Background:

Chronic low back pain is a highly prevalent condition; however, primary spinal malignancies, though rare, carry critical clinical implications. Chondrosarcoma is a slow-growing malignant bone tumor, with spinal involvement accounting for <10% of cases. Tumors originating from the posterior vertebral elements, particularly the transverse process, are exceedingly uncommon and frequently result in delayed diagnosis due to their indolent clinical course.

Case Description:

We present a 51-year-old male with a 5-year history of intermittent low back pain who developed a progressively noticeable lumbar mass. Advanced imaging demonstrated a heterogeneous, partially calcified lesion arising from the left L5 transverse process with extension into the adjacent paraspinal soft tissues. Histopathological evaluation confirmed a Grade 1 chondrosarcoma. The patient underwent en bloc resection of the tumor, including the involved transverse process, through a posterior approach under intraoperative neuromonitoring. Postoperative imaging showed no radiological evidence of residual tumor; no adjuvant therapy was administered. At the 1-year follow-up, the patient remained asymptomatic with no radiological evidence of recurrence.

Conclusion:

Primary chondrosarcoma of the lumbar transverse process represents an exceptionally rare entity that should be considered in patients presenting with long-standing back pain accompanied by a palpable or fixed paraspinal mass or other suspicious imaging findings. Complete en bloc surgical resection remains the cornerstone of treatment and was associated with a favorable early outcome in this case, though long-term surveillance is essential, given the potential for late recurrence.

INTRODUCTION

Chronic back pain stands out as a significant global health issue due to its high prevalence and its individual and socioeconomic impacts.[12] Although the incidence of spinal malignancies among patients presenting with low back pain at primary care settings is extremely low (0.0–0.7%), it is crucial for clinicians to carefully evaluate “red flag” findings to ensure the early recognition of underlying pathologies.[4]

Chondrosarcoma is a slow-growing malignant bone tumor that originates from chondrocytes and produces hyaline cartilage matrix.[5] It accounts for approximately 10% of all primary bone tumors and is considered the third most common primary malignant bone neoplasm after myeloma and osteosarcoma.[9] It has been reported that the disease typically peaks between the fifth and seventh decades of life and is more common in the population over 50 years of age.[6] The incidence in men has been noted to be slightly higher than in women.

Anatomically, chondrosarcomas predominantly cluster in specific regions of the appendicular and axial skeletons; the vast majority of cases are located in the pelvis, scapula, proximal femur, and humerus.[10] In contrast, primary spinal chondrosarcomas are a relatively rare entity described in the literature and account for <10% of all chondrosarcoma cases. When the spine is involved, the most commonly affected segment is the thoracic region (60%), while lesions in the lumbar spine and sacrum present as a much rarer clinical picture.[6] The incidence of chondrosarcomas originating from the posterior elements of the vertebrae has not been clearly defined in the literature, and lesions arising from the spinous processes are reported extremely rare.[1,8]

This study presents a case of chondrosarcoma originating from the transverse process of the L5 vertebra, a rare site of occurrence; it discusses the diagnostic process, radiological findings, and surgical management strategies and emphasizes that this case, treated with en bloc surgical excision, contributes to the literature in terms of its rare location and underlying pathological basis.

CASE PRESENTATION

A 51-year-old male patient presented with intermittent lower back pain that had persisted for approximately 5 years and a recently noticed palpable mass in the lumbar region. Because the pain was intermittent and did not substantially interfere with the patient’s daily activities, he had not previously sought medical attention; he presented only when the pain began to interfere with his daily functioning and a palpable mass became apparent. On physical examination, a firm, fixed mass was palpated in the left lumbar paraspinal region; no tenderness was noted on palpation. Preoperative neurological examination was unremarkable, with no motor or sensory deficits and normal deep tendon reflexes.

A mass lesion with undulating contours and containing calcifications, thought to originate from the posterior elements, was observed on the lumbar plain radiograph [Figure 1a and b].

Figure 1:

Lumbar radiographs demonstrating a calcified mass with irregular and undulating contours originating from the posterior elements in the left paraspinal region: (arrow indicates the tumor mass) (a) Anteroposterior view; and (b) lateral view.

Computed tomography (CT) revealed a heterogeneous lesion measuring 5 × 4 × 6 cm, containing calcified septa possibly belonging to chondroid and osteoid matrix, extending into the paraspinal muscle groups [Figure 2a-c]. Magnetic resonance imaging (MRI) provided significant contributions to surgical planning by detailing the soft-tissue component of the lesion and its relationship with surrounding anatomical structures; a heterogeneous lesion with mixed signal intensity was observed on T2-weighted sequences [Figure 2d-f].

