Miliary meningeal tuberculosis - an unusual imaging presentation for an early definitive diagnosis

Purpose: Tuberculous meningitis (TBM) causes significant morbidity and mortality in young children. Early treatment can be initiated with magnetic resonance (MR) imaging diagnosis. We present MR-detectable miliary meningeal TB in two patients. CASE 1: A 9-year-old girl developed fevers, cough, lethargy, and seizures. Brain MRI demonstrated multiple, small, T2-dark, rim-enhancing lesions, associated with cranial nerve and leptomeningeal enhancement. CSF showed pleocytosis, low glucose, and high protein. Chest CT showed mediastinal lymphadenopathy, multiple small interstitial lung nodules, and a splenic hypo enhancing lesion. Serial bronchoalveolar lavage studies were Xpert MTB/RIF and acid-fast negative. Endobronchial US-guided biopsy of a subcarinal lymph node was positive for Xpert MTB PCR. She was started on a 4-drug treatment for TBM and dexamethasone. Contact tracing revealed a remote positive contact with pulmonary tuberculosis. CASE 2: A 17-year-old female with Crohn's disease on adalimumab developed refractory ear infections despite multiple courses of antibiotics. She underwent myringotomy, with negative aerobic ear fluid culture. Brain MRI, obtained due to persistent otorrhea, showed multiple, small, round, T2-dark lesions. CSF studies were normal. CT chest, abdomen, and pelvis to assess for disseminated disease showed left upper lobe tree-in-bud nodules, hypoattenuating splenic lesions and a left obturator internus abscess with adjacent osteomyelitis. She underwent CT-guided aspiration of the obturator muscle collection, bronchoscopy with bronchoalveolar lavage, biopsy of two preexisting chronic skin lesions, and ear fluid aspiration. QuantiFERON Gold was positive. Ear fluid was Xpert MTB/RIF assay and acid-fast stain positive. Cultures from the ear fluid, skin tissue, muscle tissue, and alveolar lavage showed growth of acid-fast bacilli. She was started on 4-drug therapy and prednisone.

Conclusion: Our cases highlight that TBM in many cases remains a diagnostic dilemma - both our patients presented in a prolonged atypical manner. The term miliary TB not only refers to a pattern of interstitial nodules on chest radiographs but also indicates the hematogenous spread of the disease and concurrent pulmonary and extrapulmonary involvement with high risk of TB meningitis. We promote the use of the term miliary meningeal TB - in both cases, the neuroimaging diagnosis of TB preceded both chest imaging and laboratory confirmation of the disease. Miliary meningeal nodules on MRI may have characteristic T2 low signal and may be more conspicuous in children and immunocompromised individuals where background basal meningeal enhancement is less prominent.