Intradural Extramedullary Tuberculoma Masquerading En Plaque Meningioma.

Extensive en plaque intradural extramedullary tuberculomas can occur as a paradoxical response to chemotherapy for intracranial tuberculomas. We report a case of 31-year-old male who presented with backache and progressive weakness and urgency of micturition. Magnetic resonance imaging dorsolumbar spine which showed an ill-defined T1 hypointense and T2 heterointense lesion noted posterior to the thoracic spinal cord, extending from C7 to D5 vertebral levels suggestive of en plaque meningioma. The patient underwent D1-D5 laminectomy, with subtotal debulking of the tumor. The histopathological examination of lesion was suggestive of granulomatous inflammation with multinucleated and Langhan type giant cells confirming the diagnosis of tuberculoma.

Introduction

Spinal intradural extramedullary tuberculoma is a rare entity. Nonosseous spinal cord tuberculomas can be in the form of extradural, intradural extramedullary or intramedullary lesions. Intramedullary tuberculomas of the spinal cord are rarely reported and intradural extramedullary tuberculomas are extremely rare.[12] Extensive en plaque intradural extramedullary tuberculomas can occur as a paradoxical response to chemotherapy for Intracranial tuberculomas.[3] This article describes an unusual case of an intradural extramedullary tuberculoma of the cervicothoracic spine mimicking an en plaque meningioma in a previously healthy HIV-negative man, without manifestation of pulmonary symptoms.

Case Report

A 31-year-old nondiabetic, nonhypertensive male presented with mid backache from 2 months with progressive weakness of both lower limbs and inability to walk from 1½ month with urgency of micturition and history of fall from steps 2 months ago. Patients’ wife had a history of pulmonary tuberculosis and took antitubercular treatment for 6 months. On clinical examination, higher mental functions and cranial nerves were normal with spastic paraplegia of both lower limbs and exaggerated reflexes with bilaterally extensor plantars. Sensory examination revealed a decrease in pain and touch from T2 dermatome. Patient's hemoglobin was 15.4 gms/dl with total leukocyte count of 9600/mm3 and differential count with a slight predominance of polymorphs 81%. Random blood sugar was 109 mg/dl. Serum creatine and blood urea were 29 and 0.7, respectively. The patient was negative for HIV, hepatitis B surface antigen, and hepatitis C virus. The patient was further evaluated by magnetic resonance imaging (MRI) dorsolumbar spine which showed an ill-defined T1 hypointense and T2 heterointense lesion noted posterior to the thoracic spinal cord, extending from C7 to D5 vertebral levels, with significant enhancement on postcontrast T1 study [Figures 1 and 2]. The lesion appears to be centered in the extramedullary compartment causing compression and anterior displacement of spinal cord with consequent syrinx formation in the cord, extending from C2 to D1 levels superiorly and D6 to D12 levels inferiorly. The enhancement of the lesion was extending inferiorly beyond D5 level, extending up to D9 vertebral level might probably represent dural tail. Although myelogram suggests intradural location of the lesion, the posterior dura was not well visualized at few levels adjacent to the lesion, associated with obliteration of epidural space. Intensely enhancing lesion posterior to the dorsal spinal cord with suspicion for dural tail suggests the possibility of en plaque meningioma. The patient underwent D1-D5 laminectomy, with subtotal debulking of the tumor. The mass was confirmed to be intradural extramedullary in location, but adherent to and compressing the medulla of the cord. Postoperatively, the patient had improved power in both lower limbs (Grade-4/5), and normal bladder function. Histopathological examination of lesion was suggestive of granulomatous inflammation with multinucleated and Langhan type giant cells confirming the diagnosis of tuberculoma [Figure 3]. The patient is then discharged with antituberculous treatment advised for 18 months.

Figure 1

Axial T2 (a) image showing heterogeneous hypointense signal lesion in the posterior extradural space showing intense enhancement on postcontrast T1 image (b)

Figure 2

Sagittal T2 (a) image of thoracic spine showing heterogeneous hypointense signal lesion in the posterior epidural space demonstrating intense enhancement spanning from D5 to D9 vertebral levels with syrinx from D6 to D12 vertebral levels

Figure 3

(a) Multiple granulomas with epithelioid cells and occasional Langhan giant cell (H and E, ×100) and (b) granuloma with epithelioid cells and Langhan giant cell surrounded by lymphocytes (H and E, ×400)

Discussion

Various presentations of tuberculosis include tuberculous arachnoiditis, nonosseous spinal tuberculoma, and spinal meningitis. Among these, spinal tuberculoma can be intradural, extradural, intramedullary, or extramedullary. Intradural extramedullary tuberculosis is the most rare type and is observed only in 1 out of 50,000 cases of tuberculosis.[45] Less than 5% of central nervous system tuberculomas are Intradural spinal tuberculoma and intradural extramedullary tuberculoma of the spinal cord (IETSC) is extremely rare.[36] Dastur reviewed 74 cases of spinal tuberculomas and the most common location of lesion location was extradural followed by arachnoidal, intramedullary, and intradural extramedullary[7] and the most common site of IETSC is thoracic spine.[18910111213]

Pathology

The pathogenesis is unclear and most of the reported cases of IETSC showed a paradoxical response during chemotherapy, ranged from 3 weeks to 1 year[381314] The exact mechanism for the paradoxical response is uncertain, however, it is being proposed that this paradoxical response is due to an interaction between the host immune reaction to the mycobacterial products and as the chemotherapy alters the host immunosuppression a paradoxical immune response occurs due to hypersensitivity to the protein derivatives of mycobacteria[31314] This paradoxical response leads to an inflammation in the arachnoid membrane, resulting in the development of tuberculoma. Some cases of en plaque intradural extramedullary tuberculomas were reported.[31516]

A patient with en plaque meningioma can present with thoracic spinal cord and nerve root compression which usually follows an episode of meningitis, while the patient was receiving antitubercular chemotherapy.[315] MRI of spine is the investigation of choice and it will demonstrate the lesion as intradural extramedullary long segmental mass mimicking en plaque meningioma.[31517] However, the differentiation between tuberculous pachymeningitis and meningioma in the form of plaques as seen in MRI is very difficult without obtaining a histopathological diagnosis.[111819] In patients with IETSC with neurological deficit, surgical treatment and antitubercular chemotherapy give good results with excellent prognosis.[10121920] Prompt surgical decompression will result in motor power and bladder function improvement.[31521]

Conclusion

Like in our case, en plaque intradural extramedullary tuberculomas are rare lesions, and only few cases are reported in the literature. Intradural extramedullary tuberculomas should be considered in the differential diagnosis of en plaque meningioma as a rare entity.

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Conflicts of interest

There are no conflicts of interest.