Non‐contiguous multilevel spinal tuberculosis: A case report of unusual spinal tuberculosis resembling spinal metastasis

Abstract

Spinal tuberculosis (TB) is diagnostically challenging, particularly in atypical forms. Non‐contiguous multilevel spinal TB (NMLST) is a rare presentation of spinal TB, mimicking spinal malignancies. We reported an unusual NMLST case with a paraspinal and epidural abscess in a young patient with misleading clinical and imaging presentations.

Extra‐pulmonary TB can manifest with a variety of non‐specific presentations. The possibility of TB should always be kept in mind in endemic regions for prompt diagnosis and intervention to prevent severe sequels.

1. INTRODUCTION

Tuberculosis (TB) is a chronic granulomatous infection caused by aerosolized inhalation of Mycobacterium Tuberculosis. ¹ The World Health Organization estimates that in 2021, almost 4.1 million people will suffer from TB. ² TB is the second leading cause of death due to an infectious disease in the COVID‐19 era, claiming 1.5 million lives per year. ² , ³ Although pulmonary TB is the most common presentation, extra‐pulmonary involvement may occur, with or without pulmonary infection. Approximately 16% of TB cases are extra‐pulmonary, of which 10% have musculoskeletal involvement ² , ³ ; spinal TB (tuberculosis spondylitis or Pott's disease) accounted for nearly 1% of all TB cases. ⁴

Spinal TB usually presents insidiously due to hematogenous dissemination from the primary source. ⁵ The thoracolumbar region is more common, followed by cervical and sacral involvement. ⁵ Typically, spinal TB involves two or more contiguous vertebrae and intervertebral discs, which could be associated with paraspinal extensions, abscess formation, vertebral destruction, cord compression, and spinal deformity. ⁶ On imaging, typical findings are easily recognizable, but atypical forms may resemble other possible diagnoses and usually mandate more thorough and invasive investigations. ⁷ , ⁸

One atypical form is vertebral lesions separated by intact vertebrae (i.e., skip lesions) with spared intervertebral disc, which mislead toward other potential diagnoses, including pyogenic spondylitis and malignancy. ⁹ This non‐contiguous multilevel spinal TB (NMLST) is quite rare, with inconsistent incidence reports, ranging from 1.1% to 71.4%, highlighting the importance of whole‐spine imaging and more wide‐ranging investigations. ¹⁰ , ¹¹ Herein, we reported a quite unusual NMLST from southeast Iran with preserved intervertebral discs accompanied by large paravertebral soft‐tissue masses extending to the neural foramen, epidural space, and compressing spinal cord in a middle‐aged male patient, which led to a challenging diagnostic dilemma. Also, we reviewed the relevant literature and discussed the educational notes.

2. CASE PRESENTATION

A 37‐year‐old male patient presented with chronic, progressive back pain, paresthesia, and weakness of lower limbs in the last 2 months, which had led to abnormal gait. Moreover, he had constitutional symptoms, including low‐grade fever, loss of appetite, and a significant 10 kg weight loss in the last 2 months. He denied any history of a specific disease, including sexually transmitted diseases or malignancy, except for an infected left shoulder wound after a falling 2 years ago that had been partially managed with frequent courses of intravenous antibiotics, wound debridement, and drainage. Also, there was no clear history of TB exposure, including in his family, and unclear BCG vaccination.

At the admission, he was afebrile and hemodynamically stable but with a cachectic appearance and unable to walk without help. A crusted ulcer was noted at the left upper thorax, below the lateral half of the clavicle. A physical examination revealed a local tenderness around the paraspinal region at the upper thoracic level. Neurologic examination revealed sensory deficit below T10 as a bilateral symmetric paresthesia and proprioception sensory deficit of lower limbs. A significant symmetric paraparesis accompanied by ataxic spastic gait was also noted at the motor examination, along with increased deep tendon reflexes of the lower extremities.

Initial laboratory investigation revealed a white blood cell count of 9.2 * 1000/mm³ (upper limits of normal range) with 66% of polymorphonuclear cells and hypo‐chromic/microcytic anemia with hemoglobin of 9.7 mg/dL. The erythrocyte sedimentation rate was 83 mm/h (normal range for men under 50 years <15), and C‐reactive protein was 12 (normal range <10 mg/L). Viral markers for hepatitis and HIV were reported as negative.