Figure 2:

Preoperative imaging of the lesion (arrows indicate the tumor mass in all panels). Computed tomography (CT) images demonstrate a heterogeneous mass with calcified septa suggestive of chondroid and osteoid matrix: (a) Axial CT, (b) sagittal CT, and (c) coronal CT views. Magnetic resonance imaging reveals the lesion’s soft-tissue extent and its relationship with adjacent structures: (d) Axial T2-weighted image showing heterogeneous signal intensity, (e) contrast-enhanced axial T1-weighted image demonstrating the lesion’s relationship with the transverse process, and (f) contrast-enhanced axial T1-weighted image confirming paraspinal extension.

These radiological findings were consistent with chondrosarcoma. Preoperative staging with contrast-enhanced CT of the thorax and abdomen, supplemented by whole-body positron emission tomography-CT, revealed no evidence of regional lymph node or distant metastatic disease.

An incisional biopsy was planned for diagnostic purposes, and during the procedure, the lesion was observed to have a densely calcified and firm consistency. Histopathological examination revealed atypical chondrocytes embedded within a chondroid matrix and located within lacunae, along with mild-to-moderate nuclear pleomorphism and hyperchromasia; consequently, a diagnosis of low-grade chondrosarcoma was made.

The patient underwent surgery in the second session for radical surgical excision. Under fluoroscopic guidance, the lesion margins were identified, and a left paramedian approach was used with the patient in the prone position. Intraoperative evaluation revealed that the tumor had a thick capsule, a densely calcified structure, and originated from the left L5 transverse process. No macroscopic invasion of the surrounding soft tissues was observed. As part of the surgical treatment, the tumor was resected en bloc along with the left L5 transverse process from which it originated [Figure 3].

Figure 3:

Intraoperative findings demonstrating en bloc resection of the tumor originating from the left L5 transverse process: (a) Paramedian incision planned under fluoroscopic guidance according to lesion margins; (b) surgical exposure following soft-tissue dissection with visualization of the tumor mass; and (c) gross appearance of the resected tumor specimen.

Because the resection was limited to the left L5 transverse process and did not involve the pedicle, lamina, pars interarticularis, or facet joints, spinal stability was not considered compromised, and instrumented fusion was therefore not performed. This assessment was supported by preoperative and postoperative flexion-extension radiographs, which showed no radiological evidence of segmental instability.

Intraoperative neuromonitoring was used throughout the procedure, and no postoperative neurological deficit was observed. Estimated intraoperative blood loss was approximately 150 mL, and no perioperative complications occurred. The surgical drain was removed on postoperative day 2, and the patient was discharged on postoperative day 4. Postoperative neurological examination remained normal, with no new motor or sensory deficits. Postoperative MRI and CT scans showed no evidence of residual tumor [Figure 4].

Figure 4:

Postoperative imaging demonstrating complete resection of the lesion with no evidence of residual tumor (circles indicate the surgical resection site). Computed tomography (CT) images show the surgical defect at the level of the left L5 transverse process: (a) Axial CT, (b) sagittal CT, and (c) coronal CT views. Magnetic resonance imaging further confirms the absence of residual tumor and delineates postoperative changes: (d) Axial T2-weighted image, (e) contrast-enhanced axial T1-weighted image demonstrating excision at the transverse process level, and (f) contrast-enhanced axial T1-weighted image showing postoperative soft-tissue changes.

The final histopathological evaluation of the resected specimen reported Grade 1 chondrosarcoma [Figure 5]. The case was reviewed by a multidisciplinary orthopedic oncology board, and adjuvant therapy was not recommended. However, given the potential for local recurrence in chondrosarcomas despite their low grade, regular clinical and radiological follow-up was recommended for the patient.

Figure 5:

Histopathological findings consistent with low-grade chondrosarcoma. Sections show increased cellularity within a chondroid matrix, with atypical chondrocytes located in lacunae, exhibiting binucleation, mild-to-moderate nuclear atypia, and hyperchromasia. Representative hematoxylin and eosin–stained images at different magnifications: (a) ×10, (b) ×25, (c) ×50, and (d) ×100.

During the early 1-year follow-up period, the patient’s symptoms completely resolved, and no recurrence of pain or swelling was detected during follow-up examinations. Physical examination revealed no pathological findings at the surgical site, and magnetic resonance imaging confirmed the absence of recurrence [Figure 6].

