Extensive Multilevel Spinal and Extraspinal Involvement in a Case of Calvarial Tuberculosis: A Rare Disseminated Presentation

Tuberculosis (TB) continues to pose a significant global health challenge, with extrapulmonary forms accounting for approximately 15–20% of all cases. Among these, skeletal TB is relatively uncommon and can present with diverse clinical manifestations depending on the site of involvement. Calvarial tuberculosis is particularly rare, comprising less than 1% of skeletal TB cases, and its dissemination to the spine or soft tissues is even more exceptional [1,2]. In this report, we present a unique case of disseminated TB initially manifesting as calvarial involvement, later progressing to include extensive vertebral, paravertebral, and pulmonary disease.

A 6-year-old child presented to the emergency department following a fall from a significant height, landing on the occipital region of the head. At the time of injury, the child was conscious and neurologically intact. A non-contrast computed tomography (CT) scan of the brain was performed, which did not reveal any acute intracranial abnormalities, skull fractures, or significant soft tissue injury. The child was managed conservatively and discharged with instructions for follow-up. Two weeks later, the patient was brought back with a gradually enlarging, non-tender swelling over the occipital region. The parents reported no fever, weight loss, or neurological symptoms, but noted that the swelling had progressively increased in size without signs of redness or warmth. On examination, the swelling was firm, fluctuant, and localized to the midline occipital region, without overlying skin changes or signs of infection. A repeat CT scan of the head, now with bone window settings, revealed a well-defined lytic lesion involving the midline occipital bone. The lesion caused cortical thinning and expansion, with a defect noted in the inner and outer tables of the skull. There was an associated soft tissue component extending extracranially, but no evidence of intracranial extension. Magnetic resonance imaging (MRI) was subsequently performed for further characterization. The lesion appeared hypointense on T1-weighted images and hyperintense on T2-weighted sequences, with no significant post-contrast enhancement. Based on the radiological features and the absence of systemic symptoms, an intradiploic epidermoid cyst was initially considered the most likely diagnosis (Figure 1a).

The patient subsequently underwent a suboccipital craniotomy for excision of the occipital lesion. Intraoperatively, a lytic bone defect was noted in the midline occipital bone, containing caseous material. The underlying dura appeared intact, and there was no communication with intracranial structures. The soft tissue mass was excised along with debridement of the affected bone.Histopathological examination of the excised tissue revealed granulomatous inflammation characterized by epithelioid cell granulomas with central caseation necrosis and Langhans-type giant cells, consistent with a diagnosis of tuberculous osteomyelitis of the calvarium. Ziehl-Neelsen staining confirmed the presence of acid-fast bacilli, establishing a definitive diagnosis of calvarial tuberculosis [10,11]. The patient was started on a standard four-drug antitubercular therapy (ATT) regimen, consisting of isoniazid, rifampicin, pyrazinamide, and ethambutol. A follow-up MRI of the brain and skull, performed one month postoperatively, demonstrated near-complete resolution of the extracranial and extradural soft tissue components, with no new lesions or recurrence at the surgical site.Despite the encouraging local response, the clinical team opted to perform a whole-spine MRI to assess for possible systemic dissemination, given the atypical presentation and potential for hematogenous spread in pediatric TB. Surprisingly, the spinal imaging revealed extensive abnormalities involving both the cervical and lumbar regions of the spine. These included: (Figure 2a and Figure 2b).

Additional findings included a large right psoas abscess and pulmonary involvement with cervical and mediastinal lymphadenopathy commonly seen in disseminated spinal TB(13). In view of the extensive spinal and paraspinal involvement noted on MRI, and considering the possibility of atypical progression despite first-line therapy, tuberculous drug resistance was suspected. Although the patient had shown partial local response at the calvarial site, the emergence of multifocal spinal lesions raised concern for multidrug- resistant tuberculosis (MDR-TB) or suboptimal drug penetration to extrapulmonary foci.

To further evaluate the microbial sensitivity profile, CT-guided aspiration of a paraspinal abscess was advised. Under sterile conditions and imaging guidance, purulent material was aspirated from one of the lumbar paraspinal collections and sent for GeneXpert MTB/RIF assay, line probe assay, mycobacterial culture, and drug susceptibility testing (DST).

The aspirated paraspinal fluid was positive for Mycobacterium tuberculosis on GeneXpert MTB/RIF assay, which also detected rifampicin resistance, suggesting a multidrug-resistant tuberculosis (MDR-TB) strain. This was later confirmed by line probe assay and conventional culture-based drug susceptibility testing (DST), which demonstrated resistance to both isoniazid and rifampicin, with sensitivity to fluoroquinolones and second-line injectable agents.

