Optic pathways tuberculoma mimicking glioma: case report

Neoplasm

Optic Pathways Tuberculoma Mimicking Glioma: Case Report Antonio Aversa do Souto, M.D.,* Ana Luiza V. Fonseca, M.D.,* Mo ˆ nica Gadelha, M.D., PhD.,† Ine ˆs Donangelo, M.D.,† Leila Chimelli, M.D., PhD.,‡ and Fla´vio S. Domingues, M.D.* *Division of Neurosurgery, †Division of Endocrinology, ‡Department of Pathology, University Hospital–Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Aversa do Souto A, Fonseca ALV, Gadelha M, Donangelo I, Chimelli L, Domingues FS. Optic pathways tuberculoma mimicking glioma: case report. Surg Neurol 2003;60:349 –53.

KEY WORDS

Tuberculosis, optic pathway glioma, magnetic resonance imaging.

BACKGROUND

Optochiasmatic tuberculomas are very rare lesions. They can occur with concomitant tuberculous meningitis, and pulmonary tuberculosis or as the only manifestation of the disease. The authors present a case of optic pathways tuberculoma with radiologic appearance simulating an optic pathways glioma. CASE DESCRIPTION

We report a case of a 20-year-old man with mental retardation due to anoxic encephalopathy who developed a sudden bilateral amaurosis. He also presented with diabetes insipidus, panhypopituitarism, right proptosis, and chemosis. Computed tomography (CT) and magnetic resonance imaging (MRI) showed an enhancing lesion in the optochiasmatic region extending to both optic nerves, with a mass in the right orbit, mimicking an optic pathways glioma. There was no other evidence of systemic involvement of the tuberculosis. The lesion was explored through a right pterional transylvian approach with opening of the optic canal and orbital roof, and a biopsy and an internal decompression were performed. Histopathological studies demonstrated a granulomatous lesion with central caseous necrosis with acid-fast bacilli. The patient improved after treatment with tuberculostatic drugs, but vision recovery could not be achieved. CONCLUSION

Visual compromise in tuberculosis is associated with hydrocephalus, optical neuritis or tuberculomas involving the optic pathways. Reviewing the literature on tuberculomas of the optochiasmatic area, we could not find any other case with such extensive involvement of the optic pathways that was radiologically suggestive of an infiltrating glioma. Histopathological studies remain crucial in the diagnosis of intrinsic expansive processes of the optochiasmatic region. © 2003 Elsevier Inc. All rights reserved.

Address reprint requests to: Dr. Antonio Aversa do Souto, Servico de Neurocirurugia, s/n HUCFF-UFRJ 10 andar, Av. Brigadeiro Trompowski Illha do Fundao, Rio de Janeiro, Brazil. Received July 10, 2002; accepted January 15, 2003. © 2003 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710

ntracranial tuberculoma is responsible for 0.15 to 4% of the intracranial masses [14], occurring namely in the supratentorial compartment. Brain tuberculoma can develop or enlarge in patients treated for tuberculosis during anti-tuberculous chemotherapy, but can also be the first manifestation of infection with Koch’s bacilli. Despite adequate anti-tuberculous treatment, intracranial tuberculoma can still give rise to raised intracranial pressure or compression of eloquent structures such as optic pathways. Visual compromise in tuberculosis can occur because of arachnoiditis, hydrocephalus, or involvement of the anterior optic pathways by tuberculoma. Radiologically tuberculomas cannot be reliably distinguished from intrinsic neoplasms or other inflammatory lesions. We report extensive optic pathways involvement of tuberculosis as the single manifestation of the disease.

