An Unsuspecting Case Of Central Nervous System Tb

SESSION TITLE: Fellows Chest Infections Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: CNS TB is a rare, but well known, manifestation of extra-pulmonary tuberculosis. The most common presentation is meningitis (TBM), however encephalitis, intracranial tuberculomas, and brain abscesses may also be seen[1]. Here we present a case of tuberculous brain abscess (TBBA) formation at the site of a ventriculoperitoneal shunt (VPS). CASE PRESENTATION: A 69 year old Haitian male presented with altered mental status and stroke like symptoms. History remarkable for VPS placed 2 years prior for normal pressure hydrocephalus and head/neck cancer, with completion of radiation 9 months prior to presentation. Routine EEG revealed focal status epilepticus and anti-epileptics were started. Brain CT revealed enlarged ventricles and signs of abscess formation around the shunt in the right parietal lobe. CSF analysis from LP and VPS remarkable only for elevated protein initially. Surgical resection of ventriculostomy performed with identification of a thick capsule with purulent fluid just beneath the dura. Pathologic evaluation revealed brain abscess, with granulomatous inflammation and acid fast bacilli morphologically consistent with Mycobacterium tuberculosis. An external ventricular drain was placed and high dose corticosteroids initiated. Anti-tuberculous therapy was also started, with multiple adjustments made throughout course of therapy due to elevated serum transaminases and recurrent seizure activity, with plan to continue treatment for 1 year. DISCUSSION: CNS TB occurs in less than five percent of all patients with TB, with only a fraction presenting as tuberculous abscess[2]. Clinical suspicion for TB must be high when evaluating for TBBA, as Mycobacterium has been cited as the causative organism in less than 1 percent of brain abscesses[3]. In our case, TB was only suspected after identification of AFB on gram stain from purulent aspirate and VPS tip. While VPS obstruction has been described in TBM in the setting of elevated CSF protein, and abdominal pseudocyst formation is a known complication of VPS, to our knowledge, TBBA formation in this setting has never been described[4,5]. TBM, CNS tuberculoma and TBBA formation are believed to be the result of hematogenous spread, with TBBA appearing more similar to pyogenic abscesses than tuberculomas[2,6]. It has also been postulated that TB reactivation can occur at a site of inflammation due to local trauma, with onset of symptoms between 1-42 weeks after said insult[7]. The pathophysiology remains unclear regarding the abscess formation in our patient, however we postulate development of TBM with subsequent shunt obstruction and resultant abscess formation, perhaps triggered from inflammation secondary to previous head/neck radiation. CONCLUSIONS: Diagnosis of tuberculous abscess relies heavily on radiographic appearance and a high clinical suspicion, with confirmation obtained only after direct tissue examination. Reference #1: Rock RB, Olin M, Baker CA, Molitor TW, Peterson PK. Central nervous system tuberculosis: Pathogenesis and clinical aspects. Clin Microbiol Rev. 2008. doi:10.1128/CMR.00042-07 Reference #2: Schaller MA, Wicke F, Foerch C, Weidauer S. Central Nervous System Tuberculosis: Etiology, Clinical Manifestations and Neuroradiological Features. Clin Neuroradiol. 2019. doi:10.1007/s00062-018-0726-9 Reference #3: Brouwer MC, Coutinho JM, Van De Beek D. Clinical characteristics and outcome of brain abscess?: Systematic review and meta-analysis. Neurology. 2014. doi:10.1212/WNL.0000000000000172 DISCLOSURES: No relevant relationships by David Ashkin, source=Web Response No relevant relationships by Susanna Leonard, source=Web Response No relevant relationships by Megan Ninneman, source=Web Response No relevant relationships by Rene Rico, source=Web Response