Diagnostic Approach for TB Arteritis

Initial Clinical Evaluation

The American College of Radiology recommends proceeding immediately with CT or MRI angiography to visualize vessel wall thickening and stenosis, combined with chest CT to identify active pulmonary TB, in immunocompromised patients with prior TB history and suspected TB arteritis 1
Immunocompromised patients, particularly those with HIV (especially CD4 <200), those on anti-TNF medications, or receiving chronic corticosteroids, require heightened suspicion for atypical TB presentations 1, 2
Documenting TB exposure history, including endemic country residence, close TB contacts, and high-risk settings, is crucial in the initial clinical evaluation 1, 2
Screening for systemic TB symptoms, such as unexplained weight loss, night sweats, fever, prolonged cough, hemoptysis, and fatigue, is essential 1, 2

The American College of Radiology suggests that MRI is preferred when avoiding radiation exposure is desirable 1
CT chest is mandatory in immunocompromised patients, even with normal chest radiography, as chest X-rays are frequently deceptively normal in this population 1, 2
Looking for upper lobe fibro-cavitary disease, mediastinal/hilar lymphadenopathy, or atypical infiltrates on CT chest is important 1, 2, 3
Do not rely on chest radiography alone in immunocompromised hosts with low CD4 counts 1, 2

A tuberculin skin test (TST) ≥5mm induration is considered positive in immunocompromised patients, those with recent TB contact, or radiographic evidence of old TB 4, 5, 2
The Interferon-Gamma Release Assay (IGRA) is preferred in BCG-vaccinated individuals to avoid false-positive results 2
Negative TST/IGRA does not exclude active TB in immunocompromised patients due to anergy 4, 5

Never interpret a negative chest X-ray as excluding TB in immunocompromised patients—proceed directly to CT 1, 2
TST/IGRA only indicate TB infection, not active disease; positive results require imaging and microbiological workup to distinguish active from latent TB 2
Anergy testing is controversial and unreliable; low risk of TB exists even with negative PPD in anergic patients 4, 5

Definitive diagnosis of TB arteritis requires evidence of active or latent TB infection through positive TST/IGRA (≥5mm in immunocompromised) 4, 5, 2
In immunocompromised patients with prior TB history, maintaining an extremely high index of suspicion is crucial, as presentations are atypical with negative skin tests, diffuse infiltrates, and extrapulmonary involvement being common 1