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Case Report A 20-year-old man with past medical history of developmental impairment and mental retardation secondary to perinatal hypoxia presented with a 2-month history of epilepsy, vomiting, polyuria, polydipsia, and drowsiness. His mother reported a sudden bilateral compromise of the vision one month before admission. A 2 year past family history of pulmonary tuberculosis was noted in a brother. On admission, the patient was drowsy and confused, with a mental status worse then his previous mental condition. He was dehydrated and hypotense with normal body temperature. Neuro0090-3019/03/$–see front matter doi:10.1016/S0090-3019(03)00133-2

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logic examination showed a bilateral amaurosis with deafferented pupils and a mild proptosis on the right side. The extrinsic ocular movements were preserved. Nuchal rigidity or motor deficits were absent. Laboratory findings revealed panhypopituitarism: a luteinizing hormone level of 0.7 (normal, 0.8-7.6 mIU/mL), a follicle-stimulating hormone level of 0.16 mIU/mL (normal, 0.7-11.1 mIU/ mL), a thyroid-stimulating hormone level of 0.093 ␮IU/mL (normal, 0.4-4 ␮IU/mL), a thyroxine level of 3.4 ␮g/100 mL (normal, 4.5-12.5 ␮g/100 mL), a free thyroxine level of 0.44 ng/dL (normal, 0.8-1.9 mg/ dL), a 3,5,3'-triiodothyronine level of 177 ng/dL (normal, 51-165 ng/dL), a morning cortisol level ⬍1.0 ␮g/dL (normal, 5-25 ␮g/dL), and a growth hormone level of 0.05 ng/ml (normal, 0.06-5.0 ng/mL). Prolactin level was 3.4 ng/mL (normal, 2.5-7.0 ng/mL), and the urinary density was decreased (1000). Chest X-ray was normal. A CT scan showed a mass in the optochiasmatic region heterogeneous and isodense, with enhancement after administration of the venous contrast (Figure 1). The lesion extended to the right optic nerve inside the orbit. His clinical condition and the level of consciousness improved after medical treatment with hydration and hormonal replacement therapy. The visual deficit remained unchanged and he developed chemosis and a progressive proptosis on the right side. A subsequent MRI scan revealed the whole extension of the mass in the chiasm with extension to both optic nerves inside the orbit, mainly in the right side with proptosis. After venous infusion of gadolineum, MRI scans showed an heterogeneous enhancement of the lesion (Figure 1). The clinical picture and radiologic findings were considered compatible with an aggressive optic pathways glioma. The patient was then submitted to microsurgical exploration with a right side pterional-transylvian approach. During microsurgical exploration an enlargement of both optic nerves and an intrinsic chiasm and hypothalamic mass were noted (Figure 2). After removing the right orbital roof and opening the optic canal, we confirmed the pronounced extension of the mass along the right optic nerve with transgression of the dural leaf inside the orbit. The lesion was whitish-yellow and firm without a distinct margin from the surrounding neural tissue. Biopsies from the mass inside the orbit and from the optochiasmatic region were performed, as well as a mild internal decompression. Histopathological studies showed a granulomatous tissue with caseous central necrosis. A Ziehl-Nielsen preparation identified acid-fast bacilli, confirming the tuberculous nature of the granuloma. A combined drug therapy was started with ri-

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fampin, isoniazid, and ethambutol maintained 12 months. Hormone replacement therapy with 5 mg of prednisone and 150 ␮g of levothyroxine daily has been continued with a very good clinical response. The mental status returned to its previous condition, but the complete visual deficit remained unchanged in 15 months of follow-up.

Discussion Tuberculosis remains an endemic problem in many countries. Even in developed countries the incidence of tuberculosis and its extrapulmonary manifestations has increased in the last 15 years associated with HIV infection. About 30% of patients with tuberculosis are HIV seropositive. Conversely, 5% to 9% of all AIDS patients have tuberculosis. Central nervous system (CNS) involvement is found in 10% of the patients with AIDS-related tuberculosis, but in only 2 to 5% of those with non-AIDSrelated tuberculosis [19]. Tuberculoma is an uncommon manifestation of CNS tuberculosis. The lack of previous history of tuberculosis and absence of pulmonary disease are common in new diagnosed cases of cerebral tuberculomas, as in our patient [6]. A positive tuberculine skin test is usually present, but this is a common and nonspecific finding in individuals living in endemic environments. Tuberculomas can be solitary or multiple. Most of them are situated in the supratentorial compartment but cerebellar lesions are not so rare, especially in children [4]. Radiologic findings in tuberculomas are nonspecific and frequently indistinct from other inflammatory lesions, mainly toxoplasmosis, or tumors as gliomas or lymphomas. In the CT scans, tuberculomas may show a nodular or ring enhancement [13]. The MR appearance of the tuberculomas is also quite variable [19]. Frequent associated findings are cisternal enhancement, hydrocephalus, and basal ganglia infarcts. A large lesion with important perilesional edema and a bright central core in T2-weighted sequences suggests the formation of a tuberculous abscess [19]. Histopathologically, tuberculomas are granulomas with a central zone of solid caseation necrosis surrounded by a colagenous capsule with mononuclear inflammatory cells infiltrate. The finding of acid-fast bacilli confirms the diagnosis. Nowadays, in cases in which direct examination does not reveal the bacilli, confirmatory test with polimerase chain reaction can be obtained earlier than the 6 to 8 weeks required for the definitive culture result. Anterior optic pathways can be affected by arach-

