A diagnostic challenge after neoadjuvant chemoimmunotherapy: looking beyond tumor recurrence

Introduction: Neoadjuvant and/or perioperative chemoimmunotherapy has changed the natural history of non-small cell lung cancer. However, immunotherapy is associated with a distinct toxicity profile and an increased risk of latent infection reactivation. Case report: A 67-year-old woman was diagnosed in December 2021 with stage IIIB lung adenocarcinoma (9th edition AJCC-TNM), with positive PD-L1 expression. She received neoadjuvant chemoimmunotherapy followed by surgery, achieving a complete pathological response. Concurrently, she received antituberculous therapy for latent tuberculosis. The first follow-up chest and abdominal CT scan revealed findings suggestive of pulmonary and cerebral recurrence, prompting further investigation. Histological analysis of the pulmonary lesion demonstrated acute and chronic inflammation with granulomatous and giant cell components. Clinically, the patient had received antibiotic therapy for productive cough without improvement. Given the diagnostic suspicion of active tuberculosis, antituberculous therapy was initiated. Upon completion of antituberculous treatment, the cerebral lesion had resolved and the pulmonary pseudonodular lesion remained stable with associated fibrotic tracts. The patient currently remains asymptomatic and in complete response. Discussion: Immunotherapy is associated with an increased risk of latent infection reactivation. Conclusions: Therefore, in the setting of new-onset pulmonary lesions, tuberculous infection should be considered as a diagnostic possibility.