Figure 6:

Follow-up magnetic resonance imaging at one year demonstrating no evidence of local recurrence (circles indicate the resection site, without evidence of recurrence). (a) Axial T2-weighted image and (b) contrast-enhanced axial T1-weighted image showing postoperative changes without residual or recurrent tumor.

DISCUSSION

Chondrosarcomas are generally slow-growing tumors with an indolent course. Clinically, the most common presenting symptom is long-standing localized pain, and it is not uncommon for symptoms to persist for months or even years.[7] In our case, the approximately 5-year duration of symptoms is consistent with the typical clinical course of low-grade chondrosarcomas. This situation makes it difficult to diagnose spinal chondrosarcomas in the early stages and can lead to diagnostic delays.

Radiological evaluation plays a decisive role in the diagnosis of spinal chondrosarcomas and in surgical planning. While CT offers superior visualization of calcification patterns specific to the chondroid matrix, MRI allows for a detailed assessment of the tumor’s soft-tissue components and its relationship with the spinal canal and neurovascular structures. Chondrosarcomas are typically characterized by heterogeneous signal characteristics, a lobulated contour, and paraspinal extension. The mixed signal intensity and calcified septa identified in our case are consistent with the typical imaging features of this tumor group and played a significant role in establishing the preoperative diagnosis and determining the surgical approach.

Histopathological examination is essential for a definitive diagnosis, and tumor grading is the most important prognostic factor. Chondrosarcomas are graded histologically based on cellularity, nuclear size, and nuclear staining (hyperchromasia).[2] Although low-grade tumors generally have a better prognosis, the potential for local recurrence is not completely eliminated. In addition, the literature reports that molecular markers such as p53 and Ki-67 are associated with more aggressive biological behavior, particularly in high-grade tumors.[3]

Because chondrosarcomas are resistant to chemotherapy and conventional radiotherapy, surgical resection forms the cornerstone of treatment.[11] En bloc resection performed with wide surgical margins is considered the gold standard in terms of local control and long-term survival. However, due to spinal anatomical limitations, tumor location, and the need to preserve neurological structures, this approach may not always be feasible. In the present case, margin status was assessed radiologically rather than through dedicated histopathological margin analysis, which represents a limitation of this report.

In our case, the tumor was determined to originate from the left L5 transverse process, and en bloc resection was successfully performed following appropriate surgical planning. Intraoperative neuromonitoring was used during surgery, and no postoperative neurological deficit was observed. Postoperative imaging showed no evidence of residual tumor, and the patient did not develop any neurological deficits in the early postoperative period.

To the best of our knowledge, chondrosarcoma arising from the L5 transverse process represents an exceptionally rare anatomical presentation, further highlighting the need to consider atypical tumor origins in the differential diagnosis of paraspinal masses.

One of the most important prognostic factors in chondrosarcomas is the adequacy of surgical margins. Inadequate resection increases the risk of local recurrence and distant metastasis. Therefore, determining the surgical strategy through a multidisciplinary approach is of great importance, particularly in tumors with spinal involvement. Since recurrence or metastasis can develop even in low-grade tumors in the long term, long-term clinical and radiological follow-up is recommended.[8]

In our case, no signs of recurrence or metastasis were observed during this early 1-year follow-up period, and the patient’s clinical symptoms showed significant improvement. This should be regarded as a short-term result rather than evidence of a favorable long-term outcome; given the well-documented potential for late recurrence in chondrosarcomas, regular long-term clinical and radiological follow-up should be continued.

CONCLUSION

Spinal chondrosarcomas originating from the posterior elements are clinically challenging tumors that can lead to diagnostic delays due to their rarity and indolent clinical course. It is critical for early diagnosis that the possibility of malignancy not be overlooked in patients with chronic low back pain accompanied by additional concerning findings, such as a palpable or fixed paraspinal mass or suspicious imaging findings and that advanced imaging modalities be utilized in a timely manner in such cases. In surgically suitable cases, en bloc resection is the primary treatment approach that provides effective local control; however, due to anatomical limitations, the surgical strategy must be individualized. Long-term follow-up is mandatory because the risk of recurrence persists even in low-grade tumors, and the favorable course observed at this early 1-year follow-up should not be interpreted as a definitive long-term outcome.

Ethical approval:

The Institutional Review Board approval is not required.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their images and other clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of Artificial Intelligence (AI)-Assisted Technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

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