On routine imaging, chest radiography showed multiple lobulated opacities at the left paraspinal region, atelectasis of the left upper lobe (LUL), and left hilar enlargement, which was neither indicative of hilum overlay sign nor suggestive of a mediastinal mass. Additionally, several opacities were evident in the left pleura's lateral margin, which, together with previous findings, raised our suspicion of malignancy (Figure 1). These findings required more radiological evaluation with computed tomography (CT) or magnetic resonance imaging (MRI), while spinal imaging was the top priority due to progressive neurological deficits.

FIGURE 1.

Chest radiograph of the patient. The left lobulated paraspinal opacities, LUL atelectasis, and multiple left pleural oval‐shaped opacities are noted (arrows). There is no evidence of cavitary lesions. LUL, left upper lobe.

An emergent spinal MRI was requested to explore the cause of cord compression. The MRI revealed large paravertebral lobulated soft‐tissue masses adjacent to the C7 and T6 vertebral bodies measuring 49 * 27 mm and 71 * 27 m, respectively, extending into the right neural foramen and posterolateral epidural space and causing a significant compressive effect on the cord as well as the abnormal high signal intensity in the adjacent cord. Furthermore, abnormal bone signals in C7, T3, and T6 vertebral bodies, posterior elements, and spinous processes were demonstrated (low‐intensity on T1‐weighted and high‐intensity on T2‐weighted) and (short‐TI inversion recovery [STIR] images). In adjacent structures, the involvement of paraspinal muscles, the left pleura with multiple oval‐shaped masses, and the sixth rib and enlarged para‐aortic lymph nodes were detected (Figures 2, 3, 4).

FIGURE 2.

Spinal MRI (sagittal view); large paravertebral lobulated soft tissue (arrows) and changes in signal intensity at the C7 level. The T1W image shows a low signal intensity (A); the T2W image (B); the STIR image shows a high signal intensity (C). STIR, short‐TI inversion recovery.

FIGURE 3.

Spinal MRI (sagittal view); the compressive effect of the lesion, large paravertebral lobulated soft tissue, and changes in signal intensity at multiple separated levels of thoracic vertebral bodies without collapse as well as uninvolved intervertebral discs. The myelogram shows CSF blockade (arrowhead) at the thoracolumbar junction level (A); the T1‐weighted image shows a low signal intensity for both involved vertebral bodies and abscess (B); the T2‐weighted image (C) and STIR image show high signal intensity in involved vertebral bodies and also paravertebral abscess (D). CSF, cerebrospinal fluid; STIR, short‐TI inversion recovery.

FIGURE 4.

Spinal MRI (axial view). Bony destruction in the right side of the posterior arc and body of the inferior thoracic vertebra is evident (arrowhead), suggesting osteomyelitis. Also, the right paraspinal abscess that extended to the right neural foramen and spinal canal caused thecal sac compression (arrow), canal stenosis, and cord compression. Evidence of left empyema can be seen (red arrows). T2‐weighted FSE image (A); the STIR image (B). FSE, fast spin‐echo; STIR, short‐TI inversion recovery.

Based on clinical, laboratory, and imaging findings, the presumptive diagnosis was primary spinal malignancy or metastasis, requiring a malignant disease workup. The other possible diagnosis was pyogenic spondylitis, given the non‐healing ulcer, a collection at the left shoulder region, and evidence of paravertebral abscess. The whole‐spine MRI was required to examine whether other levels were involved. However, due to the instrumental access limitations and progressive neurologic deficits caused by cord compression, the patient was a candidate for emergent decompressive surgery after significant compression on the upper thoracic spinal cord was demonstrated. Thus, paravertebral pockets were evacuated using the posterior midline approach, laminectomy and further pus drainage through the spinal canal were performed, samples from pus, laminae bone, and soft tissue were taken, and thorough irrigation, debridement, and drain placement were done.

Lastly, biopsies from paravertebral and epidural lesions were obtained. Microscopic examination showed fibro‐connective tissue with marked infiltrative of chronic inflammatory cells accompanied by a collection of epithelioid and Langhans giant cells with caseous necrosis. Additionally, fragments of destructed bone trabecula were seen in the examination. Altogether, these findings were compatible with chronic granulomatosis inflammation with caseous necrosis, suggestive of TB (Figure 5).

FIGURE 5.

Histopathological findings of the paravertebral and epidural lesion revealed chronic granulomatous inflammation with caseous necrosis. (A) hematoxylin and eosin (H&E) ×100, and (B) H&E ×400.

