Acute Leukemia and Latent Tuberculosis Infection in Italy: Quantiferon-Tb Test Screening in a Low Tuberculosis Incidence Country.

Background: Identification of latent tuberculosis infection (LTBI) is a critical step of tuberculosis surveillance, especially in low-incidence countries. However, it is limited to situations with a higher probability of developing active disease, e.g., patients with hematological malignancies. According to guidelines, in TB non-endemic countries, no clear screening program is established at diagnosis for patients with acute leukemia (AL). The primary endpoint of this study was to establish the prevalence of LTBI in patients with a diagnosis of AL using QuantiFERON (QFT)-TB. Secondarily, radiological and clinical features driving the increased risk of LTBI were evaluated.

Methods: QFT-TB screening was performed before induction or consolidation in all patients with AL (myeloid and lymphoid) treated at our Institution between October 2019 and August 2023.

Results: We accrued 62 patients, of whom 7 (11,3%) tested positive, without any symptoms or signs of active TB, and 2 (3,2%) resulted as indeterminate. All positive patients started prophylaxis with isoniazid 300 mg daily, while patients whose test was indeterminate did not receive any prophylaxis. Active TB was excluded by imaging, as well as microscopic, cultural, and molecular examination on bronchoalveolar lavage if signs of any infection were detected. During the 46 months of observation, no patients developed TB reactivation.

Conclusions: Despite the low sample size, 1/10 of our patients had prior TB exposure, hinting that LTBI could be more common than expected in Italy. This finding suggests implementing TB screening in the pre-treatment setting, particularly at a time when more active treatments are becoming available also for patients ineligible for intensive chemotherapy.