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Findings: Chest x-ray - Right upper lobe consolidation, Right hilar fullness which is suggestive of lymphadenopathy. Head CT with contrast - ring-enhancing lesion at 4th ventricle, ventriculomegaly, enhancement of basilar cisterns, c/w meningitis.

Diagnosis:Tuberculosis.

Discussion: The primary site of tuberculosis infection in children and adolescents is pulmonary (76%), followed by lymphatic (14%), pleural (3.3%), meningeal (2.4%) and miliary tuberculosis (1.2%) Primary infection usually starts as a small single subpleural focus. From this size, spread occurs through lymphatics to hilar and mediastinal lymph nodes. Then to regional nodes. The initial pulmonary inflammatory exudate produces localized air-space disease that can involve an entire segment or lobe. A pleural effusion may also be present. Lymph node enlargement can cause airway obstruction by extrinsic compression, either with resultant atelectasis or air-trapping. Clinically, the child is often not acutely ill.

Extrathoracic manifestations account for 20% of tuberculosis in children, where sites are seeded during lympho-hematogenous spread during the incubation period. Remote disease usually follows the primary infection by 3 months (miliary TB or meningitis), but can be delayed by up to 20 years (genitourinary disease).

Tuberculous meningitis causes more deaths than any other form of tuberculosis. It often does not have the typical symptoms of fever or headache. This meningitis probably results from the rupture of a tuberculoma. A gelatinous exudate fills the basal cisterns, which will enhance with contrast. Ventriculomegaly will be present in 50-77% of patients.

A tuberculoma is a ring-enhancing or punctate lesion which is often parenchymal (at the gray-white matter junction), but can be dural-based. When the tuberculoma is over 2 cm., it tends to have a thick enhancing ring with little or no surrounding edema. Solitary lesions are more frequent below the tentorium. In children, 60% of tuberculomas are in the posterior fossa, usually the cerebellum.

References:
1. Caffey's Pediatric X-ray Diagnosis - 9th Ed. Silverman, Kuhn. 1993.

2. Fundamentals of Diagnostic Radiology . Brant, Helms. 1994.

3. Pediatric Neuroimaging-2nd Ed. Barkovitch. 1995.

4. Practical Pediatric Imaging, 2nd Ed. Kirks. 1991.

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