Postoperatively, anti‐TB treatment, including rifampin 10 mg/kg/day, isoniazid 5 mg/kg/day, pyrazinamide 25 mg/kg/day, and ethambutol 15 mg/kg/day, was initiated consequently. After that, neurologic deficits resolved gradually, and the patient responded satisfactorily to anti‐TB treatment, reporting further neurological improvement at discharge. Although identifying susceptibility to drugs is advisable at the baseline and during treatment, we could not perform such tests due to our limitations. Afterward, the patient showed further improvement in his clinical condition in a short‐term follow‐up a few months after starting anti‐TB therapy; nevertheless, despite our effort to follow his condition, we could not reach the patient for a long‐term follow‐up (i.e., 1 year after the initial management) to reassess his clinical and radiological findings.

3. DISCUSSION

In extra‐pulmonary TB, the infection spreads through the paravertebral venous plexus and initially settles at the anterior corners of the vertebrae. ⁵ The most common sites are thoracic and lumbar regions, followed by the cervical and sacral spine, ⁶ and typically involve adjacent structures, like vertebral bodies and intervertebral discs. ⁵ Atypical cases may present with posterior elements involvement (i.e., pedicle, transverse and spinous processes, and lamina), spared vertebral body and disc, solitary vertebral bone destruction without intervertebral disc involvement, non‐contiguous skip lesions (i.e., affecting two or more separated spinal regions), and extradural lesions with preserved vertebral bone. ⁹

Non‐contiguous multilevel spinal TB is a rare, atypical form of spinal TB and may have a higher incidence than reported. ¹⁰ , ¹¹ Novel imaging approaches (e.g., routine whole‐spine MRI) increased reports of atypical presentations in recent years. The NMLST incidence ranges from 1.1% ¹² to 71.4%. ¹⁰ However, the latter study might be biased because it was conducted at a regional referral center for spinal deformity and a small number of total cases. Additionally, this incidence rate discrepancy may be caused by different imaging modalities.

Herein, we presented an NMLST case with two segregated levels of involvement of vertebral body and posterior elements, which occurred in the cervical and thoracic regions, paravertebral and epidural abscesses, and intact intervertebral discs. Mostly, NMLST cases have two non‐contiguous levels of involvement, while there are few cases with more than two sites and only eight reports with extensive whole‐spine involvement. ¹³ , ¹⁴ , ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸

The diagnosis is mainly based on imaging in conjugation with clinical suspicion, which should be established by serology and histopathology. MRI is the modality of choice due to higher sensitivity and specificity for soft tissues than other options. ¹⁹ Typically, MRI demonstrates decreased signal intensity on T1‐weighted (T1W) but higher intensity on T2‐weighted (T2W) and short‐TI inversion recovery (STIR) in the vertebrae and their adjacent discs and soft‐tissue collections. ⁷ , ¹⁹ However, differentiating spinal TB on imaging alone could be challenging in some cases, like the case presented here.

The unique aspect of our case is the combination of NMLST with posterior lesions, preserved intervertebral discs, and soft‐tissue components in paraspinal and cord compression, which resemble pyogenic spondylitis and spinal malignancy. ²⁰ Pyogenic vertebral osteomyelitis and spondylodiscitis are commonly caused by Staphylococcus aureus. ²¹ Potential risk factors are intravenous drug abuse, diabetes, recent systemic infection, immunosuppression, or malignancy, while TB as a causative agent is often seen in immunocompromised patients or endemic areas with low socioeconomic status. ²¹ Several features in MRI are suggested to differentiate spinal TB from pyogenic spondylodiscitis, including heterogeneous T1W signal, epidural abscess/phlegmon, and severe vertebral destruction in cases from a highly TB prevalent region. ²²

Paravertebral TB abscesses tend to extend beyond osseous involvement with intervertebral discs sparing, demonstrated as T1W hypointensity and T2W hyperintensity with a thin contrast‐enhancing wall on MRI; in contrast, pyogenic spondylitis usually forms abscesses with thick and irregularly enhancing walls, early herniation and disc destruction. ²³ In a review of 26 spinal TB cases, only one had non‐contiguous thoracic and lumbar involvement. ²⁴ Notably, abscesses were present in 15 patients, 12 of which had an abscess at the initial presentation, and in the other 3, abscesses developed during treatment, highlighting the importance of following patients to detect abscess. ²⁴

