Tuberculoma

Tuberculomas are most commonly seen in areas where tuberculosis is endemic. In these areas, tuberculomas can account for between 30%-50% of intracranial masses.[20][3] India and parts of Asia are two areas where tuberculomas have been noted to be particularly prevalent.[21] They occur most often as solitary lesions in young children.[3]

Pulmonary tuberculomas are among the most common benign nodules, with 5%-24% of all resected nodules being of tuberculous origin.[22] In areas of lower prevalence, such as the United States, they are most frequently seen in the setting of an acquired immunodeficiency.[23]

Symptoms are based on the location of the tuberculoma. Small, scattered lesions may be asymptomatic. Intracranial tuberculomas in children are often infratentorial, occurring near the cerebellum and base of the brain. In this population, symptoms such as headache, fever, focal neurologic findings and seizures have been seen[3] in addition to papilledema with or without meningitis.[21] When the size of a brainstem tuberculoma grows to the point of narrowing the fourth ventricle, obstructing hydrocephalus and its related symptoms can arise.[21] Rupture of tuberculomas adjacent to the arachnoid can lead to arachnoiditis.[23]

The appearance of a tuberculoma on imaging can vary according to the composition and age of the mass. They may appear as either non-caseating or solidly caseating lesions.[21] Initially, tuberculomas appear hypodense on CT with significant surrounding edema.[23][3] The "target sign" is pathognomonic for tuberculoma on CT, with a nodular ring-enhancing mass and central calcification.[24][21] The characteristic ring-enhanced appearance is due to lack of blood supply in the central necrotic core that is visualized with injected contrast.[20] Sometimes a hypodense central area is seen instead of calcification.[25] When considering other potential intracranial masses in a differential diagnosis, such as cysticercosis, pyogenic abscess, and neoplastic lesions, tuberculoma can be identified by its larger size (>2 cm), edema, and irregular border.

MRI is another useful imaging modality for diagnosing and characterizing of tuberculomas, especially solid caseous necrosis in which 3 zones of varying intensity are seen.[20]

Tuberculoma is commonly treated through the HRZE drug combination (Isoniazid, Rifampin, Pyrazinamide, Ethambutol) followed by maintenance therapy.[26] Per international guidelines, 9–12 months of medical management is standard.[21] While the majority of tuberculomas resolve in 12–24 months, in patients with multiple or larger lesions prolonged treatment extending beyond two years may be required. In some patients, the release of inflammatory mediators during treatment can cause a paradoxical worsening of symptoms that is treated with anti-inflammatory medications in addition to the standard anti-tuberculosis regimen.[20]

Exceptionally large tuberculomas, those exerting a mass effect on the brain, and those which fail to respond to medical management required surgical excision. In some cases, surgical excision is necessary for diagnosis as well as treatment.[3] When intracranial pressure rises in the setting of tuberculoma, removal is considered a surgical emergency.[20]