Optic Pathway Tuberculoma

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A, CT scan showing a suprasellar lesion with homogeneous contrast enhancement. B, axial Tl-weighted scan revealing a fusiforme enlargement of both optic nerves iside the orbit, mainly on the right side, with a light proptosis. C, axial Tl-weighted scan depicting a diffuse enlargement of the optic chiasm, both optic nerves and optic tract on the right side. D, axial Tl-weighted scan after gadolinium infusion showing an intense and heterogeneous enhancement of the optic chiasm and both optic nerves. E, sagittal Tl-weighted scan showing the contrast enhancing lesion at the optochiasmatic region. F, coronal Tl-weighted scan after gadolinium infusion displaying the intense enhancement of both optic nerves.

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noiditis, tuberculoma of the chiasm, and “cold” epidural abscess of the sphenoidal jugum [9]. Although involvement of the optic nerves and chiasm by meningeal tuberculous exsudate is not uncom-

mon during the course of tuberculous meningitis, visual symptoms are rare [11]. Sellar and infundibular tuberculomas are also rare and, in addition to neuroendocrinological disturbances, they can

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case. Proptosis and chemosis can be found in the clinical picture of aggressive optic pathways gliomas with intraorbital masses. Visual compromise in optic pathways gliomas is usually slowly progressive, but can be unnoticed in young children or in individuals with concomitant mental disturbances. However, sudden visual deficits have already been described in the evolution of CNS tuberculosis [9]. In conclusion, despite the great contribution of MRI in the diagnosis of expansive processes involving the optic pathways and hypothalamus, the definite diagnosis is still based on histopathological studies, and at least a microsurgical biopsy of the lesion must be performed. Tuberculoma can develop along the optic pathways and should be considered in the differential diagnosis of the masses at the optochiasmatic area. REFERENCES

Intraoperative view during the microsurgical exploration through a right side pterional transylvian approach, after unroofing of the optic canal. The anterior clinoid process (acp) was partially removed. A diffuse enlargement of the optic chiasm (oc) and the right optic nerve (on) can be noted. The Internal Carotid Artery (ICA) was laterally displaced.

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eventually be associated with visual deficits [1,2,14]. The MR finding of a thickened pituitary stalk has been considered useful for the diagnosis of pituitary tuberculomas [1,14,18]. Panhypopituitarism and diabetes insipidus can rarely occur in tuberculous meningitis but they have been frequently seen in sellar or hypothalamic tuberculomas [2,8,14,16]. In our case, the hypothalamic involvement by the tuberculoma was the cause of the prominent neuroendocrinological symptoms. Tuberculomas of the chiasm and optic nerves are extremely rare [9,11,12,15]. We could not find, in the literature, a similar case of tuberculoma with such an extensive involvement of both optic nerves with a large mass inside the orbit. The CT and MRI findings in our patient were considered very suggestive of an extensive optic pathways glioma. The familial past history of tuberculosis is a common finding in our country and was initially not considered determinant to the diagnosis in the reported

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he whole aim of practical politics is to keep the populace in a continual state of alarm (and hence clamorous to be led to safety) by menacing them with an endless series of hobgoblins, all of them imaginary.

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—H. L. Mencken