Although paravertebral masses are highly suggestive of spinal TB, non‐contiguous multilevel lesions with intact intervertebral discs are usually seen in malignancies, ¹⁵ , ²³ , ²⁵ which could misdiagnose spinal TB as malignancy. ²⁶ , ²⁷ Bone metastases are the most common spinal neoplastic diseases, usually involving lower thoracic and upper lumbar and spinal TB. ²⁵ Spinal metastases show T1W hypointensity and T2W and STIR hyperintensity, involving multiple non‐contiguous vertebral bodies, particularly posterior elements with preserved intervertebral discs. ²⁵ Notably, posterior element involvement in spinal TB is atypical and could predispose to neurological deficits. ⁸

To differentiate metastatic disease from spinal TB, Du et al. introduced a scoring system based on five features: history of malignancy, subligamentous spreading, posterior element lesions, sequestrate formation, and preserved disc. ²⁸ In this scoring system, spinal metastasis gets a higher score than spinal TB, with a cutoff value of 5, demonstrating 97.85% sensitivity and 88.33% specificity for metastatic disease. Intriguingly, according to this scoring system, our case gets a score of 8 in favor of metastasis. Therefore, such a scoring system may not be applicable in all conditions, particularly in patients from endemic regions for TB like our case (estimated 10–49 per 100,000 for the country ²⁹ ); TB should always be kept in mind. In our case, histopathological examination ruled out metastatic disease despite highly suggestive features.

Another alternative in our case, though less likely, was pyogenic spondylitis, considering a non‐healing soft‐tissue infection that formed an abscess in his shoulder as a significant risk factor, partially managed by several oral and intravenous antibiotic courses. However, the patient was a candidate for emergent decompressive laminectomy and abscess drainage due to progressive neurological deficits. A biopsy was performed, and pathology suggests TB infection as a highly possible diagnosis. Therefore, our case highlights the histopathological assessment in uncertain diagnosis, which may lead to treatment delay and error.

The cornerstone of spinal TB treatment is anti‐TB agents. The recommended regimen for spinal TB treatment empirically is the 4‐drug regimen, for usually 9–12 months, though the recommendation on multiple spine involvement (especially NMLST) is deficient. Further, the susceptibility pattern of M. tuberculosis to the anti‐TB agents should be (if feasible) identified to guide the treatment regimen accordingly. ³⁰ On the contrary, surgical decompression is indicated for cases with spinal cord compression, neurological deficits, vertebral destruction leading to spinal instability and deformity, and large paravertebral abscesses. ¹³ However, thorough evidence‐based guidance for treatment protocol, particularly surgical procedures for NMLST, is lacking. Since the diagnosis was not certain in our case until pathology results, the antibiotic therapy was not started until the TB infection was revealed.

4. CONCLUSION

In conclusion, we reported an uncommon manifestation of TB as an NMLST from southeast Iran, an endemic region for TB. The diagnosis of TB should always be kept in mind in endemic regions, even when its manifestations are against the usual TB presentation. Increasing awareness of atypical TB spondylitis is crucial, given the emerging prevalence of TB in both endemic and non‐endemic regions. Prompt diagnosis is vital to determine the appropriate treatment and prevent severe sequels and morbidities. Additionally, the only way to reach a definite diagnosis in most circumstances is through biopsy and histopathological examination.

AUTHOR CONTRIBUTIONS

SA was responsible for the patient's operation, involved in patient care, and reviewed the literature. PP and FT were involved in patient documents and data collection, reviewed the literature, and drafted and wrote the manuscript. MM, MN, and ZJ assisted in the literature review. SA and FT critically reviewed and edited the final version. All authors read and approved the final manuscript.

FUNDING INFORMATION

The authors did not receive any fund for this work.

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no competing interests.

ETHICAL APPROVAL

The Institutional Review Board and Ethics Committee of Zahedan University of Medical Sciences waived the requirement for ethical approval.

CONSENT

Written informed consent was obtained from the patient to publish this case report and any accompanying images.

Fard SA, Pourzand P, Tabasi F, Mohammadi M, Nafeli M, Jourahmad Z. Non‐contiguous multilevel spinal tuberculosis: A case report of unusual spinal tuberculosis resembling spinal metastasis. Clin Case Rep. 2023;11:e7053. doi: 10.1002/ccr3.7053

DATA AVAILABILITY STATEMENT

Data sharing is not applicable to this article as no datasets were generated or analysed during the current study.