In light of these findings, the patient was diagnosed with disseminated MDR-TB, involving the calvarium, cervical and lumbar spine, and paraspinal soft tissues. Given the severity of the disease and the patient’s age, a tailored second-line antitubercular therapy regimen was initiated in accordance with World Health Organization (WHO) guidelines for pediatric MDR-TB [14]. The regimen included:
• Levofloxacin (fluoroquinolone)
• Amikacin (aminoglycoside)
• Ethionamide
• Cycloserine
• Pyrazinamide (continued as it remained sensitive)
• Linezolid, added for its CNS penetration and efficacy in complicated MDR-TB cases

The patient was also started on vitamin B6 (pyridoxine) supplementation to mitigate neurotoxicity associated with cycloserine and linezolid. Close monitoring was instituted for potential drug-related side effects, particularly ototoxicity from amikacin and hematologic suppression from linezolid.A multidisciplinary team comprising pediatric infectious disease specialists, neurologists, and neurosurgeons was involved in the ongoing management. The decision was made to continue conservative management of the spinal lesions as there were no signs of neurological impairment or spinal instability. Serial imaging was planned to monitor the therapeutic response.This case illustrates the critical role of early microbiologic confirmation in atypical TB presentations, particularly in pediatric patients with unusual or rapidly progressive disease patterns. Timely identification of drug resistance allowed for prompt modification of therapy, potentially averting severe complications such as spinal cord compression or systemic dissemination.

This case illustrates a rare and aggressive form of disseminated TB that initially presented as localized calvarial tuberculosis. Calvarial TB is a rare entity, accounting for 0.2–1.3% of skeletal TB (4,5). It commonly presents with scalp swelling and punched-out bone defects on imaging (1,2,3,6). MRI plays a crucial role in evaluating extent and complications (8).

Dissemination to multiple spinal levels and extraspinal sites such as the psoas muscle and lungs is exceedingly rare (7,9). Spinal TB usually affects contiguous vertebral segments, and extensive multi-regional involvement—as seen in this case—is atypical (8,9). The presence of a large psoas abscess, epidural extension, and lung involvement raises suspicion of drug-resistant TB or hematogenous spread from a primary pulmonary focus (7). The need for early microbiological confirmation, culture, and drug susceptibility testing is emphasized to guide targeted therapy (9). This case also highlights the importance of considering tuberculosis in differential diagnosis of unusual scalp swellings and skull lesions, especially in endemic regions (6,7).

This case highlights the critical need for a high index of suspicion and comprehensive systemic evaluation in cases of skeletal tuberculosis, especially when initial lesions are detected in uncommon sites such as the calvarium. Calvarial tuberculosis is an exceedingly rare manifestation, often misdiagnosed due to its nonspecific presentation and radiologic resemblance to other benign lesions, such as epidermoid cysts or Langerhans cell histiocytosis. Our patient’s progression from an isolated calvarial lesion to widespread vertebral, paraspinal, and pulmonary involvement illustrates the potential for hematogenous dissemination and the multifocal nature of extrapulmonary TB, particularly in pediatric populations. This underscores the importance of whole-body imaging, including spinal MRI, in the workup of skeletal TB—even when the primary lesion appears localized. Most crucially, this case demonstrates the necessity of early microbiological confirmation, including GeneXpert MTB/RIF testing and full drug susceptibility profiling, in any patient with progressive or multifocal TB, to detect drug-resistant strains. Early detection of MDR-TB allowed for timely initiation of second-line therapy, likely preventing severe complications such as spinal cord compression, neurological deficits, or deformity. Multidisciplinary collaboration and adherence to WHO guidelines for MDR-TB management are essential for optimizing outcomes in such complex cases. Clinicians should remain vigilant for atypical presentations of TB and initiate prompt, individualized therapy based on microbiologic data to reduce morbidity and improve prognosis.

a. Funding The authors did not receive support from any organization for the submitted work.
b. Conflicts of interest/Competing interests (include appropriate disclosures) The authors have no conflicts of interest to declare that are relevant to the content of this article
c. Ethics approval and consent to participate The study is approved by institutional ethics committee (IEC). Written consent has been taken from the participant parent to publish the study.
d. Availability of data and material : not applicable
e. Consent for publication All authors have reviewed and approved the final version of the manuscript
f. Authors’ contributions Dr Harsh : conceived and designed the study Dr Preeti : contributed to the data analysis and wrote the manuscript Dr Abhaya Kumar : provided critical feedback and revised the manuscript
g. Acknowledgement : We acknowledge our department of neurosurgery.

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